Simple Project Circuit

Wireless Telephone Line Spy Circuit

2011-05-19T03:06:00.000+07:00

Here’s a design of a phone bug circuit. This wireless telephone line spy circuit can be used to transmit the phone conversation to a nearby FM radio. This circuit must connected to a normal phone line. This is the figure of the circuit;

The first transistor is turned off, if the voltage drops to less than 15v (if the telephone line is in use). It will enable the second transistor to oscillate at approx 100MHz. Then transmit the phone conversation to a nearby FM radio.

Phone Incoming Call Flasher Circuit

2011-05-19T03:04:00.000+07:00

Here’s a design circuit of phone message flasher, an alternative way to get alarmed when there is an incoming call. This is the figure of the circuit;

When the phone rings, high line voltage will be detected by A differential amplifier with hysteresis (Q2, Q3, and Q1). This action will turn on multi vibrator Q5/Q6, Q4. The LED will flashed via Q7. When the phone line voltage drops to less then 9V, the Q2 and Q1 will be turned off, which indicates an off hook condition.

Low Cost Precision Light Control / Dimmer Circuit

2011-05-19T03:03:00.000+07:00

Using a the controlled-half-plus-fixed-half-wave phase control method, this circuit can regulate an 860 a watt lamp load from half to full power. This circuit control the light output of the lamp from 30% to 100% because Half power applied to an incandescent lamp gives 30% of full light output. This is the figure of the circuit;

Simple Positive (+) to Negative (-) Voltage Inverter Circuit

2011-02-21T10:50:00.000+07:00

This is a simple circuit that can be used to convert the positive input voltage become negative voltage. Here’s the figure of the circuit;

Component list:

Part    Total Qty.    Description
R1    1    24K 1/4 Watt Resistor
R2    1    56K 1/4 Watt Resistor
C1    1    3300pF 25V Ceramic Capacitor
C2    1    47uF 25V Electrolytic Capacitor
C3    1    10uF 25V Electrolytic Capacitor
D1, D2    2    1N4148 Silicon Diode
U1    1    555 Timer
MISC    1    Wire, Board

In this circuit, V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So, for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps. For better regulation, a 79LOxx series regulator can be used. A zener diode may also be used to regulate the output voltage.

Simple Galvanometer Circuit

2011-02-21T10:49:00.000+07:00

This circuit is design for galvanometer circuit. According to Wikipedia.org, a galvanometer is an analog electromechanical transducer to be used for detecting and measuring electric current (ammeter). In this circuit design, the voltage across Rm and Rv is the same because they are in parallel. The resistor Rv is a variable resistor. Here’s the figure of the circuit;

Simple of XTal Tester Circuit

2011-02-21T10:46:00.000+07:00

This is a design circuit for a simple XTal tester circuit. T1 and XTal have formed an oscillator. Here’s the figure of the circuit;

In this circuit, C1 and C2 are voltage divider for oscillator. If the XTal is safe, the oscillator will work well and its output voltage will be rectified by C3, C4, D1 and D2, then T2 will run and LED will light. The circuit is suitable to test 100KHz - 30MHz Xtal.

Simple Voltage Doubler Circuit

2011-01-27T21:19:00.000+07:00

This is a design circuit that is output a voltage Vout that is approximately twice the level of the Vcc voltage. The circuit uses a 555 timer IC configured as an astable multi vibrator, i.e., it generates a continuous square wave signal of a set frequency as long as its reset pin (pin 4) is held high. This means that the 555 output toggles between '1' and '0' continuously at the set frequency. This is the figure of the circuit;

When the circuit is powered up and the 555 output (pin 3) goes to logic '1' for the very first time, its near-Vcc voltage level causes C3 to charge up through D2 and also reach near-Vcc level. When the output goes to logic '0', C2 charges from Vcc through D1, also to a near-Vcc level. When the 555 output goes back to logic '1' again, C3 may still have some (if not most) of its charge left, and will allow to charge up to a higher level since it is now effectively in parallel with the series circuit of the 555 level '1' output and the charged C2.

After several cycles of C2 and C3 alternately charging, C3 will subsequently build up a voltage level equal to almost twice the Vcc level. This C3 voltage comes from the charge pumped in by the sum of the C2 voltage (near-Vcc) and the 555 output voltage when it is at logic '1' (also near-Vcc). At this point, the output Vout of the circuit will already be almost twice the Vcc level.

Simple Transistor Circuit Substitute for SCR

2011-01-27T21:17:00.000+07:00

A silicon-controlled rectifier (SCR) is a solid-state device that doesn't allow current to flow until it is triggered to conduct. The SCR is a four-layer device, i.e., its structure consists of four layers of alternating semiconductor material type: p-n-p-n. Once triggered, it will conduct current in only one direction. SCR's are generally used for AC switching. This is the figure of the circuit;

This circuit is equivalent to a silicon-controlled rectifier (SCR). It employs a PNP and an NPN bipolar transistor to mimic the p-n-p-n structure of an SCR. In this circuit, once NPN transistor Q2 is triggered by a positive input to its base, it starts pulling down the voltage at the base of PNP transistor Q1. This would drive Q1 to conduct, which will then supply Q2's base with continuous current to keep it 'on'.

Under this state, both transistors will conduct indefinitely, as long as there is available current flowing between the anode (A) and the cathode (K). The circuit will only turn 'off' if the supply of current from A to K is interrupted.

Simple Integrator Circuit

2011-01-27T21:13:00.000+07:00

This is a design circuit for simple integrator circuit. The potentiometer is connected to the "rails" of the power source through 100 kΩ resistors, one on each end. This is to limit the span of the potentiometer, so that full movement produces a fairly small range of input voltages for the op-amp to operate on. At one extreme of the potentiometer's motion, a voltage of about 0.5 volt (with respect the ground point in the middle of the series battery string) will be produced at the potentiometer wiper. This is the figure of the circuit;

At the other extreme of motion, a voltage of about -0.5 volt will be produced. When the potentiometer is positioned dead-center, the wiper voltage should measure zero volts. Connect a voltmeter between the op-amp's output terminal and the circuit ground point. Slowly move the potentiometer control while monitoring the output voltage. The output voltage should be changing at a rate established by the potentiometer's deviation from zero (center) position. To use calculus terms, we would say that the output voltage represents the integral (with respect to time) of the input voltage function. That is, the input voltage level establishes the output voltage rate of change over time. This is precisely the opposite of differentiation, where the derivative of a signal or function is its instantaneous rate of change.

If you have two voltmeters, you may readily see this relationship between input voltage and output voltage rate of change by measuring the wiper voltage (between the potentiometer wiper and ground) with one meter and the output voltage (between the op-amp output terminal and ground) with the other. Adjusting the potentiometer to give zero volts should result in the slowest output voltage rate-of-change. Conversely, the more voltage input to this circuit, the faster its output voltage will change, or "ramp."

Simple Proportional-Integral Motor Speed Control

2011-01-25T20:38:00.000+07:00

This is a design of frequency-to-voltage converter application similar with RPM/Speed Indication is motor speed control. Here the converter is used to measure the actual speed which will be fed back to keep the actual speed stabilized according to a reference. This is the figure of the circuit;

If the speed is to high, the output of the F/V converter will reduce the drive power delivered to the motor, and vice versa. The resistor across the output and the inverting input determine the proportional gain, and the capacitor determine the integral gain. This negative feedback mechanism is the core of this proportional motor speed control system. [System's block diagram source: Microchip Application Note]

Simple Transistor Tester Circuit Using 555 IC

2011-01-10T23:29:00.000+07:00

This is a circuit for testing whether a transistor is shorted or open usually done by ohm meter. You test if the base to emitter or collector permit a current flow in one direction. This is the figure of the circuit;

The 555 timer ( IC1 ) operate as a 12hz oscillator. The output of this oscillator (pin 3) drives the 4027 flip-flop (IC2). Clocked by the oscillator, this flip-flop give complementary voltage outputs on pin 15 and 14. The outputs drives LED1 and LED2 through the current limiting resistor R3. The LED’s are arranged so that if the polarity across the circuit is one way then only one LED will light and if the polarity reverses then the other LED will light, and when no transistor is connected to the tester then the LED’s will alternately flash. The IC2 outputs are also connected to resistors R4 and R5 with the junction of these two resistors connected to the base of the transistor being tested. If a good transistor connected to the tester, the transistor will turn on and produce a short across the LED pair. If a good NPN transistor is connected then only LED1 will flash. If a good PNP transistor is connected then only LED2 will flash. If the transistor is open both LED’s will flash and if the transistor is shorted then neither LED will flash. After receiving a feedback from our reader, I’ve checked the datasheet of 4027 JK flip-flop, and found that the pin 12 and 13 in the schematic diagram above should be interchanged.

Simple Remote Sensor System Pre-Amp

2011-01-10T23:26:00.000+07:00

This is a design circuit for remote sensor might cause a trouble if it’s a passive type, has very low power output, and should be connected with relatively long cables. By supplying a current or voltage source through its connection wire, it’s possible to make long enough wiring without suffering much noise/interference. The following schematic diagram show a circuit consist of LM10 to make a remote vibration sensor connection works fine. We don’t need a separate wires for signal and power supply, we send them on the same cable pair. This is the figure of the circuit;

[Circuit diagram source: National Semiconductor Application Notes]

Simple Humidity Sensor Circuit

2011-01-10T23:24:00.000+07:00

This is a humidity sensor to give an alert of boat leakage, or when your books start being flooded by heavy rain attack on your broken roof, or anything you can imagine. A simple humidity sensor (a humidity probe) can be constructed using two copper wires placed as close as possible to each other, but no touching. This simple circuit can be used to make your simple humidity detector. This is the figure of the circuit;

If the humidity increase, the probe resistance will drop and the Schmidt trigger formed by Q1 and Q2 will be triggered, and the Q2 collector become low, this condition will trigger the S-R (set-reset) flip-flop formed by U1A, U1B. After triggered, the relay will remain active until you reset the circuit by pressing the SW1 switch.

Simple 3A Switching Regulator Circuit

2010-12-24T07:23:00.000+07:00

This is a design circuit for a simple and low cost switching regulator using the IC LM317 that can deliver up to 3A of current. The input voltage range of this circuit is between 8 to 35V DC and the output voltage can be adjusted between 1.8 to 32V DC. The output voltage can be adjusted by using the POT R4. This is the figure of the circuit;

When compared to linear voltage regulators the switching voltage regulators are much power efficient. In the case of linear voltage regulators the difference between the input and output voltage is just wasted and for switching regulators there is almost no such wastage and that’s why the switching regulators have great power efficiency ranging up to 85% . In simple words, the switching regulator operates by taking small bits of energy from the input voltage source and then transferring it to the output with the help of a solid state switch and a control circuitry. Since the switching element is either fully open or closed at any moment, no energy is wasted across it. The control circuit controls the duty cycle of the solid state switch which in turn determines rate at which energy is transferred to the output.

Simple 3 Band Tone Control Circuit

2010-12-24T07:17:00.000+07:00

This is a design circuit for the simple design of a 3 Band Tone Control Circuit Diagram. This is the figure of the circuit;

R1 is left up to the user depending on gain needs. This circuit design was originally intended for home audio use, but should be able to hacked into an effect circuit with very minor modification.

Simple Basic Symmetric Power Supply Circuit

2010-12-07T06:10:00.000+07:00

This is a design circuit for the basic for standard symmetrical power supply. If your circuit need high current then this circuit is suitable. This is the figure of the circuit;

You need a center-tapped transformer to build this symmetric power supply. This power supply circuit is widely used in op-amp application, as well as in high-rated power amplifier.

Simple Shunt Voltage Stabilizer Circuits

2010-09-29T18:43:00.000+07:00

This is a circuit for a simple voltage stabilizer circuit that employs a zener diode and a single resistor. In this circuit, the zener diode, which is the stabilizing component, is in parallel (or in shunt) with the load, which is why it is also called a shunt stabilizing circuit. This is the figure of the circuit;

The value of R must be chosen so that a 'holding current' of 2 mA will flow into the zener diode even at the lowest input voltage and maximum load current. The zener diode maintains the output voltage level by 'conducting' the excess current to ground whenever the voltage across it becomes excessive.

Simple Series Voltage Stabilizer Circuits

2010-09-29T18:32:00.000+07:00

This is a circuit for simple voltage stabilizer circuit that employs a resistor, a zener diode, and an NPN transistor. In this circuit, the zener diode is used to stabilize the base voltage of the NPN transistor, which carries the load current. This is the figure of the circuit;

The load transistor is in series with the load, which is why this circuit is also known as a series stabilizer. Unlike the amplified zener shunt stabilizer, the dissipation of the transistor increases only when the actual load current increases, making its operation more efficient.

Simple OP90 Single Op Amp Full-Wave Rectifier

2010-09-29T18:22:00.000+07:00

This is a design circuit for a full-wave rectifier circuit that provides the absolute value of input signals up to ±2.5 V even though operated from a single 5 V supply. This is the figure of the circuit;

The amplifier acts as a unity-gain inverter for negative inputs. The op amp output is forced by positive signal to ground. The 1N914 diode becomes reversed-biased and the signal passes through R1 and R2 to the output. Load impedance cause an asymmetric output since output impedance is dependent on input polarity. This can be corrected by reducing R2 for constant load impedance. A second OP90 can buffer varying or heavy loads. The output of the full-wave rectifier with a 4 Vp-p, 10 Hz input signal also shown in figure below. [Circuit's schematic diagram source: analog.com]

Simple Negative Feedback Series Voltage Stabilizer Circuit

2010-09-29T18:10:00.001+07:00

This is a design circuit for more complex series voltage stabilizer circuit, utilizing an operational amplifier (IC1) to 'slow down' or turn off the load transistor Q1 when the output voltage is excessive. This is the figure of the circuit;

The zener diode ZD1 in this circuit is just used as a reference voltage for defining the threshold at which the op amp will turn Q2 and Q1 on or off. Because of this negative feedback mechanism, power is consumed more efficiently, since the load is only supplied with current when it needs it.

Simple Light Activated Buzzer Circuit

2010-09-29T18:02:00.000+07:00

This is a circuit for a simple buzzer circuit that is activated by light, i.e., the buzzer is on when there's ample light and off when it is dark. A general-purpose operational amplifier, the 741, is used as a comparator that determines whether there's enough light to turn on a self-oscillating piezoelectric buzzer. Its non-inverting input is connected to a photo resistor, a component whose resistance decreases as more light shines on it. Its inverting input, on the other hand, is connected to an almost fixed voltage, i.e., a proportion of the supply voltage as set by trimmer resistor R2. This is the figure of the circuit;

If there isn't enough light shining on the photo resistor, the buzzer is quiet. As more light shines on the photo resistor, its resistance decreases and causes the voltage across R1 to increase. At a certain level of lighting, the voltage across R1, which is also the voltage at the non-inverting input of the 741, becomes larger than the voltage at the inverting input. At this point, the 741 is triggered to output a 'high' level, turning on Q1. Q1 then activates the self-oscillating piezoelectric buzzer.

Simple DC Voltage Ripple Remover Circuit

2010-09-29T17:54:00.000+07:00

This is a circuit for a simple circuit for removing an AC ripple from a DC voltage. The main component of the circuit is an operational amplifier configured as a simple amplifier in common-mode operation. This means that both the inverting and non-inverting inputs of the op-amp get the same input voltage, i.e., a DC voltage Vin with an AC ripple Vripple. The only difference is that the inverting input has an input capacitor that blocks the DC voltage. This is the figure of the circuit;

Since the op-amp amplifies just the difference between the voltages at its two inputs, it cancels out the AC ripple (which appears at both inputs). On the other hand, the op-amp amplifies the DC voltage Vin since this is only present at the non-inverting input. However, the op-amp is configured to have a DC voltage gain equal to 1, so the output of this circuit is just equal to Vin. Since the AC ripple can only be cancelled cleanly if both op-amp inputs have equal gains, the 10K potentiometer is used to compensate for any inherent differences between the inputs' gains.

Simple DC Motor PWM Speed Control Circuit

2010-08-26T20:04:00.000+07:00

This is a circuit for DC motor circuit. This circuit is used PWM speed control using 555 timer IC. This is the figure of the circuit;

The 555 Ic is wired as an astable and the frequency is constant and independent of the duty cycle, as the total resistance (R charge + R discharge, notice the diode) is constant and equal to 22Kohm (givin a frequency of about 1Khz, notice the hum). When the potentiometer is all up, the Rcharge resistance is 1,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 21 Kohm, giving a 5% on duty cycle and a 1Khz frequency.

When the potentiomenter is all down, the Rcharge resistance is 21,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 1 Kohm, giving a 95% on duty cycle and a 1Khz frequency. When the potentiometer is at 50% , the Rcharge resistance is 11,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 11 Kohm, giving a 50% on duty cycle and a 1Khz frequency. The 555 provide good current capability to drive the mosfet fast and to drive a bipolar transistor.

Simple DC Motor PWM Speed Control Circuit

2010-08-17T19:51:00.000+07:00

This is a circuit for DC motor circuit. This circuit is used PWM speed control using 555 timer IC. This is the figure of the circuit;

When the potentiometer is all up, the Rcharge resistance is 1,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 21 Kohm, giving a 5% on duty cycle and a 1Khz frequency.

When the potentiomenter is all down, the Rcharge resistance is 21,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 1 Kohm, giving a 95% on duty cycle and a 1Khz frequency. When the potentiometer is at 50% , the Rcharge resistance is 11,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 11 Kohm, giving a 50% on duty cycle and a 1Khz frequency. The 555 provide good current capability to drive the mosfet fast and to drive a bipolar transistor.

Simple Microphone Amplifier Circuit

2010-07-13T06:53:00.002+07:00

This is a circuit diagram of a device which can hear faint sounds and those sounds which any normal microphone can not hear. This is a very useful circuit and one can use this circuit for many tasks this circuit can be used as a hearing aid. Use direct coupling and do not use bulky coupling or bypass capacitors. The circuit using only a few components the size of the circuit is very small so one can easily fit it in a small box. This is the figure of the circuit;

Capacitor 1 bypasses ac negative feedback due to which the gain is not affected. Q1, Q2 and Q3 are bc 337. Resistor 1 is used for volume control. Transistor 1, transistor 2 and transistor 3 all are direct coupled amps. Their operation is stabilized by direct current (DC) negative feed back through resistor 4.

Simple Loud Hailer Circuit

2010-07-13T06:52:00.002+07:00

This is a simple and useful circuit project of loud hailer the circuit uses only one transistor connected with transformer which puts out a loud sound. The circuit can be easily fixed in a metal package with the speaker mounted on the top. Heat sink is essential for the transistor or it will burn out, fix the circuit in metal package and also use this metal package as heat sink of transistor. This is the figure of the circuit;

Use carbon mic or telephone mic/telephone transmitter element. The circuit can be build inside of a speaker trumpet like the loudhailers available in market. Make sure that the mic is isolated from the speaker to prevent feedback. Use the transformer which will able to provide 5 watt output power.

Simple Lie Detector Circuit

2010-07-13T06:51:00.002+07:00

If you want to know someone is lying or not we can use lie detector. This is a simple lie detector that can be made in minutes. It works to detect someone who telling lie but it is not as sophisticated as the ones the professionals use. This is the figure of the circuit;

The skin resistance will go down when someone telling lie and this circuit works by measuring it. We can use electrode pads, alligator clips, or just wires and tape as the electrodes. We have to adjust R2 to position the meter at the center at the beginning of the interrogation (relax condition), then we can know someone is lying when the meter changes in response to a question.

[Schematic circuit source: aaroncake.net]

Simple Analog Multiplier Circuit

2010-05-18T20:02:00.000+07:00

This is a circuit for a simple embodiment of the analog multiplier. This circuit provides three quadrant analog multiplication which is relatively temperature insensitive and which is not subject to the bias current errors which is plague most multipliers and circumvents many of the problems associated with the log-antilog circuit. This is the figure of the circuit;

By considering A2 as a controlled gain amplifier, amplifying V2, whose gain is dependent on the ratio of the resistance of PC2 to R5 and by considering A1 as a control amplifier which establishes the resistance of PC2 as function of V1, circuit operation may be used. It is seen that Vout is a function of both V1 and V2 in that way. Drive for the lamp L1 is provided by the control amplifier(A1). L1 is driven by A1 until the current to the summing junction from the negative supply through PC1 is equal to the current to the summing junction from V1 through R1 when an input voltage (V1) is present. This forces the resistance of PC1 to a value proportional to R1 and the ratio of V1 to V- since the negative supply voltage is fixed. L1 also illuminates PC2 and causes PC2 to have a resistance equal to PC1 if the photoconductors are matched. The controlled amplifier (A2) behaves as an inverting amplifier whose gain is equal to the ratio of the resistance of PC2 to R5. Vout becomes simply the product of V1 and V2 if R5 is chosen equal to the product of R1 and V-. To provide any required output scale factor, R5 may be scaled in powers of ten.

Since the T.C. of resistance is related to resistance match for cells of the same geometry, PC1 and PC2 should be matched for best tracking over temperature. Varying the value of R5 as a scale factor adjustment is used to compensate small mismatches. The photoconductive cells should receive equal illumination from L1, a convenient method is to mount the lamp midway between them. Controlled spacing and a thermal bridge between the two cells to reduce differences in cell temperature is provided by this mounting method. To the use of FET’s or other devices to meet special resistance or environment requirements, we can extend this technique.

An inverting output whose magnitude is equal to one-tenth the product of the two analog inputs is given on this circuit. Positive value is restricted for input V1 but V2 may assume both positive and negative value. By the lamp time constant, his circuit is restricted to low frequency operation. To minimize errors due to input offset current as outlined in the section describing the photocell amplifier, R2 and R4 are chosen. To reduce in-rush current when firdt turning on the lamp (L1), R3 is included.

[Circuit source: National Semiconductor Notes]

Simple Step-up PWM DC-DC Converter Integrated with 4 Buffers

2010-04-15T16:40:00.002+07:00

This is a circuit for converter that is a simple form for DC to DC Converter circuit. This circuit is based on LM2711 from National Semiconductor. This is the figure of the circuit;

The LM2711 has a current mode PWM step-up DC/DC converter with a 1.4A, 0.17 internal switch. Capable of generating 8V at 300mA from a Lithium Ion battery, the LM2711 is ideal for generating bias voltages for large screen LCD panels. The LM2711 can be operated at switching frequencies of 600 KHz or 1.25MHz, allowing for easy filtering and low noise. An external compensation pin gives the user flexibility in setting frequency compensation, which makes possible the use of small, low ESR ceramic capacitors at the output. The LM2711 uses a patented internal circuitry to limit startup inrush current of the boost switching regulator without the use of an external soft start capacitor. An external soft start pin enables the user to tailor the soft start to a specific application. The LM2711 contains 4 Gamma buffers capable of supplying 50mA source and sink. The TSSOP-20 package ensures a low profile overall solution. [Schematic circuit source: National Semiconductor Notes]

Simple Precision Power Regulator Circuit

2010-04-15T16:39:00.000+07:00

Making a precision voltage source is easy, but not so easy if the voltage should be consistent over wide range of ambient temperature. Such requirement might be needed in high precision measurement system, for providing reference voltage in analog to digital conversion for example. This is a design circuit for precision power regulator. This is the figure of the circuit;

This circuit is based on LM 336. LM336 voltage references are easier to use than zener diodes. Their low impedance and wide current range facilitate biasing in any circuits. Besides, the breakdown voltage or the temperature coefficient can be adjusted so as to optimize the performance of the circuit. [Circuit diagram source: STMicroelectronics Application Note]

Simple Power Battery Tester Circuit

2010-03-31T05:02:00.000+07:00

This is a simple design circuit for battery tester circuit. In this circuit, operating will controlled by transistor 2N3904. This is the figure of the circuit;

In the circuit, LED will turn on if the voltages is over 42V. Threshold will increase about 1 V per 1 kilo ohm increase in R2. The current drain is about 7 mA with button pressed.

[Circuit schematic source: Hobby Projects Application Notes]

Simple pH-Electrode Circuit

2010-03-31T04:58:00.000+07:00

A pH electrode measures hydrogen ion (H+) activity and produces an electrical potential or voltage. The operation of the pH electrode is based on the principle that an electric potential develops when two liquids of different pH come into contact at opposite sides of a thin glass membrane. This is a design circuit for the measurement. This is the figure of the circuit.

Amplifier U1 off sets the pH electrode by 512 mV. This is achieved by using National's LM4140A-1.0 precision micro power low-dropout voltage reference that produces an accurate 1.024V. That voltage is divided in half to equal 512 mV by the 10 kΩ resistor divider. The output of amplifier U1, which is set up in a unity-gain configuration, biases the reference electrode of the pH electrode with the same voltage, 512 mV, at low impedance. The pH-measuring electrode will produce a voltage which rides on top of this 512 mV bias voltage. In effect, the circuit shifts the bipolar pH-electrode signal to a uni-polar signal for use in a single-supply system. The second amplifier U2 is set up in a unity-gain configuration and buffers the output of the pH electrode. Again, a high-input impedance buffer between the pH electrode and the measurement instrument allows the circuit to interface with a greater variety of measurement instruments including those with lower input impedance. In most applications, the output voltage of the pH electrode is high enough to use without additional amplification. If amplification is required, this circuit can easily be modified by adding gain resistors to U2.

[Circuit Source: National Semiconductor Notes]

Simple Emitter Follower Driver with Speed-Up Capacitor

2010-03-31T04:55:00.000+07:00

This is a design circuit for follower driver circuit. This circuit is give illustrated an alternate method to reverse bias the MOSFET during turn-off by inserting a capacitor in series with the pulse transformer. The capacitor also ensures that the pulse transformer will not saturate due to DC bias. This is the figure of the circuit;

This is s simplest form design circuit. The Opto-isolators may also be used to drive power MOSFETs but their long switching times make them suitable only for low frequency applications. [Circuit source: National Semiconductor Notes].

Simple Programmable Current Source/Regulator Circuit

2010-03-24T13:26:00.000+07:00

This is a simple circuit of programmable current source/regulator. This circuit is used to generate current. This is the figure of the circuit;

This circuit uses L 200 as main component. The error amplifier of this circuit is disabled by shorting pin 4 to ground. The value R is used to fix the output Io :

Io=(V5-2)/R
The output voltage can reach a maximum value Vi
– Vdrop=Vi 2 V (Vdrop depends on Io ).

[Source: SGS-Thomson Microelectronics Application Note]

Simple Stable Low Frequency Crystal Oscillator Circuit

2010-03-13T08:46:00.002+07:00

This is the design circuit for a Colpitts-crystal oscillator circuit. It is suitable for low frequency crystal oscillator circuits. Using the 2N3823 JFET, this circuit has excellent stability because the temperature will not vary the 2N3823 JFET circuit loading. This is the figure of the circuit.

This is a simple form circuit for the oscillator. [Circuit Schematic Source: National Semiconductor Application Note]

Simple Current Monitor Circuit

2010-03-13T08:45:00.002+07:00

This is a simple design circuit for monitoring and detecting the current flow. This circuit is based on LM301A and FET. This is the figure of the circuit;

On the circuit diagram, R1 is used to senses current flow of a power supply. We could use JFET as a buffer because Id=Is, therefore the power supply current flow is accurately reflected by the output monitor.

Simple 4 Channel Commutator Circuit

2010-03-13T08:44:00.002+07:00

This is design circuit for commutator circuit. This circuit is simplest form. The circuit is built by four FET that can be use for 4 channels. This is the figure of the circuit;

To reach low channel ON resistance (<30 Ohm) and low OFF current leakage, 4-channel commutator uses the 2N4091. The DM7800 voltage translator is a monolithic device. This devices give us +10V to -20V gate drive to the JFETs while at the same time giving DTL-TTL logic compatibility.

Simple Voltage Comparator Using CA3140

2010-02-18T12:31:00.000+07:00

This is a design circuit for simple comparator circuit. This circuit is indicates when the input voltage differs from two defined limits, V1 and V2. The limits that can be adjusted and the circuit is designed to trigger the adjustable “window”. Supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. This circuit is work based on CA3140 single chip IC. This is the figure of the circuit.

One application here is to monitor a 12V car battery. V1 can be set to 14V and V2 to 11V thus giving an indication of more than the cost or weak batteries. Op-amp used here is the CA3140 MOSFET. They are used to advantage because they have less output offset voltage and can switch to 0volts close. If any other is use op-amps like the LF351 or CA741 will need to have an offset null control. This is just a 10k preset reached between pins 1 and 5, the wiper connected to the negative supply op-amps or 4 pins. With this circuit the op-amp will turn on the LED if the input voltage out of limits, the two 1N4148 diodes to form an “AND”-gate at the output. Input voltage to be monitored are fed through a series of 10k resistor on the input of both op-amps. If the input voltage is greater than the limit set by V1 it will CA3140 output swing to almost full supply voltage and LED lights. Similarly, if the input voltage is less than the limit set by V2 the op-amp will swing to the Vcc and the LED light.

Simple Monitoring Status of Roof Equipment Circuit Using LM324

2010-02-18T12:28:00.000+07:00

This is a design circuit that can be used for monitoring the status of roof equipment. This circuit is work with based on LM324 for controller the circuit. This is the figure of the circuit.

The circuit works as follows: with the switch open (e.g., TV antenna parked) input pin 2 is high so output pin 1 is low compared to the mid voltage at input pin 3. So input pin 6 is low and thus output pin 7 is high and the green LED lights. When the switch is closed (the antenna is up) input pin 2 is low so output pin 1 is high, input pin 6 is high and output pin 7 is low and the red LED lights. Power consumption is ~18.3 mA green, 19.0 mA red. Only one circuit includes the divider string of resistors. All others use that mid voltage reference. And the circuit for the roof vents has the LED reversed since the switch is closed when the vents are closed. The fourth circuit and LED are unused so far.

Monitoring House Battery Current Circuit II

2010-02-18T12:25:00.000+07:00

This is a design circuit that has same with design in the last version. This circuit is an alternative when it is powered from the same battery as it monitors for current, this kind of meter requires a dual power supply with common-mode input voltage well between the supply voltages. This is the figure of the circuit.

The negative supply is easily provided, using a 7905 to provide -5V relative to voltage (1), the Load. A positive supply relative to voltage (1), the Load, requires addition of a voltage pump. One was made based on an NE555 IC running as an astable, the output of which was rectified to pump up a capacitor to a positive voltage. While this worked, there was a non-zero reading when the inputs were shorted: this could not be resolved for quite a while. It turns out that I had made a fundamental error of precision metering, namely the meter was drawing current from one of the sensor wires and the impedance of that wire is sufficient to cause a voltage drop of a couple of milli volts - the observed offset.

Monitoring House Battery Current Circuit I

2010-02-18T12:19:00.000+07:00

This is a one design circuit instrument to monitor current of battery. This circuit gives a check on operation of the motor home electrics. This is a simple form for design the instrument. This is the figure of the circuit.

This circuit is using Dick Smith Electronics DSE Q2220 3½ Digit LCD Voltmeter Module that is a 200 mV fsd voltmeter. So it will give a direct reading of Amps when connected across the EBL 269 shunt. Four-color ribbon cable to the LT400 Control and Switch Panel is soldered there to points near the main plug connector. There are pads for the current shunt on the circuit board (Pin 1 (yellow) and Pin 4 (orange) near the connector). Since analog voltages for the House Battery (Pin 4) (orange) and Starter Battery (Pin 8) (green) with Common negative at Pin 2 )(blue) are available there too, these are made accessible as touch points on the meter box front for reading with a multi meter. Installed in a wooden box, a photo of the meter is shown with it reading 1.8A consumption (negative current) due to two 10W halogen lights (1.7A) and the LT400 itself (~0.1A). The battery voltage touch points and ammeter power switch are on the left of the meter module. The meter box is attached to the wall by two keyholes in the back, and sliding to the left over countersink-head wood screws.

The Simple 5 Minutes Timer Relay Circuit Using CD4093B Single Chip IC

2010-02-11T18:53:00.000+07:00

This is a design circuit for timer relay circuit. This delay timer is a model design for the simple circuit. It is the nature of delays, all electrical devices. In this circuit has period in every 5 minutes. This is the figure of the circuit.

This circuit uses digital IC CD4093 is so simply too many. And the circuit is using relay driver transistors. It leads to a change in the situation with electricity or the electric charge of the equipment is. The calculation of the timer can calculate using this formula.

Timing = &nbsp ; 0.7 C1 x R1

Note: &nbsp ; &nbsp ; that R1 has a value of 1M with S1 switch start &nbsp ; at position “2″ .This equates to just short of 300 seconds for each position of S1. C1 and R1 through R2 may be changed for different timing periods. The output current from Pin 3 of the timer, is amplified by Q1 &nbsp ; (N3904) &nbsp ; and used to drive a relay.

Simple Ultra High Input Impedance Circuit For AC Unity Gain Amplifier

2010-02-11T18:51:00.000+07:00

This is an ultra high input impedance AC unity gain amplifier circuit. This circuit is used to get unity gain from ultra high input impedance AC. This is the figure of the circuit.

Because we can’t reduce input capacitance of this circuit, so we use the 2N4416 which has low capacitance. It is operated as a source follower with bootstrapped gate bias resistor and resistor . [Source: National Semiconductor Application Note]

Simple Indicates Differs Input Voltage Circuit Using CA3140

2010-02-11T18:48:00.000+07:00

This circuit is use for indicates when the input voltage differs from two defined limits, V1 and V2. The limits that can be adjusted and the circuit is designed to trigger the adjustable “window”. Supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. One application here is to monitor a 12V car battery. V1 can be set to 14V and V2 to 11V thus giving an indication of more than the cost or weak batteries. Op-amp used here is the CA3140 MOSFET. They are used to advantage because they have less output offset voltage and can switch to 0volts close. If any other use op-amps is like the LF351 or CA741 will need to have an offset null control. This is just a 10k preset reached between pins 1 and 5, the wiper connected to the negative supply op-amps or 4 pins. This is the figure of the circuit.

With this circuit the op-amp will turn on the LED if the input voltage out of limits, the two 1N4148 diodes to form an “AND”-gate at the output. Input voltage is to be monitored are fed through a series of 10k resistors on the input of both op-amps. If the input voltage is greater than the limit set by V1 it will CA3140 output swing to almost full supply voltage and LED light. Similarly, if the input voltage is less than the limit set by V2 the op-amp will swing to the Vcc and the LED light.

Simple LED Photo Sensor Circuit

2010-01-24T22:30:00.002+07:00

This is a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED. This is a simple design circuit. This circuit is based on FET. This is the figure of the circuit.

The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20. This produces a change of about 5 volts at the output from darkness to bright light. The 100K potentiometer can be set so that the output is around 7 volts in darkness and falls to about 2 volts in bright light.

Simple Brightness Controller Lamp Circuit

2010-01-24T22:29:00.002+07:00

This is a design for control the brightness lamp. The circuit can be used to control the brightness of low power incandescent lamps. This circuit is a simple design. The circuit is based on IC NE555. This is the figure of the circuit.

The IC is wired as an astable multi vibrator with variable duty cycle. The output of IC is connected to the base of transistor Q1.The Q1 drives the lamp. The duty cycle of the multi vibrator can be varied by varying the POT R4.As a result, the brightness of the lamp varies according to the position of the POT R4.The same circuit can be also used for speed control of small DC motors. The IC1 must be mounted on a holder. The lamp L1 can be a 6V / 200 mA lamp. The switch S1 can be SPST ON/OFF switch.

Simple 4-Transistor H-Bridge

2010-01-24T22:27:00.000+07:00

This is a simple design circuit for transistor bridge. This circuit is used 4 transistor for built the circuit. This is the figure of the circuit.

2N2905 and 2N2219 transistors are no longer being produced; I use 2N2907 and 2N2222 transistors in this circuit, with good results. You absolutely must use one bias resistor per transistor; I attempted to simplify the circuit by connecting the respective transistors' bases (so each pair of transistors could "share" a resistor) -- this made for a circuit that was simpler, much easier to freeform, and completely non-functional. This efficiency of this design is driven by 2 things -- the efficiency of the motor it's driving, and the size of the bias resistors. Just to make life interesting, these things are interrelated (more on this later).

Simple VHF Video Transmitter Circuit for Camera

2010-01-06T07:06:00.000+07:00

This is a simple design circuit for transmitter video. This circuit can radiate as far as 50m. This video transmitter can be used with the camera as a source. You can view them on VHF channel analog TV. Supply voltage to the transmitter can use 9V battery. This is the figure of the circuit.

Transistor components that are used for a video transmitter is BC548 or you can use another type of transistor BF199. Meanwhile, other passive components used SMD type. For winding coil L1 is 5 Turns 8 mm in diameter and use wire AWG 0.3-0.5 mm. Once you up the circuit this video transmitter, antenna use as a cable along the 50 cm. To determine the frequency of work, turn the trimmer capacitor 22 pf accordance with the frequency that you want.

Simple Headlight Flasher Circuit

2009-12-25T07:15:00.000+07:00

This is a design for flasher. This is a simple design. This circuit is based on 555 timer IC. This is the figure of the circuit.

It is used in the astable mode. The 555 timer output will go high for an adjustable period of time and then turn off. It will then repeat the procedure. The time is adjusted by R1. To hook up the circuit to your car you must locate the positive wire from the fuse box to the headlights. Cut the wire and insert the relay contact and bypass switch. The bypass switch will allow you to bypass the relay contact for normal headlight operation. In the alternating headlight configuration you must cut the positive wire to each headlight and wire in the relay contact.

Simple DC Motor Control Circuit

2009-12-25T07:12:00.000+07:00

This is circuit for control the DC motor. This circuit is control and work with based on transistor. This is a simple circuit. Here’s the figure of the circuit.

The S1 and S2 are normally open, push to close, press button switches. The diodes can be red or green and are there only to indicate direction. You may need to alter the TIP31 transistors depending on the motor being used. Remember, running under load draws more current. This circuit was built to operate a small motor used for opening and closing a pair of curtains. As an advantage over automatic closing and opening systems, you have control of how much, or how little light to let into a room. The four diodes surrounding the motor, are back EMF diodes. They are chosen to suit the motor. For a 12V motor drawing 1amp under load, I use 1N4001 diodes.

Simple Telephone Transmitter

2009-12-13T00:43:00.000+07:00

This is a simple design circuit for transmitter. This circuit is very useful for transmit telephone conversations. This circuit is work using based on transistor. Here’s the simple project circuit.

When the telephone receiver is on - hook to the line voltage of about 48 volts. R7 preset is adjusted to 24.7 V between the cathode of D2 and ground. In voltage Zener diode D2 will be in the breakdown and the transistor T1 will conduct. This makes the transistor T2 is OFF. When the receiver is off - hook, the line voltage drops to about 11 volts. This makes the transistor T1 is OFF and then T2 is ON. The T2 is switched ON condition will give way to the DC transistor T3 which is used in the FM transmitter. Transistor T3 is the cable as a common emitter radio frequency oscillator. In simple words the transistor T2 functions as ON / OFF switch for this oscillator. Modulated signal will be available to collectors of transistors T3 and id fed to the antenna signal through a capacitor C5. To L2 makes 3 changes of 21 SWG enameled copper wire on a plastic 12 mm. For the antenna, use a 1 meter insulated copper wire. Capacitor C3 can be 50pF trimmer.

Simple SW Receiver Using ZN414

2009-12-13T00:41:00.000+07:00

This is a design simple circuit of a SW receiver using the ZN414. This radio is the maximum operating frequency of about 4 MHz. The SW transmission is so strong that this receiver will work well with signals up to about 6 or 7 MHz. Here’s the simple project circuit of the SW receiver circuit.

The 10k resistor to control voltage for IC operation is very important for good performance. The tuned circuit consists of a variable capacitor and fixed air spaced coil. For the coil, I wound between 10 and 20 changed from a wire in an empty tube of about 1.5 inches in diameter. Branch, a distance so that the overall length is about 3 inches. Variable capacitor tuned 0-300 pF but there is plenty of room to experiment here. One final point, you will need an external antenna to receive broadcasts. I have a cable out of about 7 meters long and is quite effective. The antenna can be connected at both ends of the coil or through a series capacitor values of 10pF and 100pF.

Simple Audio Peak Level Meter Circuit

2009-12-13T00:40:00.000+07:00

This is a design for simple measurement that can be use for show the peak audio response on an analogue meter, similar to the tape recorder meters. This circuit is work with based on CA3140 op-amp as a non inverting amplifier, but with one addition a diode in the feedback loop. This is the figure of the circuit.

The circuit has a fast response time and slow decay time to indicate peak readings. The 1N4148 diode provides half wave rectification of the input signal, output dc smoothed by the 22u capacitor. The capacitor will charge the peak value of the input waveform, and then the liquid through the meter and the 18k resistor. I use the meter with FSD of 150uA, but each meter with FSD in the range of 50-250uA can be used. Disposal of time is about a quarter of a second. Increasing the cap to 22uF discharges a longer time.

Simple Differential Input Adapter Circuit

2009-12-08T12:12:00.000+07:00

This circuit is design for a differential input voltage that is required for measurement. This circuit is built using CA3140 op amp IC. Using only one operational amplifier, you can build an adapter to give your input for floating-ground reference voltage. This circuit is a simplest form. Here’s the figure of the differential input adapter circuit.

Use 1% tolerance metal film resistor for R1 and R2. Adjust VR1 to give zero output voltage when the input is shorted probe. You can use the supply voltage + UB-UB and between 3 to 20V, this is a symmetrical supply.

Simple Rain Detector Circuit

2009-12-07T03:58:00.000+07:00

This is a circuit for sensing the water with made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system. This is the figure of the circuit.

This circuit is using loud buzzer. This is a simple design circuit.
Part:
R1 - 1K 1/4 W Resistor
R2   - 680 Ohm 1/4 W Resistor
D1 - 1N4001 Silicon Diode
BZ1   - 12V Buzzer
S1   - SPST Switch
SCR   - 1C106B1 SCR

Simple Switcher 0, 5A Step-Down Voltage Regulator

2009-12-05T01:29:00.000+07:00

This is a simple design circuit for voltage regulator. This circuit is based on LM2574 single chip IC. This is the figure of the circuit.

The LM2574 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 0.5A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an adjustable output version. Other features include a guaranteed ±4% tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External shutdown is included, featuring 50 μA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under fault conditions.

Simple Single Transistor Relay Circuit

2009-12-05T01:27:00.000+07:00

This is a circuit relay that is requires a double pole, double throw relay in conjunction with a single transistor to allow toggling the relay with a momentary push button. This is a simple design circuit. This is the figure of the circuit.

The relay contacts are arranged so the 1000 uF capacitor will charge to about 2.7 volts, in the deactivated state. When the switch is closed, the capacitor voltage is applied to the transistor base through a 560 resistor causing the transistor to turn on and activate the relay. In the activated state, the relay contacts are arranged so the 3.3K resistor and 560 ohm resistor provide continues current to the transistor base maintaining the activated state. While in the activated state, the capacitor is allowed to discharge to zero through the 1K resistor. When the switch is again closed, the capacitor will cause the transistor base to move toward ground deactivating the relay.

Simple Inverting Buck-Boost Develops −12V

2009-12-05T01:23:00.002+07:00

This is a one simple design for buck booster inverting. This circuit is negative booster inverting. This circuit is based on LM2574. This is the figure of the circuit.

LM2574-12 in a buck-boost configuration to generate a negative 12V output from a positive input voltage. This circuit bootstraps the regulator’s ground pin to the negative output voltage, then by grounding the feedback pin, the regulator senses the inverted output voltage and regulates it to −12V. For an input voltage of 8V or more, the maximum available output current in this configuration is approximately 100 mA. At lighter loads, the minimum input voltage required drops to approximately 4.7V.

Simple Telephone Audio Interface

2009-12-04T03:15:00.002+07:00

This is a simple design circuit for audio from a telephone line that can be obtained using a transformer and capacitor to isolate the line from external equipment. This is the figure of the circuit.

A non-polarized capacitor is placed in series with the transformer line connection to prevent DC current from flowing in the transformer winding which may prevent the line from returning to the on-hook state. The capacitor should have a voltage rating above the peak ring voltage of 90 volts plus the on-hook voltage of 48 volts, or 138 volts total. This was measured locally and may vary with location, a 400 volt or more rating is recommended. Audio level from the transformer is about 100 millivolts which can be connected to a high impedance amplifier or tape recorder input. The 3 transistor amplifier shown above can also be used. For overvoltage protection, two diodes are connected across the transformer secondary to limit the audio signal to 700 millivolts peak during the ringing signal. The diodes can be most any silicon type (1N400X / 1N4148 / 1N914 or other). The 620 ohm resistor serves to reduce loading of the line if the output is connected to a very low impedance.

Simple Single Rail Amplifier With True Zero Volt Output Swing

2009-12-04T03:14:00.000+07:00

This is a circuit that is performance requirements necessitate analog output current monitors to swing within 100mV of zero. This is the figure of the circuit.

A1, a chopper stabilized amplifier, has a clock output. This output switches Q1, providing drive to the diode-capacitor charge pump. The charge pump output feeds A1’s V– terminal, pulling it below zero, permitting output swing to (and below) ground. If desired, negative output excursion can be limited by either clamp option shown. Reliable start-up of this bootstrapped power supply scheme is a valid concern, warranting investigation. In Figure D2, the amplifier’s V– pin (Trace C) initially rises at supply turn-on (Trace A) but heads negative when amplifier clocking (Trace B) commences at about midscreen.

Simple LED Photo Sensor Circuit

2009-12-04T03:12:00.002+07:00

This is a circuit for sensing that takes advantage of the photo-voltaic voltage of an ordinary LED. This is the figure of the circuit.

Simple Inductor Circuit Based APD Bias Supply

2009-12-04T03:08:00.002+07:00

This is a circuit for inductor circuit using fly back technique. This circuit is simplest form. This circuit is work with based on LT1946 as switching regulator. This is the figure of the circuit.

The transformer has been replaced with a 2-terminal inductor. The circuit is a basic inductor flyback boost regulator with a single important deviation. Q1, a high voltage device, has been interposed between the LT1946 switching regulator and the inductor. Q1, operating as a “cascode” with the LT1946’s internal switch, withstands L1’s high voltage flyback events. [Circuit’s source: Linear Technology Notes].

Simple AC Current Indicator Light Circuit

2009-12-04T03:07:00.002+07:00

This is design of indicator that is used to indicated AC current. This circuit could be wired into a 120vac power line, which feeds power to any load, ranging from 40 watts to 250 watts. It will turn on a LED light whenever current is being drawn by a load. It is especially useful for remote lights, where you may not be able to see if the lamps are receiving power. This is the figure of the circuit.

This circuit is built with low components. Consists of diode and resistor and displaying the indicator using lamp.

Simple Current Monitor Circuit

2009-12-03T14:26:00.000+07:00

This is a simple design circuit to approaches attempt to address the current monitor problem. There are two types for this circuit. This is the figure of the types of current monitor circuit.

In figure (1), this circuit uses an instrumentation amplifier powered by a separate 35V rail to measure across the 1kW current shunt. In figure (2), this circuit is similar but derives its power supply from the APD bias line. Although both approaches function, they do not meet APD current sensing requirements. APD bias voltages can range to 90V, exceeding the amplifier’s supply and common mode voltage limits. Additionally, the measurement’s wide dynamic range requires the single rail powered amplifier to swing within 100mV of zero, which is impractical. Finally, it is desirable for the amplifiers to operate from a single, low voltage rail. [Circuit’s source: Linear Technology Notes].

Simple 18 Watt Power Supply

2009-12-03T14:22:00.000+07:00

This is a design circuit for simple 9 Volt 2 amp supply using a single IC regulator. This is the figure of the circuit.

The circuit will work without the extra components, but for reverse polarity protection a 1N5400 diode is provided at the input, extra smoothing being provided by C1. The output stage includes C2 for extra filtering, if powering a logic circuit than a 100nF capacitor is also desirable to remove any high frequency switching noise.

Simple Level Control and Attenuator

2009-12-02T01:16:00.000+07:00

This is a design circuit for the level control, buffer and attenuator. This circuit is control using transistor. The buffer stage is used to ensure that the impedance seen by the attenuator is low, regardless of the pot setting. This is the figure of the circuit.

This is a simple form circuit. This arrangement is not as elegant as some others I have seen, but is quite acceptable and introduces little distortion. The loss introduced by this stage is about 0.05dB, which can be considered negligible. The BC559 transistor will need a small heat sink, as it is operating at a current of about 12mA, so dissipation is 140mW. The level control is a single gang linear pot, and as shown, the attenuator provides a passably constant output impedance of 560 Ohms at all output settings. If desired, the output can be calibrated in Volts, with the ranges 3V, 300mV, 30mV and 3mV. Attenuator accuracy is very good, provided 1% resistors are used for all ranges.

Simple 20 Watt Switcher Forward Converter

2009-12-02T01:15:00.000+07:00

This is design circuit for step-down regulator can be developed using the LM2577 Simple Switcher IC in a forward converter topology. This design allows the LM2577 IC to be used in step-down voltage applications at output power levels greater than the 1 A LM2575 and 3 A LM2576 buck regulators. This is the figure of the circuit.

Diodes, DR and DF, used in the secondary are 5A, 30V Schottky diodes. The same diode type is used for Dc, however a lower current diode could have been used. A compensation network of Rc and Cc optimizes the regulator’s stability and transient response and provides a soft-start function for a well-controlled power-up. [Circuit source: National Semiconductor Notes].

Simple Voltage Follower with Input Compensation

2009-11-30T15:25:00.002+07:00

This is a simple form circuit for implementation the function of the LM12 IC. This circuit is shown the LM12 is prone to low-amplitude oscillation bursts coming out of saturation if the high-frequency loop gain is near unity. This is the figure of the circuit.

The R2C2 combination across the input works with R1 to reduce feedback at high frequencies without greatly affecting response below 100 kHz. A lead capacitor, C1, improves phase margin at the unity-gain crossover frequency. Proper operation requires that the output impedance of the circuitry driving the follower be well under 1 kX at frequencies up to a few hundred kilohertz.

Simple Transient Voltage Circuit

2009-11-30T15:24:00.003+07:00

This is a design circuit transient voltage that is built by LM340. This is a simplest form design. The figure of the circuit is shown in below.

If transients exceed the maximum rated input voltage of the device, or reach more than 0.8V below ground and have sufficient energy, they will damage the regulator. The solution is to use a large input capacitor, a series input breakdown diode, a choke, a transient suppressor or a combination of these. [Circuit source: National Semiconductor Notes].

Simple Remote Sensor

2009-11-30T15:22:00.002+07:00

This circuit is shown a simple design for sensing the remote. This circuit allows the op amp to correct for dc drops in cables connecting the load. This is the figure of the circuit.

This circuit is work with based on LM12 IC. The cable drop will affect transient response. Degradation can be minimized by using twisted, heavy-gauge wires on the output line. Normally, common and one input are connected together at the sending end. [Schematic’s circuit source: National Semiconductor Notes].

Simple Regulator Floating Ground

2009-11-30T15:21:00.002+07:00

This is a design for simplest form circuit the regulator. This circuit is control by LM340. This is the figure of the circuit.

When the ground pin alone becomes disconnected, the output approaches the unregulated input, causing possible damage to other circuits connected to VOUT. If ground is reconnected with power “ON”, damage may also occur to the regulator. This fault is most likely to occur when plugging in regulators or modules with on card regulators into powered up sockets. Power should be turned off first, thermal limit ceases operating, or ground should be connected first if power must be left on.

Simple Parallel Operation for Power Amplifier

2009-11-30T15:18:00.002+07:00

Output drive beyond the capability of one power amplifier can be provided as shown here. This circuit is work with based on LM12 IC. This is the figure of the circuit.

The power op amps are wired as followers and connected in parallel with the outputs coupled through equalization resistors. A standard, high-voltage op amp is used to provide voltage gain. Overall feedback compensates for the voltage dropped across the equalization resistors. With parallel operation, there may be an increase in unloaded supply current related to the offset voltage across the equalization resistors. More output buffers, with individual equalization resistors, may be added to meet even higher drive requirements.

Simple 80W Operational Amplifier Using LM12

2009-11-30T15:13:00.001+07:00

This is a circuit for op amp that is built by LM12. This circuit can deliver 80W of sine wave power into a 4X load with 0.01% distortion. This is the figure of the circuit.

The IC delivers g10A output current at any output voltage yet is completely protected against overloads, including shorts to the supplies. The dynamic safe-area protection is provided by instantaneous peak-temperature limiting within the power transistor array. The turn-on characteristics are controlled by keeping the output open-circuited until the total supply voltage reaches 14V. [Circuit’s source: National Semiconductor Notes].

Simple DC to DC Converter Circuit

2009-11-25T10:08:00.003+07:00

This is a circuit for converter voltage. This circuit is DC to DC converter using a standard 12 VAC center tapped power transformer wired as a blocking oscillator. The circuit is not very efficient but will produce a high voltage usable for low power applications. This is the figure of the circuit.

The input battery voltage is raised by a factor of 10 across the transformer and further raised by a voltage triple consisting of three capacitors and diodes connected to the high voltage side of the transformer. The circuit draws about 40 milliamps and should operate for about 200 hours on a couple of 'D' alkaline batteries. Higher voltages can be obtained by reducing the 4.7K bias resistor.

Simple 12V to 120V Inverter Circuit

2009-11-25T09:57:00.001+07:00

This is a simple design for inverter that produces 12V to 120V voltage and frequency line. This circuit is work with based on the transistor. The wattage depends on which transistors you use for Q1 and Q2, as well as how "big" a transformer you use for T1. The inverter can be constructed to supply anywhere from 1 to 1000 (1 KW) watts. This is the figure of the circuit.

The easiest and least expensive way to get a large T1 is to re-wind an old microwave transformer. These transformers are rated at about 1KW and are perfect. Go to a local TV repair shop and dig through the dumpster until you get the largest microwave you can find. The bigger of the microwave is the bigger transformer. Remove the transformer, being careful not to touch the large high voltage capacitor that might still be charged. If you want, you can test the transformer, but they are usually still good. Now, remove the old 2000 V secondary, being careful not to damage the primary. Leave the primary in tact. Now, wind on 12 turns of wire, twist a loop (center tap), and wind on 12 more turns. The gauge of the wire will depend on how much current you plan to have the transformer supply. Enamel covered magnet wire works great for this. Now secure the windings with tape. That is all there is to it. Remember to use high current transistors for Q1 and Q2. The 2N3055's in the parts list can only handle 15 amps each. Q1 and Q2, as well as T1, determine how much wattage the inverter can supply. With Q1, Q2=2N3055 and T1= 15 A, the inverter can supply about 300 watts. Larger transformers and more powerful transistors can be substituted for T1, Q1 and Q2 for more power. The capacitor is using tantalum.

Part:
C1, C2 - 68 uf, 25 V Tantalum Capacitor
R1, R2 - 10 Ohm, 5 Watt Resistor
R3, R4 - 180 Ohm, 1 Watt Resistor
D1, D2 - HEP 154 Silicon Diode
Q1, Q2 - 2N3055 NPN Transistor (see "Notes")
T1 - 24V, Center Tapped Transformer (see "Notes")

Simple Single Op Amp Band Pass Filter

2009-11-24T10:54:00.001+07:00

This is a circuit design for a band pass filter. A band pass filter passes a range of frequencies while rejecting frequencies outside the upper and lower limits of the pass band. The range of frequencies to be passed is called the pass band and extends from a point below the center frequency to a point above the center frequency where the output voltage falls about 70% of the output voltage at the center frequency. This is the figure of the circuit.

The filter bandwidth (BW) is the difference between the upper and lower pass band frequencies. The quality factors, or Q of the filter is a measure of the distance between the upper and lower frequency points and is defined as (Center Frequency / BW) so that as the pass band gets narrower around the same center frequency, the Q factor becomes higher. For a single op-amp band pass filter with both capacitors the same value, the Q factor must be greater than the square root of half the gain, so that a gain of 98 would require a Q factor of 7 or more.

Simple Multiple Pulse Generator Circuit

2009-11-24T10:48:00.003+07:00

This is a circuit for generate the pulse of timer circuit. This circuit is used to ring my doorbell rapidly three times when a car pulled into my driveway. This circuit is based on 555 timer IC. This is the figure of the circuit.

R2 and C2 set the output frequency. Use a diode and resistor to change the duty cycle, if desired. R1 and C1 set the cycle time which sets the number of pulses. R3 can be deleted if you have other loads on the power supply. The circuit is activated by applying power to it. The first pulse will be longer than the others.

Simple Inverter for Florescent Lamps

2009-11-24T10:46:00.001+07:00

This circuit is very easy to construct, reliable, and even powerful enough to light up a 15W florescent tube. This circuit is constructs from transistor NPN and some components. This is the figure of the circuit.

This is a single transistor oscillator circuit. Current passed through primary winding inducts a magnetic field to the core and the core gives the energy back to the feedback winding with a delay determined by the core material and windings. System then oscillates continuously on a frequency depending on this timing. You cannot use 2SD882 with voltages over 4.5 volts. It is only needed if you are going to feed the circuit with only 4.5 volts.

Simple 555 Pulse Generator

2009-11-24T10:40:00.002+07:00

This is another circuit for generate the pulse of timer circuit. The first positive pulse from a classic 555-based oscillator is always 1.6 times longer than the following pulses. The difference is caused by the fact that only during the first cycle C2 starts charging up from 0 V. This is generally not a problem, but sometimes this first pulse just should be the same length as the rest - at least approximately. This is the figure of the circuit.

The picture shows the oscillator and an addition to it (everything to the right from the Vs-Gnd axis) that can solve the problem. Immediately after switch-on, C2 is empty and the voltage on the gate of Q2 is low. Q2 is off and it makes C2 charge up very quickly through Q1 and R3 until it reaches just below Vs/3. Then Q2 turns on, Q1 turns off, and the classic circuit continues to charge and discharge C2 relatively slowly between 2Vs/3 and Vs/3. As the voltage on C2 never again drops below Vs/3, Q2 now conducts all the time and Q1 is permanently off.

Active Band Pass Filter

2009-11-24T10:31:00.001+07:00

Active band pass filters are simply filters constructed by using operational amplifiers as active devices configured to simulate inductors or what are known as "gyrators". Active band pass filters are used largely at audio frequencies where otherwise the size of the inductor would become prohibitive.

The are many different types of active filters including high pass, low pass, band reject and there are numerous responses including multiple feedback band pass (MFBP), dual-amplifier band pass (DABP) and, state variable bi-quad all pole circuits. Interestingly all known filter responses such as Butterworth and Chebyshev may be synthesised.

Simple Line Driver Circuit

2009-11-11T01:09:00.002+07:00

This is a design circuit for stereo line driver for feeding long cables or buffering an audio source. This is a simple circuit design. This circuit is a pre amp. This is the figure of the circuit.

This preamplifier has low output impedance, and is designed to drive long cables, allowing you to listen to a remote music source without having to buy expensive screened cables. The very low output impedance of around 16 ohms at 1KHz, makes it possible to use ordinary bell wire, loudspeaker or alarm cable for connection. The preamplifier must be placed near the remote music source, for example a CD player. The cable is then run to a remote location where you want to listen. The output of this preamp has a gain of slightly less than one, so an external amplifier must be used to drive loudspeakers.

Simple 22 Watt Audio Amplifier Circuit

2009-11-11T01:07:00.002+07:00

This is a design for simple audio power amplifier. This circuit is based on amplifier chip TDA1554 that is has two channel audio chip amp. This is the figure of the circuit.

The circuit can be used as a booster in a car audio system, an amp for satellite speakers in a surround sound or home theater system, or as an amp for computer speakers. The circuit is quite compact and uses only about 60 watts. The circuit works best with 4 ohm speakers, but 8 ohm units will do. The circuit operates at 12 Volts at about 5 Amps at full volume. Lower volumes use less current, and therefore produce less heat.

Part:
R1 39K 1/4 Watt Resistor
C1,C2 10uf 25V Electrolytic Capacitor
C3 100uf 25V Electrolytic Capacitor
C4 47uf 25V Electrolytic Capacitor
C5 0.1uf 25V Ceramic Capacitor
C6 2200uf 25V Electrolytic Capacitor
U1 TDA1554 Two Channel Audio Amp Chip
MISC Heat sink for U1, Binding Posts (For Output), RCA Jacks (For Input), Wire, Board

Simple Voltage Regulator using Op Amp

2009-11-09T12:29:00.002+07:00

This circuit is a circuit diagram power supply. Circuit diagram works on voltage +13.8 V 5A with electric currents. This circuit controlled by the LM338 IC. This is the figure of the circuit.

Many times we need a supply of relatively strong in the framework we provide a variety of equipment with + 13.8V, as transceivers CB, cargo lead-acid batteries, and others known to use the circuit capable of providing complete in his exit, when This continuously operating 5A and 12A peak current. Not only need a few external components. Setting the voltage at + 13.8V to the trimmer TR1, (multiturn). The IC1 LM338 must in each case is placed on one suitable heat sink, which both supported by one fan. All the connections by the circuit become with big cross-section cable, because the current through from within their already high enough.

Part:
R1=270R 1/4W 2%
TR1=4k7 (Multiturn)
C1=10000uF 40V
C2-3=100 nF 100V Polyester
C4-5=10uF 25V
D1-2=1N4002 (1A/100V)
B1=25A Bridge Rectifier
IC1=LM338
T1=220Vac/15VAC – 8A Mains Transformer
S1=2 Pole Single Throw Mains Switch

F1=250mA Fuse

Simple Pierce XTAL Oscillator Circuit Using JFET

2009-11-09T11:53:00.001+07:00

This circuit is conventional “Pierce” type oscillator that uses a JFET. The circuit uses fundamental mode crystals. It has decent performance and reliability if we use a low noise JFET. This is the figure of the circuit.

The feedback is controlled by the C1 Capacitance from drain to ground. Adjusting the frequency can be done by adjusting a shunt capacitance C2 across the crystal. The crystal works in parallel mode. This circuit is suitable where some crystals should be switched in and out to select the frequency, as there’s no tuning required.

Simple LED Current Sense Circuit

2009-11-09T11:51:00.002+07:00

This is a design circuit for the physical implementation of the LED current sense circuitry assuming the thermal fold back circuitry is a simple current source. This circuit is based on the LM3424 uses an external current sense resistor (RSNS) placed in series with the LED load to convert the LED current (ILED) into a voltage (VSNS). This is the figure of the circuit.

The HSP and HSN pins are the inputs to the high-side sense amplifier which are forced to be equal potential (VHSP=VHSN) through negative feedback. For matching and noise performance, the suggested signal current ICSH is approximately 100 μA. This current does not flow in the LEDs and will not affect either the off-state LED current or the regulated LED current. ICSH can be above or below this value, but the high-side amplifier offset characteristics may be affected slightly. [Circuit’s Source: National Semiconductor, Inc]

Simple HF Bands QRP Linear Amplifier

2009-11-09T11:46:00.001+07:00

This is the design for QRP linear amplifier with a wide frequency response; within three dB's from 300KHz to 30MHz. Overall gain is in the region of 16dB and the final output power may be well over four watts. This is the figure of the circuit.

The wide bandwidth is a result of the construction of the RF transformers, T1 and T2. These are wound on 2-hole ferrite balun cores as commonly found in the old fashioned valve TV sets (e.g. Phillips 4322-020-31520). Twist 2 lengths of 22 SWG enamelled wire together and wind as shown. Connect the end of the "A" winding to the start of the "B" winding. Use this junction as the centre-tap of the transformer. This PA will deliver 4 watts continuously (with a suitable heatsink), and may be loaded into a short-circuit or open circuit without causing damage. This makes it almost the ideal PA for outdoor/field use. Above is the full circuit diagram of the RFPA and the coil winding pattern. This PA may be used for for SSB, as well as CW (and AM?).

Simple FET Audio Mixer Circuit

2009-11-09T11:42:00.001+07:00

This is a simple project circuit for mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consume very little power. This is the figure of the circuit.

This circuit is based on or built by FET 2N3819. The circuit can be powered by a single 9 volt battery. As many or as few channels as are required can be added to the mixer. A shielded case is probably needed to reduce hum and help stop oscillations.

Part:
R1, R3 10K Pot
R2, R4 100K 1/4 W Resistor
R5 6.8K 1/4 W Resistor
C1, C2, C3 0.1uF Capacitor
Q1 2N3819 Junction FET
MISC Wire, Shielded (Metal) Case, Phone or Other Plug For Output

Simple Automatic Nicad Battery Charger Circuit

2009-11-09T11:25:00.001+07:00

Many cheap battery chargers usually assume that charging the battery slowly is OK although the battery is already full of charges. All they do is usually charging the battery with constant current no matter if the battery is almost completely discharged or has been fully charged. Off course the battery wouldn’t be damaged immediately after few charging cycles, but actually they’re damaged slowly and the life time can’t be maximized. This is one of solution for the problem above.

This circuit is automated that you don’t have to manually set the alarm timer to wake you up when your battery has been fully charged so you can unplug the charger to prevent overcharging. This battery sense the voltage while charging the battery, and automatically stop the charging when it’s fully charged. This is the figure of the circuit.

To set the R8, turn the variable resistor R8 to its maximum value (highest resistance), connect a fully charged Nicad battery (about 1.44V) to the batteryn terminal. Press and release the start push button, and make sure the LED D1 is turned on after releasing the start push button. Now turn the R8 slowly toward its minimum value and stop turning exactly when the LED D1 turned off. Now your automatic Nicad battery charger is ready. Place a discharged battery and press the start button, the D1 LED will turn on to indicate that the charging is in progress. LED D1 will turn off after the battery has been fully charged. To provide multiple battery charging, make few more similar circuits shown in the dashed line box, and you can charge up to ten Nicad battery (50 mA charging current per battery) using 1 Ampere 9-12 volts transformer.

Simple Audio Power Amplifier Over Temperature Detector

2009-11-09T11:22:00.000+07:00

This is a power amplifier for audio that has over temperature detector inside. This circuit is based on LM56 as controller. This circuit has simple form of the design. This is the figure of the circuit.

An audio power amplifier IC is bolted to a heat sink and an LM56 Celsius temperature sensor is mounted on a PC board that is bolted to the heat sink near the power amplifier. To ensure that the sensing element is at the same temperature as the heat sink, the sensor's leads are mounted to pads that have feed through to the back side of the PC board. Since the LM56 is sensing the temperature of the actual PC board the back side of the PC board also has large ground plane to help conduct the heat to the device. The comparator's output goes low if the heat sink temperature rises above a threshold set by R1, R2, and the voltage reference. This fault detection output from the comparator now can be used to turn on a cooling fan. The circuit as shown in design to turn the fan on when heat sink temperature exceeds about 80°C, and to turn the fan off when the heat sink temperature falls below approximately 75°C. [Circuit source: National Semiconductor, Inc Notes].

Simple Transistor Tester Circuit Device

2009-11-07T13:36:00.000+07:00

This non transistor tester circuit devices that isn’t accurate, but utility of this test device enough assisting in assaying of quality of transistor. This circuit can show promise about condition of a transistor is still in condition either or have been in condition of breakdown. Besides, earns also applied to test amplification of current from the transistor is categorizing transistor type A (amplifier of current 140 - 270), transistor type B (270 - 500), or transistor type C (amplification > 500).

This very simple circuit work principle. Transistor tested receives bases current around 10mA through R1. With assumption that transistor is still be good, the thing will yield strain at R2 until R4 and depend on position of switches S2, some of this voltage compared to to a reference voltage by utilizing IC 1. Mode of action from circuit which its inside is also approximately equal, only inside of circuit destined for PNP transistor. The supply of the voltage is required by this circuit only from battery.

Wein - Bridge Oscillator Using TLV2471

2009-11-07T13:34:00.001+07:00

The Wien - Bridge oscillator is one of the simplest and best known oscillators and is used extensively in circuits for audio applications. The figure in the below shows the basic Wien bridge circuit configuration. On the positive side, this circuit has only a few components and good frequency stability. The major drawback of the circuit is that the output amplitude is at the rails, which saturates the op-amp output transistors and causes high output distortion. This is the figure of the circuit.

The Wien – Bridge oscillator circuit is shown in the figure, with component values selected to provide an oscillation frequency of ù0 = 2ðf0, where f0 = 1/(2ðRC) = 1.59 kHz. The circuit oscillated at 1.57 kHz, caused by varying component values with 2.8% distortion. This high value results from the extensive clipping of the output signal at both supply rails, producing several large odd and even harmonics. The feedback resistor was then adjusted ±1%. Figure 9 shows the output voltage waveforms. The distortion grew as the saturation increased with increasing RF, and oscillations ceased when RF was decreased by a mere 0.8%.

Touch Switch Circuit Using Logic Control

2009-11-07T13:30:00.000+07:00

This is a touch circuit that is used as a latching circuit to switch a LED ON and OFF by physically touching the ON metal plate or OFF metal plate. This circuit is based on logic gate for control the operation. This is the figure of the circuit.

It is important to ensure that 9V battery is used as its DC source. If one uses the mains supply to step down the voltage using a transformer for rectification and filtering to get the 9V DC supply, ensure that the transformer is designed in such a way that it follows the safety standard requirement of UL. This is important to ensure the safety of the user that is using the metal contacts to ON/OFF the LED. [Schematic diagram source: Electronics Project Design].

Simple Remote Doorbell Warning Switch Circuit

2009-11-07T13:29:00.001+07:00

This circuit should only be used with the solenoid type chime doorbells, the electronic type that play tunes will not work here. This is the simple circuit design.

The basic principle work is the hardest part for this circuit was the title. It is quite easy to miss the sound of a doorbell if you are watching the television, this circuit gets round the problem by providing a visual indication, i.e. a lamp. As an alternative, a LED could also be used. You could just parallel a lamp across the doorbell, but this would mean extra drain from the doorbell batteries or transformer. Using a series resistor R1 actually reduces current flow, and if run from batteries, will give them a longer life. The value of R1 is chosen so that about 0.6 to 0.7 volts is dropped across it, and the doorbell should still ring. I used a combination of a 22 ohm resistor in parallel with a 50 ohm. The doorbell still rang and circuit operated correctly. I used to have an electromechanical counter that registered each time when someone pressed the switch.

Simple Car Battery Charger Circuit

2009-11-07T13:28:00.001+07:00

This is a circuit for battery charger. But the circuit can places in a car. This is a simple design and useful to make it. In this circuit there is facility for monitoring the charging current and voltage. This is the figure of the car battery charger.

The circuit is based on the IC MC78T12ABT. The IC is nothing but a 7812 in TO-3 package with 3A capacity. The transformer T1 steps the mains voltage to 15V AC and diodes D1&D2 does the job of rectification. The transformer T1 can be a 230V primary; 15-0-15V, 3A secondary step down transformer. Capacitor C1 does the filtering and C2 acts as a decoupling capacitor. The ground terminal of IC1 is lifted to 2.1V using the diodes D3, D4 and D5. So the output from the IC1 will be a regulated 14.1V (12+2.1).The battery is charged via diode D6.The D6 blocks reverse flow of current from battery to charging circuit when the mains power is not available.

Simple Amplifier Using LM386

2009-11-07T13:27:00.001+07:00

This is the low frequency power amplifier of which the penumbra article can be composed without using it is hardly. The about 660-mW output can be gotten with the 16-ohm speaker.

This circuit is used for the simple monitor and so on. The impedance (4-ohm and 8-ohm, and so on), the output power of the speaker and so on are specified by the standard but are OK rather than strict. Because the sound cracks (warping) when presenting the output above the rating, it uses naturally within the standard. When conscious of the timbre and the output power, it is better not to do the use of this circuit.

LCD Thermometer Circuit with LM35

2009-11-07T13:23:00.000+07:00

The LM35 of National Semiconductors that is used in this project is a precision centigrade temperature sensor, which has an analog output voltage. It has a range of -55ºC to +150ºC and an accuracy of ±0.5º C. The output voltage is 10mV/ºC. The output voltage is converted by the AD convertor of the AT Mega8. The temperature is displayed on an LCD module. This is the figure of the circuit.

In this example the thermometer has a range of 0ºC to 40ºC and a resolution of 0.5ºC. If you want to have a read out in Fahrenheit you can use the LM34. The software for this project is written in BASCOM AVR. The BASCOM AVR compiler has build in commands for reading out the ADC port of a AVR microcontroller. The result is displayed on a LCD module in a discrete value of the temperature and in a bar-graph. The AT Mega8 has a A/D converter which can give an output of 210 = 1024 discrete values. When a 5V supply is used you have a resolution of 5000mV/1024 = 4.8mV. Because the LM35 has a output of 10mV/C the resolution of the thermometer is 10mV/4.8mV ~ 0.5ºC. The LCD module has 20 columns. In the scale of 0ºC to 40ºC every column represents 2ºC. [Circuit’s Source: National Semiconductor, Inc].

Integrator Circuit

2009-11-07T13:19:00.000+07:00

Integrator op-amp this circuit also comes from inverting circuit with the feedback prisoner is changed with capacitor. This is the figure of the Integrator Circuit.

Usually circuit for application there are addition of parallel prisoner with capacitor with name of RF. Integrator circuit which has not in adding parallel prisoner with capacitor. ROM Value is between zero up to R1.

Simple 8 Watt Flouroscent Lamp Driver

2009-11-07T13:14:00.000+07:00

This is a design circuit of a simple flouroscent lamp driver circuit based on two transistors. The circuit uses capacitive ballasting for driving the tube. An 8 Watt standard flouroscent tube can be efficiently driven using the circuit.

The two transistors (2SC1983) with associated components form an oscillator around 1KHz. The oscillator is wired so that saturation conditions of the transistors are prohibited. This adds on to the efficiency of the circuit. The circuit produces a clean sine wave with very less noise. The winding details (no of turns) are given in the circuit. Use 0, 8 mm diameter enameled copper wire for primary and 0, 4 mm diameter enameled copper wire for secondary. The primary should be wound first and secondary on top of it. The circuit is use a 12 V battery or 12 V DC power supply as the DC voltage source.