Top Circuits Page 175
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This versatile amplifier circuit is designed and submitted by Mr Seetharaman Subramanian from Chennai. The full credit of this article goes to him and we are very proud to publish this fabulous circuit here. This concept has appeared long back in Practical....
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A simple multi-channel audio mixer circuit using LM3900 quad amplifier is given below. The circuit consists of 4 channel quad amplifier (LM3900). Two mic audio inputs and two direct line inputs are available in this circuit. By adding the same circuit....
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Here is a simple circuit that will produce a musical horn when ever your car is in reverse gear. The circuit uses two ICs for the operation, voltage regulator 7805(IC1) and musical tone generator UM66(IC2). The IC1 reduces the car battery voltage to 5V. The....
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Here is a simple circuit diagram of a simple musical horn using two NE555 ICs. Two ICs are wired as astable mutivibrators. The output of first multivibrator is given to the discharge (pin 7) of the second astable multivibrator. The combined effect of the....
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A simple musical light chaser circuit diagram and schematic using IC CD4016. This simple circuit blinks light according to sound/audio/music output and as a result 10 lights dance according to sound frequency....
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The working of Negative Resistance Oscillators,Types like Dynatron,Tunnel diode oscillator, their characteristics and circuit diagram is explained....
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This is the circuit diagram of a very powerful and efficient Ni-MH battery charger using IC LT4060 from Linear Technologies. In addition to Ni-MH batteries Ni-Cd batteries can be also charged by slightly modifying the circuit. For charging Ni-Cd batteries....
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This simple circuit is build around a CMOS IC 4060 to obtain the required timing. During day time the LDR has low resistance and keeps the pin 12 of the IC1 high, preventing the IC1 from oscillating. When it is dark the LDR resistance becomes high and the....
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This is of course the simplest electronic code lock circuit one can make. The circuit uses one transistor, a relay and few passive components. The simplicity does not have any influence on the performance and this circuit works really fine. The circuit is....
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Working, schematic diagram and design of uA741 IC op-amp comparator circuit with inverting, non-inverting comparator waveform is provided....
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A feedback amplifier having closed-loop gain, Af greater than unity can be obtained by the use of a positive feedback. This result also satisfies the phase condition and thus results in the operation of an oscillator circuit. An oscillator circuit then....
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This simple circuit can be used as an aid for sensing the distance between the rear bumper of the car and any obstacle behind the car. The distance can be understood from the combination of the LEDs (D5 to D7) glowing. At 25cm D7 will glow, at 20 cm D7&D6....
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Tone control circuit using opamp and a baxendall passive tone control circuit. Overall gain is 25db with 20db boost & cut. Powered using 15V dual supply....
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LM339 based peak detector circuit.Simple and easy to construct. Operates from 5V DC single supply. LM339 is a dual comparator....
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We select the so called phase shift oscillator as a first example as it exemplifies verysimply the principles set forth in the previous blog post. The circuit is drawn to show clearly the amplifier and feedback network. The circuit consists of a common....
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A photo relay or light activated relay is a circuit which opens and closes the relay contacts according to the light. Here a photo diode is used to sense the light. The photo diode offers a high resistance when there is no light falling on it. Here the photo....
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A simple photo switch circuit using NE 555 IC with diagram and schematic.This photo switch ons a relay when light intensity crosses limit.A light sensor circuit for home and industrial purpose....
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PIR (Passive Infrared Radial) Sensor Based Security System, circuit diagram,working,applications....
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Phase Locked Loop (PLL) Operating Principle with block diagram showing Phase Detector, Voltage Controlled Oscillator, Low Pass Filter....
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The circuit given here produces an alarm similar to the police siren. When you press the push button switch S2 capacitor C1 will charge and this will make the transistor Q1 to ON slowly. When the switch S1 is released the C1 will discharge and the transistor....
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A lot of electronic circuits using NE555 timer IC are already published here and this is just another one. Here is the circuit diagram of a police siren based on NE55 timer IC. The circuit uses two NE555 timers ICs and each of them are wired as astable....
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This circuit diagram shows how to obtain a negative voltage from a positive voltage supply. Another advantage of this circuit is that, the negative voltage together with the original positive supply can be used to simulate a dual supply. The circuit is based....
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Just about any power transistor can be used in this megaphone. Its suitable for boats, playing fields etc. the transistors Q1 & Q2 are the HEP-230 type which are easily available in the market. The transistors are parallely connected to handle the required....
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This is the circuit diagram a powerful LED flasher. High power LEDs are very common in the market now and a 1W high power LED is used here. Transistors Q1 and Q2 are wired as an oscillator which produces positive pulses of width 20ms @ ½ Hz. Transistor Q3....
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Simple proximity detector circuit based on NE567 IC. Circuit switches an LED when the object comes near the sensor....
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This is a simple circuit in which the glowing LED can be switched OFF just by a puff. A condenser mic (M1) is used to sense your puff. When the push button S1 is pressed, the transistors Q2 and Q3 wired as latching pair gets activated and drives the LED to....
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As already explained, a monostable multivibrator (MMV) has one stable state and one quasi-stable state. The circuit remains in its stable state till an external triggering pulse causes a transition to the quasi-stable state. The circuit comes back to its....
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Simple PWM inverter circuit using SG3524. This PWM inverter circuit has 12V input, 220V output and 250 watt output power. Output power can be extended....
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Simple PWM lamp dimmer using NE555 timer IC. 555 timer IC wired as variable duty cycle astable multivibrator for controlling the brightness of the lamp....
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A simple PWM motor speed control circuit with diagram and schematic for low power dc motors. This easy to make pwm dc motor controller is made using IC CD40106B....
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This circuit is designed as per a request made by Mr Vinoth from India. His requirement was a 12V/5A DC fan motor controller. I think this circuit is sufficient for this purpose. Quad 2 input Schmitt trigger IC CD4093 is the heart of this circuit. Out of the....
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We know that every inductor coil has a certain amount of resistance and the coil should have lowest possible resistance. The ratio of the inductive reactance to the effective resistance of the coil is called the quality factor or Q-factor of the coil. A high....
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Low power ( 3 to 30 MHz) transmitters constructed by hams are generally called QRP`s. For such transmitters a well tuned antenna is a must. If the impedance is not properly matched there will be a little or no output. But if properly matched there will be....
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This a very simple and inexpensive circuit that can be used to test quartz crystals. Here a Colpitts oscillator is wired used the transistor T1. When the crystal is connected between terminals A and B the circuit will produce high frequency oscillation. The....
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This is a radio transmitter circuit diagram suitable for fitting on radio collars using NE 555 IC. he circuit transmits a pulse in the FM between band 88MHz to 105Mhz....
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The rain alarm circuit working is explained in detail. The rain alarm project is explained with circuit diagram....
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Simple random number generator using 8051 microcontroller. AT89S51 is the controller used here....
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The drawbacks of pi-filters are the comparatively larger cost, more weight, bigger size and external field developed by the series inductor. However, these drawbacks can be overcome by replacing the series inductor by a series resistor R. Such a circuit is....
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The circuit given here is of a regulated dual power supply that provides +12V and -12V from the AC mains. A power supply like this is a very essential tool on the work bench of an electronic hobbyist. The transformer T1 steps down the AC mains voltage and....
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This is a simple type remote control by using RF communication without microcontroller. In this project a remote has been designed for various home appliances like television, fan, lights, etc. It gives lot of comfort to the user since we can operate it by....
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A simple remote control tester circuit with diagram and schematic using infra red sensor IC TSOP1738. An LED will blink when IR waves falls on it which indicates remote control functioning....
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Here is a remote operated spy robot circuit which can be controlled by using a wireless remote controller. It can capture audio and video information`s from the surroundings and can be sent to a remote station through RF signals. The maximum range is 125....
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When the telephone rings the line voltage rises to 72 volts. At this time the LED in the opto-coupler glows and the transistor conducts. Due to this the transistor Q1 conducts. This makes the relay ON. The load connected to the relay whether bulb or bell....
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RMS value of the sinusoidal waveform is meas ured by the average reading voltmeter of which scale is calibrated in terms of rms value. This method is quite simple and less expensive. But sometimes rms value of the non-sinusoidal waveform is required to be....
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A sawtooth wave generator circuit using a 555 IC is given in the article below.Frequency equation is given with the supply voltage Vcc....
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Sawtooth wave generator using NE555 and opamp uA741. NE555 is wired as square wave generator and opamp is wired as integrator.Circuit diagra, and working theory....
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Apart from the timing functions, the two comparators of the 555 timer can be used independently for other applications. One example is a Schmitt Trigger shown here. The two comparator inputs (pin 2 & 6) are tied together and biased at 1/2 Vcc through a....
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A scoring game circuit is explained with circuit diagram, and circuit parts....
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SCRs are sensitive to high voltage, over-current, and any form of transients. For satisfactory and reliable operation they are required to be protected against such abnormal operating conditions. Because of complex and expensive protection, usually some....
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A timer circuit using IC 4060 is given here. The IC 4060 is a 14 stage binary counter with a built-in oscillator. R2, R7, C1 are the components that determine the frequency of the oscillator and the outputs will become high one after other and only one at a....
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When S2 is ON, the circuit here operates as an astable multi vibrator and the LED is lit for about o. 1sec, flasing every 1. 5 seconds. Since the human reaction time is more than this, you cannot catch it once it is seen o, by pressing S1. If your sense of....
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This is the circuit diagram of a very sensitive electromagnetic field sensor which can sense electromagnetic field from 40Hz to 140Hz. The low noise opamp LF351 and associated components forms the pick-up section. 1uH coil L1 is used for sensing the field....
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In this arrange ment a high value inductor or choke L is connected in series with the rectifier element and the load, as illustrated in figure. The filtering action of an inductor filter de pends upon its property of opposing any change in the current....
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Here is a simple shock sensitive alarm circuit that has many many applications fro home to automobiles. The main application of this circuit is to use it as an anti theft alarm in automobiles. A peizo electric sensor is used as the shock sensor which has to....
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The circuit given below is of a simple audio amplifier that can deliver 12W to an 8 Ohm speaker. Op amp IC TL081 is used as the preamplifier here. Actually any opamp with matching power supply ratings can be used instead of TL081. Transistors Q1 and Q2....
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An article on How to make an inverter using simple 40 Watts inverter circuit diagram and schematics. This is a 12 volts to 220 Volts inverter using CD4047 IC....
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This is a very simple AM radio circuit using only two transistors. The coil L1 and variable capacitor C1 forms the tank circuit. Transistor Q1 does the job of demodulation. The demodulated signal will be available at the base of Q1. This audio signal is....
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A 12V battery full charging circuit with simple diagram for rectifier is given.The lead acid trickle charger circuit is explained with a rectifier....
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A simple burglar alarm circuit diagram and schematic. This can be used as anti theft alarm by attaching the burglar alarm circuit to window foil....
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The circuit diagram shown here is of a simple DC power delay circuit that is based on an SCR. This circuit is a very handy one and can be employed in many applications. The working of this circuit is very simple. When the input power is applied the capacitor....
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A tone generator circuit,which can be used to make a simple calling bell circuit is shown here.It is made using 8021 IC which has built in ding dong sound producing circuitry....
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This is the circuit diagram of a simple electronic combination lock using IC LS 7220. This circuit can be used to activate a relay for controlling (on & off) any device when a preset combination of 4 digits are pressed. The circuit can be operated from 5V to....
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A simple function generator circuit using LM1458 is known here. LM1458 is a dual general purpose operational amplifier. The two opamps inside LM1458 has a common bias network, power supply line and are independent of each other in operation....
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Here is a simple IR audio link that can be used to transmit audio signals up to 4 meters. The signal to be transmitted is applied to the base of Q1 via resistor R4. The transistor Q1 drives the IR transmitting diodes D1 and D2. The audio input will be....
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A fan regulator circuit which can also be used as a simple lamp dimmer circuit.This fan speed regulator or light dimmer is based on power control using triac....
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A low cost,simple radio circuit schematic using op amp.This radio circuit diagram consists of a sensitive audio amplifier which receives strong signals....
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A simple proximity detector (sensor) circuit diagram and schematic is shown and how to make it using proximity detector IC CS2009A-used for metal detector applications....
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This is the circuit diagram of a simple UPS that can deliver 12V unregulated and 5V regulated DC. The transformer T1 steps down the mains voltage to 12V AC and then the bridge B1 rectifies it. The rectified signal is smoothed by the capacitor C1. When the....
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A simple Water level indicator project with circuit diagram for home and industry.This water tank level sensor can be used for any liquid level indicator projects....
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This is a very simple lamp flasher circuit that uses only three components (a capacitor, relay and one resistor) other than the lamp. The working of the circuit is very straight forward. When the power is switched ON the capacitor C1 charges through the....
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A simple FM Radio circuit with diagram and schematic using IC TDA 7000. This low cost single chip fm radio circuit design is easy to make and is suitable to make a FM portable radio....
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A simple Single chip FM transmitter circuit with diagram and schematic using IC MAX 2606, which is a high performance Voltage controlled oscillator or VCO....
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This is a simple single chip metal detector circuit based on IC CS209A from the Cherry Semiconductors. A 100uH coil is used to sense the presence of metal. The IC CS209A has a built in oscillator circuit and the coil L1 forms a part of its external LC....
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Many audio mixer circuits have been published here. But I think, this one is the simplest of them. This very simple audio mixer circuit uses only one transistor. The base emitter junction of the transistor is biased by the diodes D1 and D2. The signals to be....
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Here is the circuit diagram of a simple radio that uses one transistor and few other passive components. The C6 and L1 forms a tank circuit which picks up the signal from your desired radio station. Diode D1, capacitor C2 and resistor R1 does the detection....
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Software delay routine in 8051 for generating different time delays. Sine wave generator circuit using software delay in 8051. AT89C51 is the microcontroller used in this project....
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A sound level meter circuit with diagram and schematic using IC LM 3915,which is an audio level measurement chip.Used to display amplifier sound level or a microphone sound level....
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Here given is a circuit in which the status of the output pins of a Flip Flop IC can be toggled by using sound. A condenser microphone is used for picking up the sound. The first two op-amps in the IC1 LM 324 is used to amplify the sound picked by the....
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Here is a simple circuit that can be used to check the sound levels. The sound pressure meter is vey useful in setting up home theater systems, if you need to test the sound pressure of each channels on different positions in the room. The circuit is nothing....
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When the amplifier is switched on, the speaker gets popped up by a high voltage and you can hear a loud thud sound from the speaker. This stuff is very harmful to the speaker and it drastically reduces the speaker`s life. The circuit shown here connects the....
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This circuit is a simple approach for converting a loud speaker into a microphone. When the sound waves fall on the diaphragm of a speaker, there will be fluctuations in the coil and there will be a small proportional induced voltage. Usually this induced....
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This circuit given here can be housed in the box containing the speaker to form a handy microphone amplifier. The device can be used by teachers, guides, lecturers etc for speaking in a crowdy or noisy environment. The circuit is designed base on the audio....
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Here is a simple circuit for controlling the speed of DC operated PCB drills. The heart of this circuit is the ICLM3578 which is a very efficient integrated switching regulator that can be used for applications like this. The LM3578 has separate inverting....
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The non-sinusoidal waveform generators are also called relaxation oscillators. The op-amp relaxation oscillator shown in figure is a square wave generator. In general, square waves are relatively easy to produce. Like the UJT relaxation oscillator, the....
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Square wave generator using uA741. Circuit diagram, theory and working principle....
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The circuit shown here is of a simple 0 to 9 display that can be employed in a lot of applications. The circuit is based on asynchronous decade counter 7490(IC2), a 7 segment display (D1), and a seven segment decoder/driver IC 7446 (IC1). The seven segment....
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A simple dc to dc step up voltage converter circuit schematic using LM2700-which is a step up switching converter....
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Here is the circuit diagram of a simple stepper motor controller using only elementary parts. The driver circuit uses, four transistor (SL100) to drive the motor windings, two NOT gates and one XOR gate to decode the two bit control logic to drive the four....
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The circuit diagram given here is of a stepper motor driver using MC3479 from Motorola. The MC3479 is specifically designed for driving a 2 phase stepper motor in bipolar mode and is available in standard DIP and surface mount packages. The IC is compatible....
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This is one of the simplest stereo balance indicator circuit that you can have. The circuit will give a visual indication (using two LEDs) proportional to the difference in balance between the left and right channels of a stereo system. The circuit is based....
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Simple FM stereo decoder circuit using MC1310P IC. 12V operation, 40dB channel seperation. Suitable for stereo FM receivers....
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A simple and high quality FM transmitter circuit designed based on the BA1404 IC .This FM transmitter circuit can be operated from a 3 V battery....
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Here is the circuit diagram of an excellent stereo preamplifier with tone control using the IC TDA1524 from Phillips. The IC requires very few external components, has very low noise and has a wide power supply voltage range. POTs R1 to R4 can be used for....
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Stereo VU meter / 2 channel audio level meter using IC TA7666P. Volume level of each channel is displayed using 5 LEDs .This loudness meter uses minimum number of external componets....
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The circuit diagram of an Automatic Street Light Controller Circuit is explained in this post....
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Here is the circuit diagram of an opamp based subwoofer filter. Audio frequencies below 200Hz are considered to be in the subwoofer range. So a subwoofer filter will be essentially a low pass filter with a cut off frequency of 200Hz. The working of this....
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Here is the circuit diagram of a super bright LED night lamp that can be operated from the mains supply. Bridge D1 is used to rectify the AC mains voltage. The capacitor C1 and resistor R1 forms the current limiting circuit. 10 ultra bright white LEDs are....
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Here is the circuit diagram of an ultra sensitive intruder alarm. The shadow of an intruder passing few meters nearby the circuit is enough to trigger the alarm. Here IC2 uA 741 is wired as a sensitive comparator, whose set point is set by R6 &R7. The....