# Voltage doubler circuit using NE555

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Description. The circuit diagram of a very simple voltage doubler using NE555 timer is shown here. Here IC NE555 is wired as an astable mutivibrator operating at around 9KHz. The base of the two transistors (Q1 and Q2) is shorted and output of the astable multivibrator (pin 3) is connected… Read more »

# Variable frequency oscillator

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Description. Here is a simple variable frequency circuit based on timer NE555. Here NE55 is wired as an astable multivibrator, whose output frequency can be varied by varying a potentiometer. This circuit is a must in the work bench of a electronic hobbyist. Frequencies ranging from several Hz to several… Read more »

# USB sound card

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Description. Designing and building a USB sound card is no longer a head ache because we have got the PCM 2702 integrated circuit from Texas Instruments. The PCM2702 is an integrated 16 bit digital to analog converter that has two digital to analog output channels. The integrated interface controller of… Read more »

# Tweeter Crossover circuit

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Tweeter Crossover Circuit Description A single coil speaker is not good in handling high and low frequency at the same time. If we could filter out the low frequency and play it through a tweeter ,it will produce more sound quality than using a single speaker.This is what is realized… Read more »

# TV antenna booster

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Description. The circuit shown here is of a TV antenna booster based on the transistor BF180. The circuit operates in the UHF band and has a gain of 15dB. Capacitors C2,C3 C4 ,C5 and inductors L3, L4 forms a UHF band pass filter. The input signal is fed to the… Read more »

# Transistor Amplifier Circuit-12 Watts

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12 Watts Transistor Amplifier Circuit Description. The circuit shown below is not at all expensive as the amplifier contains only an op-amp and four transistors (easily available from your electronics junk box).Here the op-amp used is uA 741 which produces the required gain.The four transistors are wired as complementary Darlington’s… Read more »

# Transformerless power supply circuit

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Transformerless power supply Description. Here is a low cost and simple circuit that can be used to power up small electronics devices. The power is directly tapped from the mains via resistor R1.D1 rectifies the voltage and C1 and C2 are used to filter the output.The zener diode D2 keeps… Read more »

# Touch switch using CD4011.

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Description. A simple touch switch circuit using CD4011 is given here. The IC CD4011 is wires as a flip flop here. The 9, 13 pins of the IC works as the set and reset contacts respectively.CMOS ICs like 4011 require requires a very low current for controlling its gates. Since… Read more »

# Touch Dimmer for Lamps

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Touch Control Lamp Dimmer Description This is a simple touch dimmer circuit made of IC TT6061 . TT 6061 is specifically designed for this purpose.By touching this touch dimmer you can increase the light intensity of incandescent lamps in three steps At first, when mains is Ã¢Â€Â˜on,Ã¢Â€Â™ the lamp is… Read more »

# Three phase auto changer circuit

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Description. The circuit given here is designed by Mr.Seetharaman V.S (seethasub@hotmail.com) from Chennai. Seetharaman’s comments about the circuit: This circuit is a modification of High & Low voltage cut-off with delay& alarm circuit appeared in Circuits today, which I have tried and found to be quite reliable. You can adopt… Read more »