Page 1 Top Circuits

1W Linear FM Booster

1W Linear FM Booster

That RF Amplifier is for boosting small fm transmitters and bugs. It use two Philips 2N4427 and its power is about 1Watt. At the output you can drive any linear with BGY133 or BLY87 and so on. Its power supply has to give 500mA current at 12 Volts. More voltage can boost the distance but the transistors will be burned much earlier than usual.! In any case do not exceed the 15Volts. ..

8 Watts Audio Amplifier (TDA2003)

8 Watts Audio Amplifier (TDA2003)

Nice small audio amplifier which use only few parts to give good quality sound. This amp can be used as a simple booster, the heart of a more complicated amplifier or used as a guitar amp. Although not perfect, this amplifier does have a wide frequency response, low harmonic distortion about 1.5%, and is capable of driving an 8 ohm speaker to output levels of around 8 watts with slightly higher distortion. ..

TBA820 Amplifier

TBA820 Amplifier

A very useful audio amp in an 8-pin DIL package. The IC features a very low minimum working supply voltage of 3V, low quiescent current, good ripple rejection, no crossover distortion and low power dissipation...

Water Softener Circuit

Water Softener Circuit

That circuit is based at a technique to remove or neutralize the salt in water, and protect the pipes at home as well as the washing machines or our selves from salt. Its called water softener and its automated circuit using two 555 timers. ..

2 Watts FM transmitter

2 Watts FM transmitter

This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter, L2= 1 turn - 10mm diameter. R9 trimmer controls the modulation gain. The tunning is easy by controlling C9 trimmer (88-108 MHz). The RFC J should be the VK220J with ferrite (VK200 is not suitable). ..

FM surveillance BuG Transmitter

FM surveillance BuG Transmitter

The Circuit shown can transmit voice to exceptionally good range. Tune trimmer to hear the signal to your near radio. Frequency range is 88-108 MHz. Max current consumption is 30mA. You can power the bug with a 9Volt Battery, or you can plug a power supply to feed in 9-12 Volts. ..

50W Hi-Fi amplifier with TDA7294

50W Hi-Fi amplifier with TDA7294

The TDA7294 is a Hi-Fi amplifier and can give 100W RMS but with 10% distortion. Supplying 30 Volts you can have 50 Watts RMS with 1% distortion. Frequency range start at 16Hz and can reach 100KHz. Make sure you are using good heatsink. The chip supports mute function as well. ..

TV and FM jammer schematic

TV and FM jammer schematic

The Jammer is a very small circuit and can fit inside a small plastic box with 9V battery inside. It can be very illegal if you attach an external antenna so don't. adjust frequency by turning trimmer...

0-30 Volts / 2,5A Variable Power Supply

0-30 Volts / 2,5A Variable Power Supply

This is a high quality power supply with a continuously variable stabilized output adjustable between 0 and 30VDC. the LM 723 is the heart of the power supply which drives the BD137 and then the 2N3055. The circuit provides short circuit protection. And has great stability at voltage changes. ..

Passive subwoofer filter

Passive subwoofer filter

The schematic shown, does no need any power supply because is a simple low frequency passive filter. It could be usefull if you want to drive an extra subwoofer from your stereo system...

Active Antenna for 10 to 30 MHz

Active Antenna for 10 to 30 MHz

The schematic shown, is a 2 transistor signal amplifier between 10 MHz to 30 MHz. The BF256C and the BF494 are very popular transistors and are easy to find. The transformer works as insulator and amplifier...

Amplifier input signal overdrive auto-protection

Amplifier input signal overdrive auto-protection

That circuit protects the overdriven signals going into an amplifier. Instead of a zener diode we use a transistor. That way we ensure that the above the ordinary input voltages ( 1 volt r.m.s.) can be acheaved without distortion. Also the use of a transistor limits the number of components used in this schematic...

In-Car lights delay circuit

In-Car lights delay circuit

This circuit switch slowly on and off the internal lights in a car. The delaying time can be adjusted changing the values of the 10k, 4M7 resistors and capacitor...

Simple Infra-Red Transmitter/reciever Shematics

Simple Infra-Red Transmitter/reciever Shematics

This 1 channel infrared transmitter/receiver remote control is the cheapest and simplest you can find. The transmitter transmits a sequence of pulses on 36 KHz frequency carrier. The diodes are Schottky type because of their low voltage drop (only 0.2V). The ripple counter 74HC4060 contains an oscillator which controls the frequency carrier to be 36KHz...

Active Antenna Circuit for 10KHz to 100MHz

Active Antenna Circuit for 10KHz to 100MHz

This active antenna schematic can be used to frequency range from 10 KHz to 100 MHz. The length of the Antenna can be between 0.5 to 1 meter long. The power consumption is 20-30mA...