24W Audio Amplifier (Class A)

This is the circuit diagram of 24 Watt class A linear audio amplifier, built and tested by Marc Klynhans from South Africa. The supply voltage can be between 34V and 46V and the quiescent current should be set to 1.7A measured through R25 (a voltage of 0.75V must be measured over R25 for a quiescent… Read More »

18W Audio Amplifier

This is the circuit diagram of 18W audio amplifier. The circuit is quite simple and inexpensive to built. It uses a pair of power transistor TIP41A and TIP42A for single channel operation. The power supply used for this circuit is dual polarity (splitted) power supply, use center tap transformer to build this kind of power… Read More »

Diode Zener Tester

This is the circuit diagram of zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. This is a handy circuit and will help you to measure the zener diode easily. This diode zener tester can be fitted in a 9V battery box. 1/3 of the box may be used… Read More »

Digital Variable Resistor / Potensiometer DS1669

The DS1669 is an electronic digital rheostat manufactured by Dallas Semiconductor. This component has a function similar to digital variable resistor/potensiometer which can be operated by push the buttons. You can adjust the audio volume, LCD contrast, frequency, etc. by using two buttons instead of a common potentiometer/trimpot. This circuit explains how we do it… Read More »

220V 800W Lamp Flasher

This is 220V 800W lamp flasher circuit directly connected to 220V mains. One or more lamp which has high consumption / power can be used. It is ideal for signage warning or danger, this circuit flickers the lamps. The work of this circuit is simple. The 400V capacitor, the bridge rectifier, the zener diode and… Read More »

Stereo Tube Amplifier 4 Watts

This is the circuit diagram of stereo tube amplifier using 6SQ7-GT and 6V6-GT. The tube amplifier circuit is uses the total of 5 power vacuum tube. The diagram is based on the output section design of typical late 1940’s old AM Trutone radio with 6 tubes. The output will be 4 Watts per channel (2x4W… Read More »

Car Audio System Anti Theft Security

This is the circuit diagram of car audio system anti theft security which can be effectively used to protect and secure your expensive car audio system from stealing. This simple circuit designed based on popular CMOS NAND chip CD4093,. When the circuit is switched on via switch S1, the indicator LED1 will glow and the… Read More »

Power Supply Failure Alarm

This is the ‘special’ circuit design of power supply failure alarm. The vast majority of the power supply failure alarm / indicator circuits require a independent power supply for themselves. However the alarm circuit introduced right here requires no extra supply power source. It utilizes an electrolytic capacitor to hold sufficient charge, to supply power… Read More »


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