Random circuits

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Simple but reliable car battery tester

This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source.... [read more]

Power amplifier 2X5W with TDA1516Q

A simple STEREO amplifier, with minimal external components. It use one only opamp., that is capable to give output power 2X5W in the 4 ohms, with distortion 0.5%.... [read more]

Digital Roulette with Display

This circuit is a small digital “roulette''. It is constituted by oscillator IC1, the counter IC2, the transistors Q1-7 that drive the display common cathode DSP1. The supply basically becomes from a battery 9V, but can become also from one power supply.... [read more]

Low Voltage, High Current Time Delay Circuit

In this circuit a LM339 quad voltage comparator is used to generate a time delay and control a high current output at low voltage. Approximatey 5 amps of current can be obtained using a couple fresh alkaline D batteries. Three of the comparators are wired in parallel to drive a medium power PNP transistor (2N2905 or similar) which in turn drives a high current NPN transistor (TIP35 or similar).... [read more]

123 Game - All MCU-free

This electronic game pits a human player against the ‘machine’. The opponents use a common ‘game token’ and take turns moving along a path by one, two or three steps, and the winner is the first one to reach the goal exactly. Incredibly enough, this simple version of the ‘123’ game can be built without a microcontroller, and it’s almost impossible to beat.... [read more]

A Cmos Based Vehicle Anti-Theft Alarm

This car alarm circuit features Exit and Entry delays, an instant alarm zone, an intermittent siren output and automatic Reset. By adding external relays you can immobilize the vehicle and flash the lights.... [read more]