Category Archives: Misc

Solid State Relay

This is the circuit diagram of solid state relay. In reality, it is not a relay after all. There’s no ‘relay’ found, just the electronics circuit which does the switching. It operates a similar way as a relay; it is possible to use a low voltage to switch a higher voltage or better than ordinary… Read More »

12V Lead-Acid Battery Monitor

This easy circuit makes it possible to monitor the charging process to a higher level. Final adjustsments are simple and easy and the only device required is a digital voltmeter for the important accuracy and reliability. Connect an input voltage of 12.65 volt between the positive and negative poles and adjust the 10K trimmer potentiometer until Led 10 lights up.

Adjustable Sine/Square Wave Oscillator

The following scheme diagram is the circuit diagram of simple easily tuned / adjustable sine and square wave oscillator. With this circuit you can easily generate sine/square wave which can be adjusted both the frequency and amplitude. The circuit uses IC LM101A, a general purpose operational amplifier (op-amp) and IC LM111, a high-speed voltage comparator… Read More »

Insect Repellent

This insect repellent circuit will repel insects such as mosquitoes, flies and cockroaches from your home or yard effectively. circuit uses a specific frequency to disrupt the insect so the insect will go away from this circuit. This insect repellent circuit can be placed inside or outside the home (for speakers). If you want to… Read More »

Tone Detector / Sound Activated Switch

The following circuit diagrams are tone detector circuit diagrams which also known as sound activated switch circuit. Actually, these circuits use microntroller for switching because the circuits were designed for robot start up activation. But you can build switching module using relay. You may make a trial to use this circuit for other applications such… Read More »

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