Category Archives: Fun Circuits



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 »

220V Light Dimmer

This simple 220V light dimmer circuit can be used to adjust the brightness of mains lights. It also can be used to adjust the speed of AC motors. It uses a triac, diac and has a radio-frequency interference (RFI) noise suppression circuit built into it as well. Schematic diagram: Components List: R1 = 10K R2… Read More »

Sound Activated Switch

This is a sound activated switch circuit. It’s will turn on and turn off based on a loud sound such as clapping your hands. You can adjust the sensitivity (how loud of a sound will activate the circuit) from a pin drop to a Mack Truck Horn. Very practical for a variety of projects. Add… Read More »

220V LED Flasher

This is a 220V LED flasher circuit which is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. This a low cost circuit and easy to built since it only use little amount of electronic components.. Schematic diagram: Component Parts: R1_________ 100K R2,R5______ 1K R3,R6______ 470R R4_________ 12K C1_________ 1000uF 25V… Read More »

3V Lamp Brightness Controller

Here’s the 3V lamp brightness controller circuit diagram used to control the brightness of the light bulb. You simply use the two AA or AAA battery to make this circuit works. Example usage of this circuit is to adjust the brightness of images for close-up photo shoot with a digital camera. IC1 works to generate 150Hz… Read More »

Motor Speed Control with MAX4295

This is a motor speed controller circuit diagram built based MAX4295 from Maxim. By using this circuit, you will be able to control the speed of motor movement. Resistor R1 biases the potentiometer to match the input range of U1. Full counter-clockwise rotation of the pot corresponds to maximum-speed reverse rotation of the motor. Mid-scale… Read More »

Wailing Alarm Siren

Here is the wailing alarm siren circuit diagram: Components List: R1,R5___________ 4.7K R2______________ 47K R3______________ 10K R4______________ 100K Rx______________ *see text C1,C4__________ 100uF/25V, electrolytic C2,C3__________ 0.01uF (10nF), ceramic T1_____________ 2N3702 (NTE159, TUP, etc.) IC1,IC2________ LM/NE555, MC1455P, etc LS_____________ Loudspeaker