In this project guide, we’re building a Touch Switch Circuit using NE 555 IC. As you know, NE/SE 555 is a very popular timer IC with multiple applications in different projects. A touch switch is basically a simple switching circuit activated upon a touch. If you’re new to 555 IC, please take the time to read our beginner’s guide on 555 IC. Also, you can try many of our applications using 555 timer IC
This is the circuit diagram of a small touch plate controller using IC NE 555.This circuit is ideally useful for making touch operated doorbells, buzzers, toys, etc which when touched on the touch plate operates the relay for a preset time and then turns off automatically.
This circuit is realized by utilizing the high input impedance of the trigger pin of the 555 IC. When the IC is triggered by the induced voltage of the human body the output goes high for a time determined by R1 and C1.The transistor is used to drive the relay. The relay contacts can be used to drive the load like bell, motor, lights, etc.
To make the touch plate cut a 1 square cm thin metal sheet.
To set up the circuit connects to the power supply and adjust R1 while keeping touching on the touch plate. Stop at the point where relay activates. If the relay is in the activated state initially then do the same until the relay is deactivated.
Touch Switch Circuit Diagram