Sound-Controlled Clap Switch DIY Kit with battery pack

The Sound-Controlled Clap Switch DIY Kit is a fun and educational electronics project that lets you control devices with a simple clap. Designed for DIY enthusiasts, students, and hobbyists, this kit helps you explore audio amplification and bistable circuit technology while providing a practical application for sound-based control. It’s an engaging way to develop soldering skills and learn about electronic components.

Parameters

Kit Model: PSK-1

Operating Voltage: 4.5-5V

PCB Dimensions: 28 × 49mm

Working Principle

Q1 and Q2 form a two-stage audio amplification circuit. The audio signal received by MK1 is coupled through capacitor C1 to the base of Q1. After amplification, the signal is fed directly from the collector of Q1 to the base of Q2, where a negative square wave is generated at Q2's collector to trigger the bistable circuit.

Resistor R1 and capacitor C1 limit the circuit’s frequency response to around 3kHz, which is the optimal sensitivity range. When the power is connected, the bistable circuit starts with Q4 in a cutoff state and Q3 in saturation, leaving D3 off.

When MK1 detects a control signal, it passes through the two-stage amplifier, generating a negative square wave. After differentiation, the resulting negative pulse is applied through D1 to the base of Q3, causing the circuit to flip, turning D3 on. Upon receiving another control signal, the circuit flips again, turning D3 off.

The circuit board includes a J1 terminal for connecting external devices. By connecting a relay via J1, other equipment can be controlled through sound activation. (When connecting a relay, a diode should be placed across the relay coil for reverse polarity protection.)