A Relay Module DIY Kit for the Popular Clap Switch

There is a popular do-it-yourself clap switch kit available on ebay.

It is a very basic clap switch kit that switches on an LED on the circuit board. Many hobbyists are interested in knowing how we can connect a relay in this kit and operate 100-240V AC appliances. For those who have not used the mentioned clap switch, you can follow the links given below:

I have made a relay module that can be connected with the clap switch. It facilitates the switching of 100-240V AC lamps. For example, I have used the kit for switching ON/OFF a tube light operating at 220V AC. Check out this video.

The schematic of the basic kit is available on buildcircuit.com.

The kit is available at this link.

In this article, I am going to show all the steps for making the relay module and using it with the clap switch.

Step 1: Solder the Resistors

Solder 4.7K and 1K resistors.

Color code for 4.7K resistor: Yellow-Purple- Red

Color code for 1K resistor: Brown-Black-Red

Step 2: Solder 1N4001 Diode

This 1N4001 diode is used as transient-voltage-suppression (TVS) diode and it is connected to relay.

Step 3: Solder LM7805, BD139 Transistor and 0.1uF Ceramic Capacitor

LM7805 voltage regulator is used for regulating 5V required for the clap switch. BD139 NPN transistor is used for activating the relay used on the circuit and 0.1uF capacitor is a normal filter capacitor connected between output pin of LM7805 and Ground.

Step 4: Fix SPDT Switch, 2 Pin Screw Terminal and PC817 Optocoupler

SPDT switch is used for switching on/off the circuit. 2 pin screw terminal is used for connecting the power supply. You can connect a 9V battery with a 9V snap connector. The LED inside the optocoupler PC817 activates its internal photo transistor and that eventually switches on the BD139 transistor to activate the relay on the circuit board.

Step 5: Solder the DC Barrel for Connecting Power Supply

Power supply to the circuit can be connected either via 2 pin screw terminal or DC barrel. The circuit requires 6-9V power supply.

Solder the red LED also. It works as power indicator.

Step 6: Solder 5V Relay, 10uF Capacitors and 3 Pin Screw Terminal

To operate AC lamps, we need a relay. So, we fix it on the circuit board and we use a 3 pin screw terminal that connect to the NC, NO and Common/Pole (P) pins of relay. The screw terminal facilitates easy connection of appliances to the relay.

Step 7: Connect the LED Pins of Clap Switch to the Relay Module

The anode and cathode pins of LED on the clap switch has to be connected to corresponding anode and cathode pins on the relay module. When we produce a sound/clap, the clap switch circuit will switch on the LED inside the PC817 optocoupler that eventually activates the 5V relay.

This kit is available at buildcircuit.org.

Step 8: Connect the Power Supply Wire

Connect the JST jumper wire of the clap switch to the + and - points on the relay module(circuit board).The clap switch kit gets power from the relay module kit.

This kit is available at buildcircuit.org.

Step 9: You Clap Switch With Relay Module Is Complete

Simply power up the circuit using a 9V battery. You can use either the 2 pin screw terminal or the DC barrel to supply power to the circuit. The clap switch takes power from the relay module circuit board.

The following image shows how you can connect a lamp to the circuit board.