Detailed explanation of the working principle of the clapper activated optical circuit

A clap activated light circuit is used to activate or turn on something by a simple clap of your hands. You may have seen some of these before, but building one can be really fun. This clap activated switch circuit can be used for any kind of activation, not just turning on lights. Let's see how this cool circuit works.

Working principle of the clapper activated light circuit:

The working of this circuit starts with a microphone used to sense the clapping. The output of the microphone is fed to the non-inverting pin 3 of a simple operational amplifier. Whereas the voltage divider network using R2 and RV1 provides the reference voltage to the non-inverting pin 2 of the operational amplifier.

Clapping usually occurs in short duration at high pitch, hence in short time intervals a peak voltage is produced across pin 3 of the op-amp. Hence, the reference voltage at the non-inverting pin is adjusted accordingly so that the circuit activates only when clapping is detected and not for other speech signals.

Now, when no tap is detected, there will be no voltage across pin 2, so the output of the op-amp remains in a low state. The pull-down resistor R3 is used to ensure that pin 6 remains low in the absence of any input signal. When a tap is detected, the output of the op-amp goes high and feeds a positive high output to the flip-flop connected to it.

A simple JK flip IC 74109 is used as an activator, it is connected to switch its output state with every edge of the high input. So whenever a clap is detected, the output of the op-amp triggers the flip-flop and activates the relay through the transistor switch. This state will remain until another clap is detected and the flip-flop will switch its output state (i.e. turn off the relay/light) when it encounters another clap.

A simple LED with a current limiting resistor is added as an indication and a 5V relay is used here as an activator for the lighting. You can replace the light with whatever you want to activate it on clapping. Your clap activated light is ready

Notice:

Clap activation must be done by a trial and error method by adjusting VR1 until the light can be activated simply by clapping.

Make sure your switching transistor Q1 is rated for enough current to handle the relay.

You can use any op-amp and JK flip-flop IC here.