Clap Switch Circuit using 555 IC and Relay is small and easy project.
It uses sound like clap to turn ON and OFF the 220V AC things like fan, light etc.
In this post we can help to make each part of clap switch circuit by using 555 timer IC and one relay for this
What is Clap Switch Circuit:
Clap switch circuit that uses 555 IC and relay and this circuit can turn ON and OFF any device just by a clap sound.
It work by catching a sound like clap.
The 555 timer IC work in monostable mode and send signal to a relay and a relay then turn ON and OFF the device connected to it.
Parts List:
| Component | Quantity |
|---|---|
| Resistors (all 1/4 watt unless specified) | |
| 47k | 1 |
| 1k | 1 |
| 100k | 1 |
| 220Ω | 1 |
| Capacitors | |
| Electrolytic 10μF | 1 |
| Semiconductors | |
| 555 IC | 1 |
| Condenser Microphone (Mic) | 1 |
| Transistor BC547 NPN | 1 |
| LED Red 20mA 5mm | 1 |
| Clap Sound Source | 1 |
| Diode 1N4007 | 1 |
| Relay 9V | 1 |
Main part of circuit is 555 IC and it works like astable multivibrator.
Normal frequency of 555 is around 670 to 680 Hz.
But in this setup it work like monostable multivibrator which is also called one-shot multivibrator.
The time of pulse in circuit is control by outside R and C which are resistor and capacitor connected to 555 IC.
Formulas:
Below is formula for Clap Switch Circuit:
Formula for Pulse Time (T):
T = 1.1 × R1 × C1
where:
- T is time of pulse in seconds
- R1 is resistor value in ohms
- C1 is capacitor value in farads
How to Build:
To build a Clap Switch Circuit follow the below steps for connections:
- First connect mic (condenser microphone) to circuit input.
- Mic catches sound and change it to small electric signal.
- Now connect one transistor with mic output.
- When mic hear the sound the voltage connects to transistor base and turn ON transistor Q1.
- Connect transistor output to pin 2 TRIG of 555 IC.
- When transistor is ON then voltage at pin 2 goes low which is less than 1/3 of Vcc and this makes 555 IC start to work.
- Then connect one LED to pin 3 (output) of 555 IC.
- When pin 2 goes low then pin 3 become high and this gives clock pulse inside 555 flip flop and LED turns ON.
Circuit Working:
When sound is made near mic then mic changes sound to electric signal.
This signal connects to base of transistor Q1 and turn it ON.
When transistor turn ON then voltage at pin 2 TRIG of 555 IC goes low and this trigger the 555 IC.
Then output at pin 3 goes high and send clock pulse and LED turns ON.
The flip flop stay in SET state until next sound (next clock pulse) comes.
Clap Switch Circuit with Relay for 220V Appliances:
This circuit uses relay to turn ON or OFF at 220V devices by clap sound.
We can use it to run any 220V load.
Applications:
Clap switch is not only for LED ON/OFF.
It can also work with many electric things like fan, radio or any simple device we want to start with sound.
Conclusion:
Clap Switch Circuit is fun and learning project.
It shows how sound energy changes into electric energy.
It uses simple parts and easy working.
We can use this idea for smart home and other cool electronic projects.