Clap switch circuit is not new idea for the electronics hobbyist. Previously we had posted a simple clap operated switch. Now, here is a clap switch circuit using 555, used to control any appliance by clapping five times. We used here decade counter for right clap code i.e. only right clap activate the appliance (five claps within the preset tome interval 10 seconds).
Description of Clap Switch Circuit Using 555
The clap switch circuit using 555 is build around timer IC 555, decade counter IC CD 4017, few transistor, MIC and few passive components.
The MIC1 (condenser microphone) is used here as sensor, senses the clap sound and further convert it into electrical signal. The output electrical signal from MIC1 is so week that it needs amplification; this work is done by transistor T1. The amplified output from the collector of transistor T1 is given to pin 2 of IC1 (NE555), configured in monostable mode. The trigger from amplifier produce clock pulse at output of pin 3 of IC1. Glowing LED1 indicate the clock pulse at output pin 3. The output from pin 3 of IC1 is given to clock pin 14 of decade counter IC2 (CD4017). Firstly, when the power is given to clap switch circuit, the output from pin 3 is high and glow LED2, glowing LED2 indicates that the switch is ready for use. At this time all other output of clap switch circuit are low. The output from pin 1 is used for activating the appliance via relay RL2.
At each clock (generated from each clap), the output of IC2 gets incremented. The output from pin 2 of IC2 is used to activate IC3 configured in monostable mode. The output from pin 3 of IC3 is used to drive relays through driver circuit build around transistor T3.
IC3 acts as monostable multivibrator (timer) with a time period of approximately 10 seconds, which provides delay time to turn on an appliance even after completing the five claps before the preset time of 10 seconds. The reset pin 15 is connected to contacts of relay RL1 for the preset time of 10 seconds.
When all the five claps are applied within 10 seconds, the outputs at pin 1 of IC2 goes high and relay RL2 energized to turn on the appliance just after the de-energization of relay RL1. The table 1 shows the On/Off condition of the appliance for every clap. In wrong clap code, the high output of IC2 reset it via its pin 15 and the appliance doesn’t turn on.
On/OFF status of the appliance for every clap
Relay 1 (RL1)
Off after 10 seconds
PARTS LIST OF CLAP SWITCH CIRCUIT USING 555
Resistor (all ¼-watt, ± 5% Carbon)
R1 = 10 KΩ
R2 = 470 KΩ
R3 = 100 KΩ
R4, R5, R11 = 1 MΩ
R6 = 220 Ω
R7 = 470 Ω
R8, R9, R12 = 1 KΩ
R10 = 22 KΩ
R13 = 150 KΩ
VR1 = 1 KΩ
C1, C2 = 0.1 µF (Ceramic Disc)
C3 = 1 µF/16V (Electrolytic Capacitor)
C4, C6 = 0.01 µF (Ceramic Disc)
C5 = 10 µF/16V (Electrolytic Capacitor)
IC1, IC3 = NE555 (Timer IC)
IC2 = CD4017 (Decade Counter IC)
T1 = BC549
T2 – T4 = BC548
D1, D2 = 1N4007
D3 – D10 = 1N4148
RL1 = 9V, 150Ω, 2C/0 Relay
RL2 = 9V, 150Ω, 1C/0 Relay
MIC1 = Condenser Microphone