Sound-Operated Switch


Posted on Dec 4, 2012

This sound-operated switch will sense the ring of the phone and translate this to a lamp that will go on and off. The


Sound-Operated Switch
Click here to download the full size of the above Circuit.

amplified signal across R2 reaches D1 through capacitor C2. The rectified audio signals provide a negative bias for Q2, a pnp transistor. This causes Q2 to conduct so the current that triggers SCR1 is provided at the gate. Potentiometer R4 sets the sensitivity. R3 and C3 delay the operating voltage for Ql so that the circuit will not be triggered on by the sound of the on/off switch, SI or by the current surge. Set the lamp atop a TV receiver, turn it on and set the potentiometer so that a finger snap at two feet will trigger the lamp on. Place the speaker close to the telephone and give it a try.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Automatic Dual output Bulb Display
Linear light-meter circuit
supernode dependent voltage source
ADC 207 Flash Converting Schematic Diagram
touch switch circuit with 3 transistors
Protection Circuit For Electrical Appliances From Power Supply Variations PCB
Four channels infrared remote controller circuit diagram
The oscillator with electronic tuning of frequency
Basic circuit diagram of a 2.4 GHz radio system-on-chip CC2430
Infrared remote control dimmer light circuit diagram
Coship CDVB3188V receiver switching power supply circuit



Top