Sound-activated-switch


Posted on Oct 27, 2012

Al and A2 are two sections of a quad comparator. The first, Al, functions as an amplifier and detector. Resistors R~and R6 set the gain at 100; the output of Al is an open collector to negative-peak-rectify the output with a decay time constant determined by R9 and C3. This de output is then compared with the reference level selected by RB.


Sound-activated-switch
Click here to download the full size of the above Circuit.

A2 triggers switch Ql, and an LED inserted in the base drive of Ql gives visual indication of switch closure. The standby battery drain is 2 mA. Use potentiometer R8 to select the desired sensitivity.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

16 LED Chaser
Wideband two-pole high-pass filter
low cost high speed photography
U-110 1.5 Mhz Current Mode Ic Controlled 50-watt Power Supply
Water level indicator using 7-segment display circuit design
100Hz-1MHz a circuit diagram of the phase meter



Top