Amplifier Timer


Posted on Oct 30, 2012

Turns-off your amplifier when idle for 15 minutes Fed by amplifier tape-output. This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. Pushing P1 the device is switched-on feeding any appliance connected to SK1. Input audio signal is boosted and squared by IC2A & IC2B and monitored by LED D4. When D4 illuminates, albeit for a very short peak, IC3 is reset and restarts its counting. Pin 2 of IC3 remains in the low state, the two transistors are on and the relay operates.


Amplifier Timer
Click here to download the full size of the above Circuit.

When, after a 15 minutes delay, no signal appeared at the input, IC3 ends its counting and pin 2 goes high. Q1 & Q2 stop conducting and the relay switches-off. The device is thus completely off as also are the appliances connected to SK1. C5 & R9




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Synchronous System
3 Channel Color Organ Circuit
7-MHz Loop Antenna
DTMF Decoder 2
ISL6291 Li-ion/Li Polymer Linear Battery Charger
Doorbell Cascade
Portable Battery Charger Using Renewable Energy Sources like Solar or Wind Project
Coupler Crystal Radio
PIC Frequency Counter with Frequency Lock
Halogen Lamp Dimmer With Soft Start
Separately excited DC motor reversing circuit



Top