Free circuit schematics - wiparat.com

As friends many take an interest the circuit about IC 555 which be integrated highly popular that circuit. I then lead the circuit sets the time be Basic Timer Control with NE555 come to present again. By it basically the base of the circuit sets the time work instruction easily initial. Press S1 for a [...]

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 [...]