Found in a PE Hobbyst Handbook, this circuit checks if there is voltage in a power outlet by emitting sound and lighting an LED.
This oscillator with emitter follower was found in an American documentation from the 80's. The...
We found this circuit in 2005 Linear Technology documentation. The integrated circuit is LT1787...
The circuit is suggested by National Semiconductor in its 1994 Linear Applications Handbook. The...