This circuit was obtained from 1967 documentation. It uses a sensor to determine the trigger point. The components are of the time, difficulty to obtain these days.
This circuit was found in a Hands On Electronics from the 90s. The microphone is a small 75-ohm...
The transistor can be any general purpose and the speakers must be 8-ohm or more. The supply can...
This circuit was obtained from an English circuit manual. Components are common and LEDs can be 3...