This circuit was found in General Electric documentation from 1968. The circuit uses triac from the time as well as transistors that can be replaced by modern equivalents.
This circuit was obtained from an old American documentation, and practically any general-purpose transistor...
This circuit is intended for monitoring an environment. It fires a relay with a sound, but only if...
This circuit is from an old documentation, but perfectly current. In place of the battery, 2 or 4...