This very low power amplifier is designed by Amperex for hearing aids. It is based on TAA370 which is not an integrated circuit that can be found today.
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...