This circuit is the factory version of the LM386 low-power amplifier. The sound quality is excellent, and the power can be supplied with voltages from 6 to 16 V.
The circuit shown in the figure consists of a 200mA low voltage drop (LDO) regulator using the...
This circuit was found in an American documentation from the 60's. The transistors are from the...
Found in old documentation, this timer uses a sensitive relay and a 2N2646. The time is given by...