This 8 W amplifier with germanium transistors was found in a Japanese documentation from 1967. The circuit is of the commercial type and is powered by two 12 V batteries or by a symmetrical source.
With the coded activation of the relays, it is possible to control which of the 16 outputs...
The integrated circuit used in this application is not very common. Transistors and resistors...
This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are...