This 8 ohm output amplifier was found in a 1968 Motorola publication. The circuit uses transistors of the time and is powered with a voltage of 25 V + 25 V.
The sensitive relay reed trigger transistors can be the BC548 and the diode can be the 1N4148. The...
This two-channel wired intercom was found in the April 1990 issue of Radio Electronics magazine....
We found this circuit in a 1967 American documentation. The diodes are general-purpose and the...