This old fashioned transistor amplifier was found in a publication of the year 1958. Transformer are the critical components in the circuit and power comes from 6 D cells.
Found in documentation from the 1980s, this circuit makes use of discrete components of the time....
We found this transmitter circuit that has a very high gain stage for an electret microphone...
We found this circuit in a 2001 documentation. It is safe, as it uses an isolation transformer and at the...