This amplifier was found in a 1957 Rayrtheon documentation. The circuit can be fitted with a BC558 transistor. Driver and output transformers can be obtained from unused transistor radios.
We found this circuit in a Popular Electronics of the 90s. The MOSFET can be of any type,...
In fact, the correct name would be a hearing aid amplifier. However, we use the name of the...
This circuit controls a relay causing it to open and close its contacts at a speed that depends on the...