This is a battery powered 3W power amplifier using germanium transistors. The circuit is from an English documentation from 1967. The transistors are from the time.
CMOS inverters can be used as amplifiers, obtaining a flat response up to approximately 20 kHz....
The maximum time interval of this circuit depends on C1. Larger values can be used to get closer to...
This sonic relay or vox was found in a Popular Electronics from the 90's. The power MOSFET can be of...