This circuit is from a 1968 Electronic Design. The characteristics of the output transformer are not given and the transistors are of the time. The circuit provides a power of a few watts.
This circuit was found in the May 1989 issue of Radio Electronics magazine. The circuit requires a...
We find this microphone voice effect in 1992 documentation. The vibration of the relay contacts...
This circuit to increase the sensitivity of instruments to 100 uA (or close to it) was found in...