This simple audio signal tracer or follower can be made with a BC548 instead of the original transistor. The output is made in a small crystal phone. The power can be from 5 to 9V.
This circuit obtains phase-inverted signals from a single signal. The circuit uses two LM741...
This circuit with the HA2400 was found in the March 1980 Radio Electronics magazine. The circuit has...
This circuit with RIAA equalization is from 1985 US documentation. The circuit has a flat response...