This audio circuit was published in a Rado Electronics issue from October 1963. The transistors are from the time and the output is low impedance. Power is supplied with a voltage of 12 V.
This headphone amplifier using a pickup coil can be used as an extension for devices such as TVs,...
This rapid response amplifier uses an integrated one that is not common today but can be...
This low noise microphone preamplifier circuit was found in American documentation from the 90s....