This circuit is from a Radio Electronics from October 1963. The transistor is a power transistor of the time, and two transformers are used. The input has 10k impedance and is powered by 12 V.
We found this amplifier for automotive use in the Philips integrated circuit manual from 1990. The...
This interesting circuit records a few seconds of audio signals, reproducing them in a small...
Settings like this can be found at various points on this site. The trigger door can be a 4093...