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.
This circuit was found in a 1987 edition of the United States' Hands-On Electronics magazine. The...
We found this circuit in an old English publication. The resistor not indicated can be 2k2 and the...
This circuit was found in a Popular Electronics from the 90s. It uses a LASCR which is a photo-SCR...