This circuit was found in Radio Electronics from the 90s. The transducer is a tweeter and the power transistor must have a heatsink.
This circuit is intended to reinforce old car radios, having been found in 1997. At that time,...
The Sample and Hold circuit shown in the figure was found in a 1994 Linear Applications Handbook by...
Found in a 1980s documentation, this circuit detects when the voltage drops below 11 V. Other...