This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
The indicated circuit performs a slow charge of 12 V batteries maintaining a constant current of...
Found in a 73 magazine from the 1980s, this circuit generates signals from 3.2 to 22 MHz. FETs can be...
In the figure we have a three-phase AC motor control for voltages up to 600 V or 1200 V depending on...