Found in 90s Popular Electronics, this circuit fires a load through a MOSFET from an audio signal applied to the input. Power supply is done according to the load.
The power transistor of this circuit can also be the TIP42 mounted on a good heat sink. The...
Using a window comparator, this circuit trips over a certain range of input voltages. Formulas for...
This timer circuit was found in a 1980s documentation. The integrated circuit is the 555, which...