This circuit from Popular Electronics powers a small speaker. The transistor can be of general use and the capacitors can be altered to change the sound generated.
This is a shunt circuit to be used on a multimeter, expanding its scales to measure high currents....
This circuit from an old documentation includes the power supply for the 117 V power grid. It can be...
Although MOSFETs of the type indicated are not very easy to obtain, one can have the circuit as a...