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.
Using the ULN-3784B this circuit typically supplies 5 W at 24 W. However, it can operate from 9 V....
This circuit, from a former publication of 1968 was originally designed for germanium transistors, but with the...
This circuit simulates an 18-point digital display using light bulbs, but can be adapted to use...