This traditional configuration found in a Radio Shack document can use 2N2646. More keys can be added, and the power can be supplied with voltages from 9 to 15 V.
With this circuit it is possible to excite direct current relays from an alternating signal,...
In the figure we have the basic configuration of a rectangular oscillator using an operational amplifier...
This automatic battery charger was found in a Popular Electronics from the 90s. The circuit uses a...