This traditional signal injector configuration was obtained in a 1977 amateur radio manual. The frequency is given by the capacitors and the supply can be made with 1.5 or 3 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...