This lead-acid battery charger was found in a Popular Electronics from the 90s. The circuit has a maximum current of 2 A, being suitable for powering inverters in emergency lighting systems.
This circuit using an operational amplifier was found in old American documentation. It can be...
If the circuit oscillates, emitting sound, it is because the transistor is good. This simple...
Like the previous circuit, this is used in the analog part of the telephone lines. The same...