This circuit was obtained in the 1990 Motorola Linear Databook. The circuit uses a 139 series comparator, but other series can be used. The power source need not be symmetric.
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...