This circuit is from a 90s American documentation. The circuit can use complementary pairs according to the power. The power voltage can be between 5 and 12 V.
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...