The UAA170 integrated circuit is not very common today. This project is for a 303 Circuits from the 90s. The power supply is 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...