This circuit generates the busy tone of ordinary telephones. The transistors can be the BC548 and the components of the T filter and the multivibrator can be changed to obtain the exact tone.
This is one of the first circuits published on this component. We found it in the September 1950...
Found in American documentation from the 90s, this circuit uses a high voltage relay and has no...
This circuit generates high voltage pulses, which can reach 30 000 V with the discharge of a...