This circuit is from the time when cars used contact breakers. This 80's version measures the dwell angle of the contact breaker for dwell adjustment using an era integrated circuit, the LM3917.
Exciting buzzers we have the circuit of the figure, which has a modulator by interruption, with a...
This tracker for audio and RF signals was found in old American documentation. Transistors and...
The circuit shown by the figure below can produce signals in the range between 20 kHz and 30 kHz....