Found in a Popular Electronics from the 90s, it applies to the old answering machines that used tapes. It emits a warning beep on the drive.
This circuit generates a high voltage of the order of 250 to 300 V from a 12 V battery to power a...
This circuit triggers an LED when the input signal exceeds the peak, or the value set in RV1. The...
This circuit was found in a 90s European documentation. The circuit already includes a powerful...