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.
Found in a1969’s neon lamp documentation, this circuit uses a high voltage transistor. The output...
This circuit is intended to match impedances for observing signals on an oscilloscope. The FET...
This circuit, shown in the figure, consists of a variable gain amplifier with differential input...