This circuit was found in a 1965 General Electric manual. What it does is give a warning if you leave the vehicle with the headlights on or lights inside.
This circuit has a low level at its output (pin 8) when the input signal has a frequency of 10...
Found in a 1993 Electronics Experimenter Handbook, this circuit uses a multimeter to measure...
The circuit is from an old American publication. We can mount it with the BC548 and TIP31. The...