This circuit was found in Motorola's 1968 documentation. It can be built on current equivalent components. The bridge diodes and the SCR must be in accordance with the current of the controlled motor.
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...