This simple circuit to monitor the frequency of the power grid uses an analog indicator. The adjustment trimpot can be 4k7 and the indicator is 100 mA full scale.
Obtained from a 1996 documentation, this circuit uses common components and has a voltage gain of 200...
This precision circuit can provide timings from 0.2 milliseconds to 3 minutes accurately. The...
Found in RCA documentation from the 90s, this bass and treble control uses an operational...