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.
This circuit was found in an ancient American documentation. The transformer is the type used in...
This circuit generates two pulses per cycle of alternating voltage for full wave control. The...
To increase the control capacity of the CA3140, an amplifier circuit can be used, as shown in the...