This circuit has an accuracy of 1%. The components used must be precision as well. The input frequency range is 40 Hz to 10 kHz with the indicated components.
This circuit was taken from Maxim documentation from the 1990s. It can be implemented on the basis...
This circuit had its assembly described in Radio Electronics from July 1964. The circuit uses LDRs...
This circuit is from a 1992 publication. The transistors can be the BC549 or BC548 and the power...