This circuit is from a Radio Electronics from April 1964. The circuit uses power transistors of the time, which must be mounted on a good heat radiator. Modern equivalents can be used.
Based on 4066 CMOS, we found this circuit in a Popular Electronics from 1992. The signal is...
This circuit was used to regulate the speed of small DC motors of cassette recorders. However, if the...
The CUT frequency for this filter is determined by the capacitors. The µA4138 is a quad version of...