The reference voltage for this circuit can be selected digitally. The circuit is from Radio Electronics dated February 1981. The 741 must be powered by a symmetrical source.
Found in American documentation from the 1970s, this circuit employs an integrated circuit from...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This assembly circuit using a small motor as a generator was found in Radio Electroics magazine from...