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.
This filter is suggested by the Texas Instruments Linear Circuits Applications, 1986 edition. The...
This CMOS circuit was obtained in a 1980s documentation. The circuit has a 10-second time delay...
This circuit consists of a switched mixer with digital touch control. The circuit was found in old...