This long interval timer was found in the September 1976 issue of Radio Electronics magazine. The output can be used to control a relay. The circuit achieves timings of up to 14 hours.
This circuit, which presents a certain danger and should be used with caution, was found in the...
This circuit with variable capacitance diode (varicap) is from a publication from the 90s. The...
This circuit, shown in the figure, consists of a variable gain amplifier with differential input...