We found this circuit in the October 1970 issue of Radio Electronics magazine. It uses the then-new CA3018 integrated circuit from RCA. Some resistors are required for best performance.
This circuit was found in a 90s Popular Electronics. The emitting lamp that has very poor response to...
This circuit is from an ancient American documentation. The integrated circuit is 741 and the...
This circuit was obtained from an American publication from the 60's. The transistors are...