This circuit, with printed circuit board included, is from a Radio Electronics magazine from July 1971. The SCR can be any equivalent of the 106 series.
This circuit is from a publication from the 70s. The operational amplifier is from the period. Modern...
We found this circuit in the October 1992 issue of Radio Electronics magazine. The duty cycle can...
This circuit digitally counts input pulses. The circuit from a November 1970 Radio Electronics uses...