This 4-tube counter was found in Radio Electronics magazine from December 1959. The circuit uses a coil as a sensor to detect the passage of metallic parts or magnets.
This reaper has the signal limit determined by the zener voltage. We found this circuit in a 1980...
This unity gain circuit was found in the February 1995 Electronics Now magazine. The frequency is 10 kHz,...
This reinforcing stages from a 1960s documentation. No information is given about the transformer...