We found this circuit in a 1980s Motorola documentation. The circuit makes use of common operating and the voltage depends on the used type. The components are for a frequency of 500 Hz.
This circuit for analog video signals was found in the August 1970 issue of Radio Electronics...
This 5-range current measurement circuit was found in the September 1989 issue of Radio...
Oscillators up to some megaherts can be made with comparators like the LM139, 239 or 339. Theses...