We found this circuit in the September 1995 issue of Electronics Now magazine. The circuit has 6 scales for resistance measurements and uses an analog indicator from 50 uA to 1 mA.
This adjustable source was found in a 1979 documentation, but all components are still common...
This temperature control was found in General Electric documentation from the 90's. The circuit uses...
This SCR circuit was found in an American 1980s documentation. The circuit is still current,...