This resistance meter circuit was found in the February 1984 issue of Radio Electronics magazine. It is based on a digital module from that time. The power supply is 5 V.
This oscillator from a 1970 documentation uses an operational amplifier that is no longer common on...
The integrated circuit used in this 90's circuit is not common today, but the configuration can be...
Found in a 70s RCA manual, this circuit uses a transistor of the time for an UHF L band...