This circuit with different colored indicator LEDs has an expanded scale. We found it in the March 1992 Radio Electronics magazine. For an adjustable range of 0 to 10.5 V.
This amplifier with differential input uses two old op amps but can be implemented with modern op amps....
This power supply was found in the December 1970 issue of Radio Electronics magazine. The...
This circuit is a wireless temperature transmitter for RF signals in the range of 0.2 to 2 MHz...