This is the circuit for the HM-10ª, an instrument sold by Heathkit. The circuit is from a Radio Electronics from May 1963. The indication is by an analog instrument.
This circuit was found in a March 1988 Radio Electronics. The voltage scale is set at R3. 19 LEDs...
The idea of this circuit found in a Radio Electronics from January 1966. The idea of the...
This circuit was found in a 1974 publication. It provides a tone indication of the temperature sensed by...