This 3 and-a-half digit circuit was found in a Teledyne documentation from the 90s. The circuit uses a thermocouple as a sensor. The integrated circuit used is uncommon today.
The figure below shows an AC transconductance amplifier with the National Semiconductor LM3900. The...
This common circuit using operational amplifiers was found in the 1993 issue of Radio Electronics Special...
This circuit provides a voltage at the output only when the input voltage exceeds a value that...