The circuit shown is from National Semiconductor's Linear Applications Handbook. It makes use of the LM78S40 which is not an easy component to obtain today.
This circuit has appeared several times on this site in different applications. This is from 1997...
This circuit allows you to use a digital multimeter as a thermometer. The sensor is mounted in a...
This alarm circuit was found in a 1989 Poptronics, but all the components used are common, as the...