This circuit can make use of almost any operational amplifier and the diodes are for general use. It is intended to excite an analog instrument.
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...