This high quality circuit with complementary symmetry was found in an Electronics World of 1966. It can be made with modern transistors like the BD or TIP series.
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...