This circuit, for vehicles with a 6 V battery, was found in the 1964 RCA transistors manual. Transistor 2N3054 can be replaced by a TIP41.
The circuit shown consists of a simple tester for general purpose silicon or germanium diodes and...
This circuit was found in a 1987 documentation but uses components quite common in the current...
This configuration was found in a 1990s documentation. Modern operational amplifiers can be used...