The purpose of this circuit is to test NPN and PNP transistors and to identify their pin layouts, ie ECB, EBC. I find myself testing a lot of transistors to determine their pin layout and type and as such find that building the test circuit on a breadboard has become a hassle so I wanted an easy circuit that would be more permanent and would allow me to test transistors.
The transistor type NPN/PNP determines the polarity of the connections. The orientation of the transistor is the pin layout. I define the pin layout when looking at the top of the transistor with the flat side facing toward you. That is probably not the official way to classify them but it makes more sense to me when I am placing them in a circuit.
- EBC stands for Emitter Base Collector. When I use this acronym I am saying that the pin to the left is the emitter, the middle pin is the base, and the right pin is the collector.
- ECB similar to the above acronym stands for Emitter Collector Base. The emitter pin is again on the left but the middle pin is the collector and the right pin is the base.
I have gone through about 100 transistors that were pulled from old electronics and have never found any other orientations so i have found that there is no need to test for anything but these two orientations.