Greetings everyone,
I have a simple(I think) problem that I just can't figure out. I have two goals. The first is to become knowledgeable with transistors. Does anyone know of a good video/book that I can learn the basics of transistors from? I really appreciate any help.
The second goal is to build a circuit that has two LED's and tests for an open/closed in a cable. Schematic is attached. I have a cable with 6 separate conductors that I want to test whether there is an open or short in. I want a green LED to light when there is a short and the red LED to light if the wire is open. I thought I had a nice little circuit but it didn't work on the breadboard. It did, however, work in the spice simulator. I am not sure how to calculate the base resistor values for transistors, so I'm sure that adds to my problems. On the breadboard, one LED lights just fine, but when I create an open at the base of the first transistor, both LED's light. I am assuming that the base-emitter junction in the second transistor is letting enough current through to light the first LED. In the schematic, the cable under test would be at the base of the first transistor (on the left) with 9v going into one side of the cable and the other end to the transistor base. I want to learn as much as I can from this project. Again, thank you all for any input/suggestions you can provide. It is much appreciated.