This experiment is a disappointment because it would not work as the work book described. I had to replace the diode for the LED (same circuit as Experiment #44) to get the transistors to flip-flop and have memory. In the video, the blue wire is negative and the red wire is positive. First, I built the circuit with a diode instead of a right LED (how the circuit is described in the book). Next, I show how the circuit reacts to the negative and positive wires. The book stated that applying the positive wire to the off transistor would turn that transistor on. I found that this is not the case. And, I am guessing, but I believe this is because the diode is not passing the current. Second, I replace the diode for the LED and I show how the LED's flip-flop with positive and negative wires. This seems to be closer to what the work book was trying to show. That positive current will switch on the NPN-transistor's and turn off the other NPN-transistor; more over, the transistor would remember that it had been turned on and would stay on. In this sense, the experiment is the opposite of Experiment #44, but at the same time the circuit is the same -- basic multivibrator and bistable switch-- just the experiment is using positive current instead of ground. To conclude, positive current (red wire) will turn on the off transistor just as the on transistor would turn off by ground (blue wire), and have memory of the action. All this is demonstrated in the video; in addition, I included a copy of the experiment from the work book and pictures of the circuit with diode or LED.
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| Circuit with diode as described in work book. |
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| Circuit with LED functions as described in work book. |
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| Work Book Information |
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