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  1. Herschel Peeler

    Transistor to control resistance

    Hi, new to the forum here. Are you still looking for this quest? How complex a circuit is acceptable. Is an op amp, +V, -V, a J-FET and a few parts acceptable? Yes a J-FET was my first thought, too, but a 2N5462 needs about -0.65 V in for 0 ohms and about -0.41 V in for 180 ohms. The attached is...
  2. Herschel Peeler

    Help with resistors

    Just because the LED is rated at 20 mA does not mean you MUST draw 20 mA through it. How much brightness do you really need? It may work just fine for you at 5 mA. Since this is battery powered you will save a bit of battery life at 5 mA. 9 V - 2 V = 7 V. At 5 mA means about a 1500 ohm resistor...
  3. Herschel Peeler

    Hello, Welcome! (Introduce yourself)

    Herschel here. Serious about electronics but not an engineer. I have taught electronics in a slot machine adult school (casino gaming) and wrote a lot of articles for Slot Tech Magazine. As far as I know I am the only author of a text book on slot machines. I started studying electronics in...
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