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  1. B

    Magnetic Pendulum

    I'm trying to make a magnetic pendulum circuit for a holiday decoration, and I need some help. I found this circuit online (see attached JPG), but the circuit behavior is not consistent and it rarely works correctly. Most of the time, the coil is ALWAYS on (rather than momentarily on when the...
  2. E

    Collector feedback and output impedance

    Hi there. I found a website that uses Miller's Theorem to analyze a simple collector biased transistor (voltage shunt feedback). There's something about the ouput Z that I don't understand. https://wiki.analog.com/university/courses/electronics/text/chapter-9#example_972_using_miller_s_theorem...
  3. sr13579

    How to find out if UJT 2N2646 is original or not?

    I bought two UJT (2N2646) before yesterday. I tried to make an oscillator but it was not working. There was a guy from FB who said it could be a duplicate (not original) one. It must be tested. How should I test if it works or not. I googled some and found about diode and resister testing. But...
  4. E

    Solid-state audio amplifier complexity vs valve/tube

    This posts aims to get opinions about why solid-state audio amplifier circuits are almost invariably much more complex than valve/tube amplifier circuits. One could think that, if a good tube circuit is just redone, susbtituting each tube by a transistor (common cathode by a common...
  5. A

    5V to 12V High Current Switch

    I am using a MSP430 to switch a high powered LED. MSP430 output pin can source 5ma at 5V. I want to switch a 12V source to a LED that will be driving 5A and it will be switched like a strobe very quickly. I need some help with choosing the right transistor or MOSFET in order to accomplish...

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