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  1. K

    Ft of the transistor

    An hfe = 6 makes for a real low input impedance. Since the collector current is a fraction of the emitter current, the output signal size is less. If your VCE isn't high like the 20V shown in the data sheet, your hfe will be even lower. Also, the more you change the hfe by a high change in...
  2. K

    Microwave Transformer

    That's what it was, an empty metal box with a cover.
  3. K

    current and voltage out of phase

    If your using a power source, like the secondary of a transfomer to run the motor, why do need a start capacitor? The power source has enough power.
  4. K

    120VAC to a2VDC 30A power supply circuit needed

    If the transfomer is center-tapped, you could get +- 12. Then add parallel regulators for as much current as you need. 25A is a lot of DC currrent. Otherwise, they make good variable regualtors with high input voltage and any ouput voltage and good current. Or you could throw in some high...
  5. K

    current and voltage out of phase

    Is there any relevance to this concept? I use reactance for phase calculation, and I can't think of where the current/voltage phase relationship is ever used. I just figured that if I had a capacitor in an AC power application, I could add an inductor somewhere and get more power. Maybe that's...
  6. K

    building a generator

    I think the rotor would have to be of the permanent magnet type. Sometimes it's all electromagnetic, which requires AC power. Let us know if it works.
  7. K

    current and voltage out of phase

    Does current that is out of phase with voltage mean lower available power. I see inductors used everywhere in power supplies, but are they used for more than ripple reduction?
  8. K

    PC Control Board

    You may want to post in the microcontroller section, MP is good at that stuff.
  9. K

    pi filter

    I think maybe you would determine the reactance. Resonance will give you better filtering, supposedly. I had resonance give me 20db/decade one time.
  10. K

    Microwave Transformer

    A voltage clamp. A voltage doubler uses clamping action to get higher voltage,
  11. K

    Microwave Transformer

    I have seen what appears to be part of a clamper on the microwave transformer. But I couldn't find the rest of the circuit. And the magnetron is just an empty box.
  12. K

    alarm circuit using lm555

    I think the circuit should use a PUT. I think SCR's are more often used high current. SCR's are the hard ones to turn off. I wonder why PUT's are not used more in switching applications?
  13. K

    PC Control Board

    I'm not a programmer, but serial communication is still widely used. I think the code is more extensive and the harware more elaborate for parallel port usage. Buffering would be my main concern if using your own computer.
  14. K

    Automobile ignition power transistor

    My car runs great for it's age. It's really too bad though, that people who think their car is in good shape develop major porblems anyway. I really depend on that thing.
  15. K

    Automobile ignition power transistor

    I do tinker with cars a lot. I'll do major work when I have to. About half the time I create a lot of trouble for myself, but it get's fixed. I do anything that is easy, so as to avoid major work.
  16. K

    Automobile ignition power transistor

    Never had a problem. It's just that my car needs any benefit I can give it.
  17. K

    E.C.G. Schematic

    You might want to narrow the problem down. Many things have to go right with that setup.
  18. K

    What is this design for ???

    The USB power probably is not voltage from a regulator, it is switched through a transistor.
  19. K

    Help needed, 3v to 12v circut

    It looks like you want the small relay to power the big relay. Disconnecting the 12V will turn the small relay off, if it's on, and the big relay won't stay on. The pushbutton switch needs to break series, it looks parallel to the load. The hardest part will be saturating the transistor.The...
  20. K

    Help needed, 3v to 12v circut

    I don't understand. Post a schematic so we can see if your circuit has potential.
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