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  1. BobK

    Can someone confirm the gain here please.

    That looks like negative feedback to me and a gain of 1. Bob
  2. BobK

    Magnet coil help (turns, gauge, for coilgun)

    And by the way, I was not joking about the 880 lb of recoil thrust, that was calculated via basic physics. If this is to be a hand-held weapon, I hope it is our enemies who get it first :) Bob
  3. BobK

    What is going on.

    Agree, I have never seen an astable being called a flip-flop before. Bob
  4. BobK

    Heat Pads for Animal Hospital

    MOSFETs are not evil. And if they are, it is only when you have high switching frequencies, which is not the case here. Bob
  5. BobK

    Magnet coil help (turns, gauge, for coilgun)

    There may be a good reason why no one has ever tried it. Bob
  6. BobK

    Magnet coil help (turns, gauge, for coilgun)

    If it were not the fact that this would be impossbile, for too many reasons to list, you would have a rocket engine producing 880 lbs of thrust. Have fun. Bob
  7. BobK

    Heat Pads for Animal Hospital

    Why use a 6A transistor to switch 200ma? I would use a MOSFET rated at about 500ma and switch the + and - on the comparator so that another inverter is uncessary. Bob
  8. BobK

    Magnet coil help (turns, gauge, for coilgun)

    So how many shots per second are expecting to do? Hopefully not 2000. Bob
  9. BobK

    Magnet coil help (turns, gauge, for coilgun)

    Why 2000 pulses per second? A coil gun would typically have 1 pulse per shot fired on each coil. Bob
  10. BobK

    Man-over-board alarmsystem

    I wouldn't worry about sleeping your uController when the receiver is drawing 12ma. Bob
  11. BobK

    Man-over-board alarmsystem

    Despite what others have told you, these modules do need something like a microcontroller. There are basiscally a wireless data link that sends serial data, not an analog transmitter that can be used to send different frequency tones. Bob
  12. BobK

    eBay Arduino Uno Clones

    If you are really cost sensitive, wire up your own boards, it is not all that difficult. When you buy an Arduino you are paying $25 for a $2 chip. Bob
  13. BobK

    3x4 keypad and lcd interfacing with 8051

    Hi, I want $1,000,000. Please give me your email and I will send instructions on where to send it. Bob
  14. BobK

    UK Simple circuit, can anyone make it for me?

    Nope, C.C. means what he says: http://www.sears.com/cajun-injector-30qt-lp-turkey-fryer-w/p-07115964000P?prdNo=1&blockNo=1&blockType=G1 Bob
  15. BobK

    Vintage stereo receiver re-lamp with LEDs

    No, you can add another diode in series. Just subtact another 0.6V when calculating the resistor. A typical LED has a reverse voltage limit of 5V so, with the forward voltage less than that, it is fully protected by another LED anti-parallel, but you can add extra safety if you want. Bob
  16. BobK

    Vintage stereo receiver re-lamp with LEDs

    Yep, that circuit will work. No blocking diode necessary. As steve said, each LED conducts on half the cycle and it protects the other LED from seeing too high a reverse voltage. Bob
  17. BobK

    Battery comparison for emergency light

    Yes, surely the people at Battery University know less about it than you do... Did you read the paragraph above the one you quoted? They can be trickle charged at 0.05C. If you allow about 50% overcapacity, you could recharge at 0.05C in 18 hours. Bob
  18. BobK

    Simple Infrared LED Switch Help

    Then just replace the transistor with the 2N2222 and make the base resistor 1K. This would provide a base current of about 3.5 ma which should be enough to saturate the transistor. Connect LEDs + resistors to the collector and the then to the positive supply. No relay needed. Bob
  19. BobK

    Vintage stereo receiver re-lamp with LEDs

    If the bulb was driven by AC you can wire your two LEDs back to back with a single resistor. Bob
  20. BobK

    Battery comparison for emergency light

    I suspect that they do not make LI Ion batteries in those sizes because people would plug them into devices that want 1.5V batteries. Bob
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