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  1. BobK

    Driving LEDs from 12V

    I would suggest using two strings and two current sources based on LM317, each providing 350mA. Are you sure the forward voltage for 4 add up to less then 12V? What color are the LEDs? And what are their specs? Bob
  2. BobK

    new project random number generator with memory

    This is a fairly simple project for someone who knows microcontrollers well. If you do not know anything about microcontrollers and programming, it is a lot to learn. Bob
  3. BobK

    Volts but no amps from a (small) solar panel

    It cannot show a voltage when shorted. Are you sure you are using your meter correctly? Did you disconnect it from the battery when you measured the current? Bob
  4. BobK

    What is this component?

    Don't you guys get it. This is a super high tech transmitter disguised to look like a harmless broken piece of a PC board. Although it is a little curious these super-spies would have included a feature that would give it away... Bob
  5. BobK

    Resonance

    But at least he is amusing some of us. So now it seems that he wants to determine the force applied by electromagnetic waves on stone, glass and plastic cd covers. I guess someone has to do it. Bob
  6. BobK

    new project random number generator with memory

    Is this homework, or do you actaully have a use for this? Bob
  7. BobK

    Please Help with digital lock

    Welcome to the forum! A single microcontroller chip would replace all of that logic and could be programmed to be more flexible. Bob
  8. BobK

    Sleeping mask

    The video you linked is about startling people with barking dog sounds through headphones. How does that tell me how to build a lucid dreaming mask? Bob
  9. BobK

    Guitar static modulation morse transmitter--will my amp blow up?

    Most likely the guitar pickup is much higher impedance than a speaker, so it will not blow up your amp. If you play music through the amp, outputting it to the guitar pickup, at high enough volume, it should make your strings vibrate. But there is no RF involved, so no, it will not transmit...
  10. BobK

    Humidity Sensor Problem

    Some Pics have a charge time measurement unit peripheral for doing capactive touch buttons. This might prove useful. Here is an app note that tells you how to use the CTMU to measure capacitance: http://ww1.microchip.com/downloads/en/AppNotes/CTMU%2001375a.pdf Bob
  11. BobK

    stepper motor control

    A 16F88 should be able to handle it. Bob
  12. BobK

    what is the best simple free pcb software ??

    I use the free software from ExpressPCB for my DIY boards. I found it to be very easy to use. Bob
  13. BobK

    Controlling a Sony Playstation PS3 (game addiction help)

    If he is truly an addict, he will find a way to defeat it. A relay would be particularly easy to defeat. Bob
  14. BobK

    Split Voltage

    The Raspberry PI can be powered by any 5V USB plug charger. You can get these for a couple of bucks. And are you sure you need that monitor board? The Raspberry Pi has hdmi video built in. Bob
  15. BobK

    what is the best simple free pcb software ??

    Are you going to make the board yourself? Bob
  16. BobK

    HELP with normally open circuit

    Yep. As long as the 12V supply is on, no power will be drawn from the battery because the diode is reverse biased (cathode at higher voltage than anode). When the 12V disappers, the current starts flowing from the battery within nanoseconds. Bob
  17. BobK

    Theoretically. What if? C-EMF > EMF?

    Another way to look at it. Take a simple permanent magnet DC motor. If there was no back EMF, the only thing limiting the current would be the resistance of the windings. So the motor would always draw the stall current, which is way more than the operating current. Back EMF is your...
  18. BobK

    Theoretically. What if? C-EMF > EMF?

    I am sorry if I am wrong about the free energy device. But you seem to be insisting that somehow back EMF is something to be overcome and you will get better results if you can eliminate it. It is not. Is is a fact of life that enters into the operation of motors and generators, it not...
  19. BobK

    Theoretically. What if? C-EMF > EMF?

    Your are going to force current the wrong way through your power source. Why don't you just admit that you are trying to create a free energy device? It cannot be done. Period. Bob
  20. BobK

    HELP with normally open circuit

    You can also just use diodes if you can arrange for the wall wart supply to be a little higher than the battery voltage. Just use a diode from each supply with the anode to the battery / supply + and the cathodes connected together to the power in of your board. That way, only the higher...
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