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  1. BobK

    Does Your Wiring-Soldering Look Like This?

    I like the enclosure made of copper-clad boards soldered together. For some reason, I have never thought of doing it that way. Bob
  2. BobK

    How do I build a Metal Detector?

    10 MH chokes are hard to come by. Bob
  3. BobK

    Transformer Voltage Amplifier

    I would use the 0 to 3.7 V as input to a PWM controller running at 12V. You can find PWM controllers that are controlled by voltage. An op amp could adjust the range. I.e. if you had a PWM controller that takes a 0 to 10V input, you would use an opamp with a gain of 2.7 to transform your...
  4. BobK

    Do a variable AC, high-amp power supply exists?

    I hope you have lot's of money. Bob
  5. BobK

    Photo-resist PCB help

    Yes, it seems to me that with positive art, a gap would undercut the traces since light would creep in from the sides rather than widen them, this is why I did not think that was the problem. I did brush with a foam brush that came with the exposure kit during development, but perhaps I was not...
  6. BobK

    Photo-resist PCB help

    The toner was against the PCB. I know this since the image is mirrored as it should be. Bob
  7. BobK

    Photo-resist PCB help

    Pre-sensitized. MG Chemicals brand, not suspect Chinese stuff. Bob
  8. BobK

    LED 1.5Vfd???

    Blue LEDs typically have a Vfd of 3.3 to 3.6V. But that does not explain your problem. Bob
  9. BobK

    Photo-resist PCB help

    It was positive. The image on the left is exactly what was printed onto the transparency. If find it hard to think of any mechanism to widen the traces, it seems like most mistakes would do the opposite. The thing I can think of is underdevelopment, where not all of the resist was taken...
  10. BobK

    Photo-resist PCB help

    I have just tried my first attempt at a photo-resist PCB. The results, shown here are not quite ideal. All of the traces should be the same size at 0.12 in. Obviously some of them have bled out to the point where clearances are not met, while others look quite sharp. The image on the left is...
  11. BobK

    Are PICs still being used

    I don't understand this. As far as I know, all PICs can be programmed by the PICKIT 2. Not all are capable of using the real-time debugger, and not all can be programmed from MPLAB, but the stand alone app will program all of them. Can you tell us what PICs were not compatible? Bob
  12. BobK

    Analog input to USB output for LabView use (medical)

    You could build this with a microcontroller that has A/D and a USB interface. You might need an opamp or two to condition the signals. Bob
  13. BobK

    GPIB to USB

    Okay. It helps to tell us what you have done to resolve a problem instead of just asking for help. If you had done that I would not have made my snide remark. USB -> GPIB makes sense. I am not sure the reverse does. What kind of USB devices to expect your GPIB device to control? Bob
  14. BobK

    do I required a pre amp

    Yes, you cannot simply wire different outputs together since both are trying to put out some voltage. Put a resistor between each output and the input. 1K would be a good value to try. Bob
  15. BobK

    GPIB to USB

    There is this nifty tool, called "Google" that can find things like that. You should try it. Bob
  16. BobK

    harmonics and fundamental frequency

    Harald, Not sure why this comment is directed at me? Bob
  17. BobK

    (Woo Woo) Efficient HHO Cell

    You should read up on yydrogen powered cars. The biggest problem is storing enough fuel since it only liquefies at very low temp or high pressure. This is why the HHO people produce the gas from water in the car, the water can be stored easily and safely. Bob
  18. BobK

    Simultaneous events

    The 18F45K50 is an update of the 4550 that has more features and costs $2.93 unit price from Microchip Direct in PDIP or $2.74 in TQFP (surface mount) Bob
  19. BobK

    harmonics and fundamental frequency

    This reminds me of a realization I had recently. I remember studying how early astronomers used epicycles, i.e. smaller cycles in an orbit that could match the orbits better than a circle. I thought at the time that that seemed ridiculous. But recently I realized that they had basically...
  20. BobK

    circuit design

    Well, I do try to balance my PC boards with the weight / shape of components to give an good aesthetic result. I even consult my wife, who majored in art. Had not really thought about color much though. Bob
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