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  1. BobK

    Transistor Base Resistor, how to calculate

    Resqueline, Oh no, I did it again. :)
  2. BobK

    Schematic to reality conversion

    Why do you say 1/8 Watt? The '386 can put out as much as1 Watt, and this circuit is designed to drive the amp to clipping. I think an 1/8 watt speaker is asking for trouble. Bob
  3. BobK

    Transistor Base Resistor, how to calculate

    How much current is the fan drawing? The transistor you point to can only handle 100ma, which sounds low to me. Bob
  4. BobK

    Need vericifacation that this will work

    All of your logic could be easily replaced by a single microcontroller chip, but if you are not familiar with them it is a steep learning curve, particularly if you have no programming experience. Bob
  5. BobK

    Need vericifacation that this will work

    Does the word "microcontroller" have any meaning to you? Bob
  6. BobK

    Resistor Question

    If you parallel LEDs, each must have it's own resistor. bob
  7. BobK

    DIY PCB

    Yeah, it is not that good. If you already know eagle, and it can output protel, why not try using it? The problem is you will have to name the package for each part you use to conform with what veeCAD wants. Bob
  8. BobK

    High Power DC Electromagnet

    One more thing w-e-w, As you can see, wel all think EMF are not dangerous to people or other animals and plants. But I happen to know that strong mangetic fields are DEADLY to ghosts, none has ever survived even a minimal exposure. So please be very careful! Bob
  9. BobK

    High Power DC Electromagnet

    I believe it was Sharper Image or Brookstone who actually sold (maybe they still do) a device that produced ozone and directed it under you nose to sterilize the air you breath. Unbelievable what New Agers (haven't been hippies for about 40 years) would buy. Bob
  10. BobK

    High Power DC Electromagnet

    A nitpick: You can increase power by charging a capacitor and then releasing all the energy more quickly than the battery can. What you cannot increase is energy. (power = envery / time) Bob
  11. BobK

    High Power DC Electromagnet

    wide_eyed_wizzard, And MRI will expose you to magnetic fields that you will never achieve with anything you build. I have had several and I am not dead yet. Bob
  12. BobK

    IC 555

    Just to confuse you a little more, no, it depends on how the LED is wired. If the LED is wired between the output and ground, and output HIGH will turn the LED on. If the LED is wired beteen the output and + supply, output LOW will turn the LED on. This is possible becuase the 555 has a...
  13. BobK

    Simple transmitter-receiver

    You would be much better off to buy off-the-shelf modules. They are really cheap, can be had for <$10. Bob
  14. BobK

    DIY PCB

    I am at work now, but I think I remember that it need protel format for the netlist. Any schematic capture that can produce that format should work. As far as autorouting goes, I agree with Steve. There is a for-purchase version of veeCAD that has it, but I would not bother. My experience...
  15. BobK

    Boost converter

    Actually, I don't think that chip is good for using an external MOSFET. A high power MOSFET needs a push-pull driver so that it can both charge and discharge the gate capacitance quickly. You might want ot look for other boost converter controllers that are designed for an external MOSFET...
  16. BobK

    DIY PCB

    The empty space is my fault. The layout is not automatic it is manual, and I did not try to go for a high density since I had plenty of space on the board for the circuits I was doing. Bob
  17. BobK

    DIY PCB

    Here is how it works. 1. You create a schematic. They reccommend TinyCad, which is another free tool, which I used. 2. You export a netlist from TinyCad or another package and you import it veeCAD. 3. In veeCAD you need to make up packages for each of the parts which give the...
  18. BobK

    DIY PCB

    There is transparency film for ink. http://www.staples.com/Apollo-Quick-Dry-Inkjet-Printer-Transparency-Film/product_449766 Bob
  19. BobK

    DIY PCB

    Have you tried VeeCAD? It is like a PCB layout program for stripboard. I used it for these two boards and had only one mistake (easily fixed missed cut) between the two of them. The top board is uC based constant current LED driver. The second is a low power audio amp (I just had to do my...
  20. BobK

    about simulation software

    LTSPICE does everything I need for free, and has the easiest schematic capture I have seen. Bob
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