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  1. BobK

    Project Help!!

    This one costs 14 cents for two in a package: http://www.onsemi.com/pub_link/Collateral/LM393-D.PDF Bob
  2. BobK

    Crashing after 145 seconds

    Most compilers don't have instructions that would time out. I can see someone putting a clear in a delay function, but that would not be the compiler doing it. I don't use basic, but I suspect this PAUSE instruction is a delay, which would be a function call in C. Bob
  3. BobK

    Project Help!!

    Trying to figure out why you would not want to use a comparator IC. Bob
  4. BobK

    Crashing after 145 seconds

    The watchdog timer does not run off the system clock, it runs of the 31KHz low frequency oscillator. And contrary to what CocaCola said, the C compiler does not insert watchdog timer resets. And if it did, it would render the watchdog timer useless. Bob
  5. BobK

    Gear help

    Why do you think you want to spin something at 2M revolutions per minute? Bob
  6. BobK

    How do I find the right transistor?

    Look up energy harvesting. Others are way ahead of you. Bob
  7. BobK

    Plz help me

    How much current did you draw for how long before it died? Bob
  8. BobK

    12V / 6A Power supply. Help with Buck and Boost converters + OR'ing circuit

    If you are expecting to get 6A at 12V from two 4AHour 3.7V lithium batteries, do you realize that they will need to put out over 10A and last about 24 minutes? Also, what is the maximum discharge rate for the batteries? I expect you are exceeding it. Bob
  9. BobK

    How do I find the right transistor?

    What is this large source of energy you want to tap in the region of 0.2V? Do you realize that in order to get signficant power at these voltages you will need large currents (eg. 5A to get 1Watt.) I think you are chasing a wild goose. Bob
  10. BobK

    3.5mm Headphone Jack LED?

    If your calculation is right, there is no hope. .24V at 10uA = 2.4uW Typical red LED 2.0V at 20ma = 40000uW = 40mW But I think it is wrong. A typcial headphone amplifier puts out about 50 to 100mW, which is enought to light even the ineffiecient LED above. Bob
  11. BobK

    ele Math

    What is the difference between putting them in parallel and connecting each of them to the battery? Youi won't get much light out of an LED with a forward voltage of 3.5V by applying 3.2V to it. Bob
  12. BobK

    step dependant indicator lights circuit question

    Like this:
  13. BobK

    Digital Pot setup

    The ADC works from a reference voltage. By default this is Vdd, but I can be input on a pin. To make it's range 0 to 4.12V you would have to provide a 4.12V reference. Bob
  14. BobK

    3.5mm Headphone Jack LED?

    The second method is a lot better. I doubt that there is enough power in coming out of the headphone jack to directly power the LED. Bob
  15. BobK

    Newbie questions

    You questions about what happens to voltage when devices are in series it looking at it the wrong way. The definition of things in series is that the current thorugh them must be the same. How the voltage divides is complex and can change with time, but, at anyt time, the current through each...
  16. BobK

    controlling lights

    Both are second order filters. The Sallen Key filters would be easier to adjust parameters like center frequency and Q. Bob
  17. BobK

    Wirewound Resistor - Can it be used with 9 V battery ??

    24K is an unlikely value for a wirewound resistor. Bob
  18. BobK

    PIC help

    Your PIC does not support USB communication. The easy way to do it is to get a USB to serial adaptor and use RS232 serial communication, which your PIC does support. You can find such adaptors that will use 0 and 5V signalling which makes interfacing with a PIC easier, no need for an RS233...
  19. BobK

    plz help

    Plz send me $1,000,000 cash. Bob
  20. BobK

    design and impliment class c radio frequency power amplifier

    When I need to design something that I have no idea about, I usually start by reading about it so that I do have some idea. Hope this helps. Bob
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