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  1. J

    pwm to control a dc motor

    AFAIK, gain has everything to do with collector current. that is why I stated it had a gain of 40, because this is the min gain available according to the datasheet that is at a collector current that is greater then your load would consume. But the datasheet is always just a best estimate...
  2. J

    Kernel or Off the shelf OS?

    Under the GNU, I believe you would. But that is just one license. Steve pointed out that the BSD license would allow you to do it. You will have to do more research on that subject because I am not very versed in it.
  3. J

    What is this component? What does it do?

    the marking on the board suggest it is a capacitor. Are there any marking on it at all? Others with surface mount experience might be able to tell you more. Looks pretty big compared to the other capacitors on that board.
  4. J

    pwm to control a dc motor

    From the datasheet is says that it will source/sink 100uA - 2mA. You will probably need more then 7.5mA to make sure the transistor goes into saturation. How exactly did you come up with 7.5mA??? The ni9401 will not give you what you want with a 2n2222A. You will need to find a transistor that...
  5. J

    Kernel or Off the shelf OS?

    Well if you already have a kernel, then by all means use it. But a kernel is only as big as you need it. Monolithic kernels like the linux kernel can be stripped down to the bare essentials and then you can build on top of that. It is like peeling an onion. You peel off a layer till you get what...
  6. J

    Why does my camera go flat so fast?

    I had a camera, nikon that would eat batteries. 15 - 20 minutes of constant use and the batteries were dead. So I guess it is conceivable to get one that would only last 10 minutes. I was always taking macro shots with mine, so maybe that had something to do with the power drain.
  7. J

    Kernel or Off the shelf OS?

    I agree with steve, to re-invent the wheel is non-sense when you can just build on top of a preexisting platform while still maintaining property rights of the stuff you create. Not to mention, if in the process you can help make the open source project you are using better, then it is a...
  8. J

    USB + Switch + 5 LEDs

    What is the current rating on those blue led's? If bob is correct then you are pushing 30mA right now. Make sure the LED's can handle 30mA
  9. J

    Heat Generation

    Maybe I am whack, but would it be possible to use PWM to pulse a large voltage to a resistor? Then you could use a temperature sensor and a pic to increase or decrease the PWM output to the resistor controlling the heat. Maybe you could do this with a light bulb? Just me thinking out loud is all.
  10. J

    DC > DC converter problems please help!!

    Here is an example of a typical AA battery. Less then 2 hours with a 1A draw. Notice voltage drops off as the battery discharges. http://208.173.184.182/OEM/Primary/Alkaline/mx1500.asp
  11. J

    DC > DC converter problems please help!!

    You do realize the batteries can not deliver all their power at once right?
  12. J

    DC > DC converter problems please help!!

    What is your output voltage? What is your input voltage? How much current does the converter need to supply on the output? ~42W/13V = 3.23A available on the output. Should probably figure 3A max.
  13. J

    pwm to control a dc motor

    Nope.
  14. J

    pwm to control a dc motor

    Yeah but I don't know why you would want to do that. It involves bringing Vcc down to 3V Because a 100% duty cycle is ON. If you want to run your motor at 100% duty cycle then Vcc needs to be 3V. If you want 1.5V from 3, then you need a 50% duty cycle. Because a 0% duty cycle would be OFF
  15. J

    pwm to control a dc motor

    I would think the easiest way to get 0 to 100% duty cycle would be to use a uC aka, microcontroller with PWM output pins. If you know the frequency of the square wave, then you can find the time period. time period in Seconds = 1/freq 1/1000Hz = 0.001S If you have a pulse of 12V and you...
  16. J

    DC > DC converter problems please help!!

    What is the efficiency of the boost converter? It is probably in the datasheet for the IC. This will give you a very close approximation to what is lost in the circuit. You put in 100W of power and get out 95W of power, then the efficiency of the circuit is 95%.
  17. J

    DC > DC converter problems please help!!

    You can't create power from thin air. You can only convert one quantity of power to another quantity of power, but the overall power won't change from in to out (except for the losses in the circuit.) Power = voltage x current. The answer to your question is yes if you want to make a boost dc...
  18. J

    Help in understanding the math behind the schematic.

    Well this was my original thread. This was one of the first projects I ever took on. The link below is what I ended up with. It uses a flip flop and will sound the alarm for a set time period based on the 4060. Check it out, it is fully functional and easily up-gradable. You could even use...
  19. J

    System for motion sensing and control

    accelerometer? http://www.dimensionengineering.com/accelerometers.htm
  20. J

    LDR Motor Circuit

    proteus isis
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