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  1. BobK

    PCB manufacturing

    There are tons of them. Try google. Or, I used ExpressPCB, which gives you 3 boards for about $60. Bob
  2. BobK

    multifunction/colour LED array on batteries, possible?

    A microcontroller is a single chip programmable computer. The control box on the link GreenGiant pointed to most likely has a microcontroller in it. Bob
  3. BobK

    Combining a radar detector and smartphone with 1 set of headphones.

    You can connect two audio outputs together by putting connecting the grounds together and putting each signal through a resistor and finally the two resistors to the headphones. I would start with 33 Ohms and if the volume is not sufficient go down to 15 Ohms or 10 Ohms. Bob
  4. BobK

    multifunction/colour LED array on batteries, possible?

    If you can build your own PCB, then making a microcontroller circuit to fit in a 25mm tuibe would not be a problem. You don't say how many LEDs your are talking about, that might be a factor. Bob
  5. BobK

    Modifying fluctuating DC voltage

    Too bad, the circuit would be far simpler and more flexible if you did use a microcontroller. Bob
  6. BobK

    Looking for a schematic symbol for adjustable mechanical thermostat?

    As far as the circuit is concerned it is just a switch. Use that symbol and label it approriately. Bob
  7. BobK

    Electricity Flowing (how quick)

    The signal travels at the speed of light, not at the speed the electons move, so your statement that you can move data faster by using more voltage or current is incorrect. Look at at it this way: Fill up a tube with marbles. Now push a marble into one side of the tube. A different marble...
  8. BobK

    DC > DC converter problems please help!!

    Normal Alkaline batteries that you buy at the drug store will have at least 12000mAH and be much cheaper. This is only to test what the motor draws at 12V. You don't need anything special. Bob
  9. BobK

    Calculate frequency using MCU

    If you are sampling at at least 10X the frequency you can get the frequency and amplitude from the samples, no need to determine the amplitude separately. Bob
  10. BobK

    DC > DC converter problems please help!!

    A battery made from 8 D cells would be sufficient. Bob
  11. BobK

    Modifying fluctuating DC voltage

    What device are you putting the output to? -0.1 to 5V seems like a very strange range. Bob
  12. BobK

    DC > DC converter problems please help!!

    Here is how I would proceed: First, get a new DC-DC converter board, the one you have is most likely damaged. Use a 12V bench supply that can supply plenty of current and measure the current drawn by the motor at 12V. Is this withing the range of output currents your DC-DC converter can...
  13. BobK

    DC > DC converter problems please help!!

    Moha, If you come here for advice, it helps if you listen to it. Steve is very knowlegable. What he is telling you is entirely correct and you simply ignore him. If you don't understand, ask for clarification. If you insist on arguing with people who know way more than you do, you might...
  14. BobK

    LCD screen programming

    The block diagram in the datasheet for the LCD module indicates that it is, and the connections that are brough out are exactly the inputs to the controller chip, so it seems to me it is. If you has a "bare glass" LCD it would require hundreds of connections to make it work. Bob
  15. BobK

    LCD screen programming

    I think the controller chip is integrated into the display module. If you look at the block diagram, the interface to it seems to be an 8-bit parallel data interface. You need to get a datasheet on the controller chip in order to find out how to talk to it. A microcontroller will be required...
  16. BobK

    Question about ac adapters

    Never mind.
  17. BobK

    DIY retracting License plate help.

    That would work, if what you want is a remote control for the motor. I did not get that from your original post. Bob
  18. BobK

    DC > DC converter problems please help!!

    1. You are very confused about current (Amps) and battery capacity (Amp Hours.) They are two different things. 2. When you put batteries in series the current and the capacity do not increase. I.e. 4 batteries with 2500mAH capacity in series still has 2500mAH. 4 batteries that can supply...
  19. BobK

    Batteries in Series

    There is no insulator between the two terminals, you show a wire there. The voltages add because that is what they do. If the voltage between A and B is V1 and the voltage between B and C is V2 the voltage between A and C is V1 + V2. The voltage across a wire (ideally) is 0. Bob
  20. BobK

    LDR Motor Circuit

    A modern rail-to-rail opamp would be a big improvement over the obsolete '741 you are using. Bob
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