Search results

Search Forums New Posts
  1. BobK

    Looking for somebody to create my project

    Sounds simple doesn't it? Well... You haven't specified it very well, so it is hard to tell. When you say "turn on at different times" do you mean different times of day? If so, it has to be a clock. If not, time from when? Then it needs some way of telling you when setting the on...
  2. BobK

    Newby Electronics Question....

    I can't even imagine where you got a 10000 Megohm resistor, but if you really are using resistors that high, I can see a lot of problems. How is the circuit constructed? There is likely to be leakage that overwhelms a 10000 M resistor all over the place. I would think you would need special...
  3. BobK

    Help in desiging an electric motor!

    If you want a motor that is strong an operates on low power, it is unlikely you will be able to build one that would outperform what you would get commercially, or that you could build it for lower cost. Bob
  4. BobK

    Whats a good but simple program to draw circuits on my pc?

    Here is an example of a schematic and simulation of a circuit near and dear to your heart. The voltage shown is at the anode of the LED. Bob
  5. BobK

    Whats a good but simple program to draw circuits on my pc?

    LTSPICE has a schematic capture program this is easier to use than any of the others I have tried. Plus it is free, and you get the advantage of being able to simulate the circuit! http://www.linear.com/designtools/software/#LTspice Bob
  6. BobK

    Digital Pot setup

    The voltage divider consists of 2 resistors, one from V+ to the the PICAXE input, and the other from the PICAXE input to ground. By on the lower leg, I mean across the resistor going to ground. This will be the smaller resistor. 1K and 2K would work, but I would use more like 10K and 20K...
  7. BobK

    Digital Pot setup

    You use a 2:1 divider, which gives you 1/3 the battery voltage on the lower leg. This is what you feed into the micro. The micro converts this voltage into a digital number in the range of 0..1023 with 1024 meaning 5V. So When the battery is at 12V you will get 4 volts at the divider and your...
  8. BobK

    Voltage multiplier circuit required

    The big problem with the 0.5V is that you cannot operate transistor switches from this voltage. So I think Steve had the right idea. You need a low power source just to get the control voltage to operate MOSFETs. A Joule Thief might actually work for that part, or you could even use a...
  9. BobK

    how to turn on LED using 1 square wave

    What do you expect to happen when the third pulse comes? Bob
  10. BobK

    difference between............

    Just don't run the constant current supply with no load, it will output infinite voltage :)
  11. BobK

    Newby Electronics Question....

    10000 Meg? Bob
  12. BobK

    optical punch card reader

    The base is connected to the light coming in! Bob
  13. BobK

    Voltage multiplier circuit required

    What you need is a Joule Thief on steroids. Bob
  14. BobK

    Amplitude Modulation using Op Amp.

    Interesting, you are indeed right, they all seem to use a jfet as a voltage controlled resistor. I know I have found some discrete transistor cicuits based on a differential amp state, but I can't seem to find one now, and none using op amps only either. Bob
  15. BobK

    Gear help

    Damn, I really regret getting my bachelor's in physics. Just think of what I might have done! Bob
  16. BobK

    Gear help

    :rolleyes: Bob
  17. BobK

    Voltage multiplier circuit required

    Not to mention that you are unlikely to get high efficiency at 0.5V input. Bob
  18. BobK

    Amplitude Modulation using Op Amp.

    Let me google that for you: http://www.lmgtfy.com/?q=op+amp+amplitude+modulation Bob
  19. BobK

    Gear help

    He wants to push 2 pistons approximately 55cm at 33000 strokes per second, pumping air, with a small, low powered motor and gears and light in weight! Seeing as the speed of the piston is 33600 m/sec or about 100 X the speed of sound in air, think we can unequivocally state he is trying to do...
  20. BobK

    Project Help!!

    This one uses 4uA: http://www.linear.com/product/LTC1541 Bob
View older results
Top