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  1. BobK

    Driving Peltier Device through L298N to control Temperature

    Kris, I am curious as to why not? Certainly at a low frequency (sub 1 Hz) you could use PWM to control the temp, no? Bob
  2. BobK

    brushless motor RPM?

    If the motor is simply sensing the position with a hall sensor and activating the proper windings that way, it will act just like a brushed motor. The speed will be a function of the voltage applied and the load. Bob
  3. BobK

    12v voltage stabilizer?

    A cheap solution: http://www.ebay.com/itm/Auto-DC-DC-Boost-Buck-Converter-Solar-Voltage-Regulator-25W-3-15V-to-0-5-30V-/221264404431?pt=LH_DefaultDomain_0&hash=item338462dfcf Bob
  4. BobK

    Help with a two-way circuit?

    Hi Feenie, and welcome to the forum. I have read your post 3 times and I have no idea what you are talking about. Please try to describe what you are trying to do, assuming we have no knowledge of it. Bob
  5. BobK

    charging a Battery using voltage range of 3 V to 12 V rangle...

    You will need a buck-boost converter to handle the input voltage range. Bob
  6. BobK

    Designing a regulator?

    You would use a voltage regulator. A very common one is the 78xx series. A 7806 will regulate to 6V at up to 1A. However, your wall wart will need to be at least 8V to get 6V out. Bob
  7. BobK

    Transistor Switching: Am I Doing it Right?

    To get the highest switching speeds on a 2N3904 you are going to need a collector resistor in the hundreds of Ohms, not 10K. Bob
  8. BobK

    Signal isolation - optocoupler

    Any opto coupler can be used for a varying output by varying the input current, but I believe some are specifically designed to do that accurately. I have no experience with them though. Bob
  9. BobK

    Sweep Generator and Breadboard Question

    Why not just use a transformer? Bob
  10. BobK

    A myth about Generators and backfeeding

    That is not what the OP is referring to. Backfeeding is simply connecting your generator to your house wiring when the electricity out due to a storm or whatever. Not putting power onto the grid. Bob
  11. BobK

    "Dimming" LED's with pot/rheostat by progressive shutoff

    I was trying to get at his reason for doing it. If it is just to control the amount of light, PWM is a better way. The use of the word "dimming" in the title indicates to me that he is just wanting to control the light output. Bob
  12. BobK

    A myth about Generators and backfeeding

    You MUST disconnect from the incoming power in order to backfeed, i.e. open the main breaker coming in to your panel. Then the two problems above are avoided. Bob
  13. BobK

    Signal isolation - optocoupler

    Are you planning on putting a reverse voltage on the opto input? If not, you are indeed looking at the wrong thing. You drive an opto just like an LED, so you would just calculate the resistor based on the input voltage. Bob
  14. BobK

    Need project help!!!!!

    Sounds like a good microcontroller project. What kind of help are you looking for? Bob
  15. BobK

    Electronic scanner info help please

    Just shrink some scientists and inject them into the bloodstream in a nano-submarine. Bob
  16. BobK

    Constant Current Drive

    1. Yes. 2. Yes. 3. Yes. 4. Most likely dim or not on. Don't do it, though, you would strain the driver. Bob
  17. BobK

    Help with Tiny Monitor Cube Thingy

    Do you really think you can just hook up a memory stick to an LCD and an image will be displayed? Let alone an animated image? Open up an LCD picture frame and look it what is inside. If you think you can build 4 of those to fit in your small rectangular cuboid, then go for it. Bob
  18. BobK

    "Dimming" LED's with pot/rheostat by progressive shutoff

    Is the final purpose to control the amout of light output, or do you really want the effect of having some % of LEDs on depending on the position of the pot? Bob
  19. BobK

    Looking for easy Breadboard projects

    A relaxation oscillator is about the easiest understood circuit that actually does something on its own. Using a UJT it is quite simple, though they are not in common use these days. I would blink an LED with it. Here is a circuit: http://www.electroschematics.com/4852/mock-flasher-led/...
  20. BobK

    Op amp calculations for ramps!

    As long as the ratios are the same and the inputs are driven a low impedance source, compared to the input resistor, the results would be the same. Bob
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