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Thread: DynaOhm Polarity?

  1. #1

    Default DynaOhm Polarity?

    Hi all, from all I've looked up, I keep seeing that resistors don't have a +/-, and direction shouldn't matter. However, the DynaOhm 4006-20's are clearly marked in/out (+/-), and the brightness of a connected led is quite different if I flip the resistor. The rumble motor I have won't even turn if I run a 3.7v power source through In --> Out, but it will run if I flip the DynaOhm. Is there something I'm missing here?


  2. #2


    Don't take my word for gospel, but from what I understand about DynaOhm resistors are more than just simple resistors. They increase in resistance as the temperature goes up, and effectively act as a thermal protection cut of switch. I also saw on the datasheet that there was something about negative DC output. Negative DC current is... complicated, but perhaps that is what you get when you run DC through the resistor in reverse?

  3. #3


    Normally resistors are not polarized at all, but I guess the DynaOhms are. I've never used them myself, because I can easily do my own calculations, but I guess for the DynaOhms, it does matter which end you use. Good to know.
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  4. #4


    Thanks guys. I ended up going with calculated standard resistors, I didn't like brightness, or rather the lack thereof, that DynaOhm gave. Just thought it was odd that they clearly had a +/-.

  5. #5


    Pure speculation but there is a trick with diodes where you can hit a ceiling on what voltage they put out. This is often used as a cheap voltage regulator. The Dynaohm might be a combination diode and resistor, that would explain the polarity.

  6. #6
    Owner of the Custom Saber shop Strydur's Avatar
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    Oct 2005


    For a DynaOhm you hook the IN to the positive of the battery and the OUT to the + on the LED. You can see one hooked up in the picture here..
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