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digital pot pnp — Parallax Forums

digital pot pnp

pltmkpltmk Posts: 6
edited 2006-05-26 21:26 in BASIC Stamp
Hi·in the " whats a micro controller" book it shows how to control· current with a digitaL pot and an·npn· how could i do the same thing with a pnp? could i use the same digital pot?

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-05-26 21:26
    In theory you could...Just remember the PNP will work the opposite of the NPN in that it will be a LOW going voltage that will turn on the PNP.· LOW in relation to its·emitter voltage.· If the base is at the same voltage as the emitter the transistor is OFF.· As the emitter voltage decreases in relation the transistor turns on.· Although transistors are current driven as switches it makes more sense to think of thehigh or low voltage turning it on.· But before I confuse you try reading this link.

    http://www.kpsec.freeuk.com/trancirc.htm

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com


    Post Edited (Chris Savage (Parallax)) : 5/26/2006 10:05:28 PM GMT
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