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Dumb Question... — Parallax Forums

Dumb Question...

roughwireroughwire Posts: 78
edited 2007-02-06 21:11 in General Discussion
I've had a brief brain fart. I've forgotten... I've got to wire up about 7 LEDs. Can I or can I not just connect the LED's same leads to each other and just drive the current to them like it's just one LED or is it not possible to wire them parrallel?
P.S. I'm using 9v, I should use a 220 ohm resistor right?

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MIKE

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-02-06 21:07
    You really want to give each LED their own resistor. 9V - 1.7V = 7.3V. If you want 20ma each ... that's a 380 ohm resistor (roughly). You're better using a series/parallel arrangement. 3 LEDs in series = about 5V drop. 9V - 5V = 4V. At 20ma, that's 220 ohms. This assumes you're driving them directly (unswitched) or switched by a saturated transistor (maybe an additional 0.2-0.3V drop).
  • tommytommy Posts: 84
    edited 2007-02-06 21:11
    and there are more comments (from three weeks ago)...



    . here··· http://forums.parallax.com/showthread.php?p=625452


    tommy
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