Resistors getting hot?

Discussion in 'FAQs' started by tverskaya, Jan 19, 2007.

  1. kf4jqd

    kf4jqd Active Member

    Hold on! If put 2 1000 ohm resistors in paraellel. You will get 500 ohms. So keep them!

  2. Gary S.

    Gary S. Senior Member

    If you just want to play around with some LEDs and resistors to get a feel for them, get a 0 - 5K ohm 1/4 watt potentiometer from the electronics store and put that in series with your resistor. Start off with higher values of resistance, then vary the potentiometer to see what the LED does as for brightness goes. If you can measure the current too, then all the better.

    Be aware that they do make low current draw LEDs that can handle only 2mA instead of the normal 20mA. These need alot higher resistnace in series than the normal ones.
  3. tverskaya

    tverskaya Member

    Andy - Adding and substracting...hadn't thought of that yet.

    Now I think I'm more needing some additional resistance. Using my logic which may or may not apply in semiconductoria, the resistance should double if I were to put two resistors in series.. Two 500 ohm transistors making 1000 ohm, basically.

    Any chance that this might work then?
  4. cidchase

    cidchase Active Member

    Yes, a good chance that will work.
    What value was the resistors they sold you? Or the color code?

    Do you have a meter, VOM, DMM, multimeter, whichever your term may be?

    You can use it to measure the resistor value and the voltage across it, your source voltage, and the curent thru it. You can also check your source voltage with it, so you won't be guessing.

    You will find the meter to be invaluable if you are going to do much more of this kind of thing. It's well worth the investment! I'm not too sure I would go back to that same store for it, though.:D :D
  5. Russ Bellinis

    Russ Bellinis Active Member

    If my understanding of Ohm's law is correct, if you took 4 1000 ohm resistors, and connected them in parralel pairs you get 2 resistors at 500 ohms but double the wattage. Now if you hook two sets in series, you get 1000 ohms with double the wattage. It would be better to use one large resistor than 4 small ones, but if you already have the smaller ones, this will save you from having to just throw what you have away.
  6. tverskaya

    tverskaya Member

    Russ - double the ohmage and halved wattage, right, with the serial option?
  7. Gary S.

    Gary S. Senior Member

    I agree with Russ. If you have four 1000 ohm, 1/8 watt resistors, you could make two parallel groups. These would be the equivalent of 500 ohm 1/4 watt resistors. If you put the two parallel groups in series, this group of four resistors would be the equivalent of a 500 ohm, 1/2 watt resistor.
  8. YmeBP

    YmeBP Member

    Yeah seriously, i've managed to figure out that i have everythign i need to add led's to just about everything i have rolling around my tracks .. welll... except of course the acutal leds... but i'm working on that :). I have a ton of old computer parts, boards cdrom drives etc that i can scavenge for leds. :0

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