AnDyMaN

iTrader: (19)

alright, this is a bit of an electronic question so i figured i should ask here.

so im trying to simulate my o2 sensor heaters with some resistors. www.o2simulator.com has instructions in which it states to use 20watt 20ohm resistor for each sensor. so i go out and buy 10w15ohm, 5w2.2ohm, and 5w2.7ohm. adding all together equals 20w20ohm

i hook it up, and after about 10 minutes of driving, i smell something burning. the resisters get so hot it starts melting the electric tape. and not only that, the plastic that is covering the resistors is starting to crumble!!!

now, can anyone tell me what happened?

did i add up the numbers wrong??

i hooked it up like this.

WHITE WIRE - 3 Resistors - white wire

i believe it was wired in parallel......... ???? was that a bad move??

and does anybody know what is the best size resistor to use for this?

and do i need to specially mount the resistors somewhere so it doesn't burn anything?\


thanks for your help guys. im not that good at wiring....

Pearl96Max

iTrader: (151)

Wattage is too low. Adding up is fine, but the wattage must be definate.

AnDyMaN

iTrader: (19)

would wiring in serial be a better idea? as i was thinking more about, i think thats what im supposed to do.... yeah?

also, how much watts do you think i should use? and ohms?

Pearl96Max

iTrader: (151)

No, your wiring is fine, your wattage value is too low. If it calls for 20W, then you need to use 20W resistors.

joecurr

If you wired those resistors in parallel, you will end up with a final load a lot less than 20ohms, probably somewhere between 1-2ohms. That low of a resistance will draw a lot of current, hence the resistors getting extremely hot. If you want to add resistances, you have to wire them in series.

D Love

If you can't find 20Ohm, 20W resistors, do two 10W 40Ohm resistors in parallel (if it's easier to find those). They will split the current between them, so they don't need to be as high in wattage.

Batxel

iTrader: (1)

Your main issue as everyone else said is the wattage. You would need the 20W versions of all the resistors that you have then you connect them in series not parallel. Once there is too much current going through the resistor then it will just burn it self up.

AnDyMaN

iTrader: (19)

so (2) 10w40ohm in series....

is that okay?

D Love

You need them in parallel. That will drop their Equivalent Series Resistance down to 20Ohms. The way you have it, you're getting 80Ohms of resistance.

Pearl96Max

iTrader: (151)

I do stand corrected on my statement of 'your wiring is ok", I didnt read fully and ASSumed you already ran in series..

AnDyMaN

iTrader: (19)

ahhh i c...

so 10w40 ohm in parallel

or

add up the resistors i have (new ones) in series.

right right?

sorry for sounding so repetitious... i messed up like 3 times already, im tired of driving thru traffic just to mess up again.

D Love

Here's the deal. Worst case scenario with a 20W, 20Ohm resistor would be 20V (1A). So, if you had 1A running through your circuit, then you would need resistors with a Watt rating equal to their Resistance rating (P=I^2*R; 1^2=1; P=1*R). i.e. a 5Ohm resistor needs to be 5W. 2.2Ohm -> 2.2W. Follow that rule for series.

If you're going to do parallel, do 2 40Ohm, 10W resistors.