Resistor Advice

kevinkhan · Feb 7, 2010

Im looking to buy a resister for a faulty circuit board i have.

The one i have high lighted in this photo is the one im looking for
**broken link removed**

I have tryed Mouser and Digikey buy neither of these site sell this resistor..

How would i go about putting two resisters together to make up this resistor and can some one tell me what the ohm rating is for this component..

Is there a way of connecting two 10watt resisters together to make up this and do i connect them in parallel or serious..

Thanks and hope some one can help..

audioguru · Feb 7, 2010

You need 3.9 ohms 5% at 20W.
But nobody makes two 1.95 ohms 5% 10W resistors for you to connect in series and nobody makes two 7.8 ohms 5% 10W resistors for you to connect in parallel.

killivolt · Feb 7, 2010

kevinkhan said:
Im looking to buy a resister for a faulty circuit board i have.

The one i have high lighted in this photo is the one im looking for
**broken link removed**

Thanks and hope some one can help..

Does this look familiar ?

diyAudio

3.9 ohm and it might be difficult to find something around 10w and 2ohm to wire in series.

You might try an Old Television they use those. Maybe even old monitors.

That would be as close as you could get. They would just burn up anyways.

killivolt · Feb 7, 2010

audioguru said:
You need 3.9 ohms 5% at 20W.
But nobody makes two 1.95 ohms 5% 10W resistors for you to connect in series and nobody makes two 7.8 ohms 5% 10W resistors for you to connect in parallel.

Mr. Mcquaky.

Sheesh, I would have known I couldn't beat you.

kevinkhan · Feb 7, 2010

So its impossible to connect 2 resistors together to make a 3.9ohm resistor.. Is there anyway of connecting 3 or 4 together?

vne147 · Feb 7, 2010

3.9 Ohm, 20W, 5% Sand Stone Resistor

Hero999 · Feb 7, 2010

You could use two 8R2 10W resistors or four 12R 5W resistors in parallel.

EDIT:
Another option is to use a network of two 5W 3R9 resistors in series connected in parallel (four in total), I'll post a schematic if I've not made myself clear enough.

kevinkhan · Feb 8, 2010

vne147 said:
3.9 Ohm, 20W, 5% Sand Stone Resistor

Thats brilliant lets hope they ship too ireland..

You could use two 8R2 10W resistors or four 12R 5W resistors in parallel.

I worked out what resistance it would be to connect two 8.2 ohm resistors in parallel and it came too 4.1 ohm
would there be any great difference if i used a 4.1 ohm instead of a 3.9 ohm?

Thanks for your help guys

meatpie · Feb 8, 2010

RS Components in Ireland

Click here **broken link removed**

Just cut off the mounting pods with a hack saw and sit them on the board with a blob of sylastic. I've used hundreds of these, they're the bee knees.

Should be free post when you order on-line, it is in Aust.

vne147 · Feb 8, 2010

kevinkhan said:
Thats brilliant lets hope they ship too ireland..

You could use two 8R2 10W resistors or four 12R 5W resistors in parallel.

I worked out what resistance it would be to connect two 8.2 ohm resistors in parallel and it came too 4.1 ohm
would there be any great difference if i used a 4.1 ohm instead of a 3.9 ohm?

Thanks for your help guys

The 3.9Ω resistor has a ±5% tolerance. So, worst case its value could be as high as:

3.9 + (3.9*.05) = 4.095Ω ≈ 4.1Ω.

I'd say it is OK but without seeing a schematic it's hard to say for sure.

meatpie said:
they're the bee knees

LOL, I love it!

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