where to get 0.1 ohm 2W 0.1% resistors?

[lgreen]

Anyone know a link where can I get the 2W 0.1% 0.1 ohm resistors that are used for a parallel chipamp (BrainGT LM4780 boards)?

I'd rather pay more for .1% than try to build a circuit and match up 1% ones; also I know that you could parallel a bunch up to bring the precision up but my question is really where to get the exact part. Have checked digikey and mouser but spent so much time there without finding them (actually did see some super expensive caddock's that were 25W and to-220), i'd thought i'd ask here.

 

[Bazukaz]

Hi,
Do you really need 0,1% ? If it is for output paralelling resistors , i really don't think this would make any sense. The trace/solder resistance would probably be large enough to make the precision by far worse.

Regards,
Lukas.

 

[Mad_K]

I agree with Lukas. 0,1% is simply absurd. 1% is more than good enough (usually they are much closer when taken from the same batch)

 

[lgreen]

I agree with Lukas. 0,1% is simply absurd. 1% is more than good enough (usually they are much closer when taken from the same batch)

I thought the everyone was saying .1% here? Guess not, ok, that makes it easier.

 

[jacco vermeulen]

What a shame.

 

[cliffforrest]

What a shame.

Nice! But that spec requires the 4 terminals - not relevant here!

 

[RDV]

I used 1% for mine and it works fine.

HTH

RDV

 

[DIAR]

If I need a matched pair I buy a bunch of 1% resistors, measure them and choose a pair with same resistance.

 

[tiltedhalo]

.1% 2 to 3 watt resistors?

1% resistors are perfectly fine for parelleling.
Look at the math the 22K feed back resistor is a .1% unit 22000 - .1%=22 or a differance from 21978 to 22022 ohms.
1% 3watt resistor used for you outputs, 1.0 ohm-1%=.01ohms a differance of .99 ohms to 1.01 ohms see where I am going with this

 

[peranders]

The needed tolerance level is less than 10%

If you are going to paralleling 0.1 ohms is rather little if you don't have a DC servo of otherwise trim the output offset voltage.

 

[lgreen]

Yep, I am starting to get it. I may try it with 0.1 ohms and measure the V across each R to see how much "sharing" is happening, if its out of wack, i'll up to .2 or .3.

 

[elementx]

ebay! I just bought like forty .1ohm 4W resitors 15 cents a piece, plus a few bucks for shipping.. here they are...


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4664&item=7593556714

 

[lgreen]

10%

Those are 10% tolerance. I used 1% and .1 ohm 3 watts, seems to be working ok, very low DC offset, but I have measurements yet to complete... Sometimes the leads on these get a little big and don't fit nicely into the pcb.... not sure if you will have that problem with 4W resistors.

 

[-_nando-_]

BPA datasheet says the same thing, but I'm using 5% without any problems hahahaha

The others that datasheet says that must be 0,1%, I'm using 1% ! No problems at all...