where to get 0.1 ohm 2W 0.1% resistors?

lgreen · 24th May 2006, 06:24 PM

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 · 24th May 2006, 06:54 PM

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 · 24th May 2006, 08:04 PM

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 · 24th May 2006, 08:15 PM

Quote:

Originally posted by 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)

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

jacco vermeulen · 24th May 2006, 08:16 PM

What a shame.

cliffforrest · 24th May 2006, 10:22 PM

Quote:

Originally posted by jacco vermeulen
What a shame.

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

RDV · 24th May 2006, 10:30 PM

I used 1% for mine and it works fine.

HTH

RDV

DIAR · 24th May 2006, 11:09 PM

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

tiltedhalo · 25th May 2006, 01:43 AM

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 · 25th May 2006, 05:27 AM

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.

24th May 2006, 06:24 PM	#1
lgreen diyAudio Member Join Date: May 2003 Location: San Diego, USA	where to get 0.1 ohm 2W 0.1% resistors? 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. __________________ My DIY audio projects- PartTimeProjects.com.

24th May 2006, 08:04 PM	#3
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	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) __________________ Mads K

25th May 2006, 01:43 AM	#9
tiltedhalo diyAudio Member Join Date: Sep 2005 Location: Melbourne Florida	.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

25th May 2006, 05:27 AM	#10
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	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. __________________ /Per-Anders (my first name) or P-A as my friends call me

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24th May 2006, 06:54 PM	#2
Bazukaz diyAudio Member Join Date: Nov 2005 Location: Vilnius	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.

24th May 2006, 10:30 PM	#7
RDV diyAudio Member Join Date: Sep 2005	I used 1% for mine and it works fine. HTH RDV

24th May 2006, 11:09 PM	#8
DIAR diyAudio Member Join Date: Jun 2004 Location: Capital City Area	If I need a matched pair I buy a bunch of 1% resistors, measure them and choose a pair with same resistance.

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