Does anyone know where to get a specially ordered resistor

Thread Starter

johnboyman

Joined Jun 1, 2019
17
Hey guys. Does anyone know where to get a specially ordered resistor. I need a size of resistor that is not a common size and i don't want to instead use a bunch of resistors in series because i already am using a bunch of resistors in series. It left confused. I need a specialty resistor like a custom. Is this possible? Thanks.
 

WBahn

Joined Mar 31, 2012
24,691
Hey guys. Does anyone know where to get a specially ordered resistor. I need a size of resistor that is not a common size and i don't want to instead use a bunch of resistors in series because i already am using a bunch of resistors in series. It left confused. I need a specialty resistor like a custom. Is this possible? Thanks.
"Specially ordered" implies that you need to order it from someplace that distributes for that manufacturer. There's no generic answer -- you need to find a distributor for that manufacturer.

You have provided basically no information that we can leverage. We don't know if you are talking about a tiny surface mount resistor or a huge power resistor a foot or two in length.

What is uncommon about the size? What size is is? What resistance is it? What type of resistor is it? What tolerance is it? Who's the manufacturer? What markings are on it? What is it being used for?
 

djsfantasi

Joined Apr 11, 2010
5,586
Ahhh! Another problem for the psychic!



shteii01, you’ve been around long enough to know that problems that require the psychic can’t be solved in any forum!
 

MrChips

Joined Oct 2, 2009
19,270
If you need a special value resistance, common practice is to use a fixed value resistor and add a trimmer resistor in series, for example,

98% fixed resistor + 4% trimmer
95% fixed resistor + 10% trimmer
90% fixed resistor + 20% trimmer

or any similar arrangement depending on the range of adjustment and precision you need.

Or you can often get the exact value resistance by using only two fixed values either in series combination or parallel combination.
 

shteii01

Joined Feb 19, 2010
4,667
Ahhh! Another problem for the psychic!



shteii01, you’ve been around long enough to know that problems that require the psychic can’t be solved in any forum!
I follow: "Anything is possible, but some things are highly unlikely."
 

oz93666

Joined Sep 7, 2010
668
Nobody in practice needs such a resistor .... common resistors have tolerances of 20% or 10 % exceptionally accurate resistors have 5% tolerance !

A 1,000 ohm resistor with a 5% tolerance could be anything from 950 to 1050 Ohms !!!
 

WBahn

Joined Mar 31, 2012
24,691
Nobody in practice needs such a resistor .... common resistors have tolerances of 20% or 10 % exceptionally accurate resistors have 5% tolerance !

A 1,000 ohm resistor with a 5% tolerance could be anything from 950 to 1050 Ohms !!!

Huh???

I just checked DigiKey and out of over 330,000 thru-hole resistors they only have five that are 20% tolerance -- and they are all 1 W with resistances ranging from 1 MΩ to 20 MΩ. They have about 7000 listings for 10% and 65,000 for 5%. Now compare that to over 180,000 for 1%, over 63,000 for 0.1% and over 4500 for 0.01%. They even have 228 listings for 0.001%.

Looking at chip resistors, they have about 1700 for 20%, 1800 for 10%, 79,000 for 5%, 283,000 for 1%, 160,000 for 0.1%, and 6500 for 0.01%

Methinks someone in practice has needs for such a resistor.
 

crutschow

Joined Mar 14, 2008
23,317
i don't want to instead use a bunch of resistors in series because i already am using a bunch of resistors in series.
If you are already "using a bunch of resistors in series" then why not just pick the values to get the total resistance value you need?

Tell us exactly the type and value of the resistor you need.
 

Danko

Joined Nov 22, 2017
791
Hey guys. Does anyone know where to get a specially ordered resistor. I need a size of resistor that is not a common size and i don't want to instead use a bunch of resistors in series because i already am using a bunch of resistors in series. It left confused. I need a specialty resistor like a custom. Is this possible? Thanks.
Recently I bought:
1. High Voltage Resistor Series 400, Model 400.15, 1 Gig, 1%, 10 ppm/C, NON-Inductive, 90 kV, 20 Watts, Silicone Coating
instead a bunch of resistors 5.1 Meg
here:
www.high-voltage-resistors.net/index.aspx?pageid=610652&prodid=9731413
and
2. 200 kV 0.1 A High Frequency silicon stack 2CLG200KV-100mA
instead a bunch of diodes 1N4007, 1000 V
here:
https://www.hvdiode.com/product/hvsilicon/GP/29.htm

So, no problem.
 
Last edited:

Alec_t

Joined Sep 17, 2013
10,357
I'm sure someone in China would make a custom resistor for you; providing you order 100,000 or so ;).
But why do you need a very precise value? Won't the tolerance of other components in your mystery circuit dominate the effect you're seeking?
 

OBW0549

Joined Mar 2, 2015
2,982
.... common resistors have tolerances of 20% or 10 % exceptionally accurate resistors have 5% tolerance !
I haven't seen a 20% tolerance resistor in many, many years, and a 10% resistor only rarely. 5% resistors are quite common, but calling them "exceptionally accurate" is just plain silly. They're fine as pullup resistors on digital logic inputs, but I don't use them for much else. I use 1% resistors for nearly everything and I don't consider them "exceptionally accurate"; I reserve that term for 0.1% and 0.01% parts.
 

MisterBill2

Joined Jan 23, 2018
3,863
The resistance value and power rating would not provide a clue as to what the product might be. And I will suggest that if the resistance value must be that precise then either an adjustment scheme needs to be considered or else the whole design is in question. If any production item needs tighter than 1% tolerance then it is not suitable for production. The immediate problem will be very poor production yield, because the real world does not work that way. Transistors and diodes are not produced to that very tight tolerance.
BUT, there are resistors produced to 0.1% tolerances, readily available for quite high prices, even from places like DigiKey. But you do need to ask because normal designs simply do not need that level of accuracy.
 

WBahn

Joined Mar 31, 2012
24,691
The resistance value and power rating would not provide a clue as to what the product might be. And I will suggest that if the resistance value must be that precise then either an adjustment scheme needs to be considered or else the whole design is in question. If any production item needs tighter than 1% tolerance then it is not suitable for production. The immediate problem will be very poor production yield, because the real world does not work that way. Transistors and diodes are not produced to that very tight tolerance.
BUT, there are resistors produced to 0.1% tolerances, readily available for quite high prices, even from places like DigiKey. But you do need to ask because normal designs simply do not need that level of accuracy.
Let's keep in mind that the TS has said nothing about the resistance value needing to be precise, only that the size of the resistor is not common (to the best of his knowledge). It could be a 20% resistor that is odd-sized, for all we know. As is so common, the TS won't provide any details. It would sure help to know what is uncommon about the size of the resistor he is looking for, but that appears to be some closely held secret.
 
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