57.6KOhm Resistor 'Carbon Composite'

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pre65
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#16 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by pre65 »

There is a web site that has calculators to sort out series and parallel resistor values.

IF you have the time and patience you may get nearer to 57.6K ohm than the earlier example I gave.

https://www.electronics2000.co.uk/calc/
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#17 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by Nick »

There is a web site that has calculators to sort out series and parallel resistor values.
It sort of doesn't matter, you can't make a 0.1% resistor by combining 1% resistors. You will still have to measure them with a device that has at least 0.1% accuracy. You don't say what tolerance you actually need, and assuming you haven't got a meter that is calibrated AND accurate to the required tolerance, your best option is to buy a high tolerance metal film 57k6 resistor and use a bridge (simple to make especially for resistors) to match one or more carbon comp to your known reference standard.
The tighter the tolerance the better.
This will get you to 0.1%

https://uk.rs-online.com/web/p/through- ... s/7546702/

Beyond that starts to cost.

The fact that the value looks like a E96 one suggests that whatever the actual value wanted, the designer picked from a 1% range to get the closest to the actual desired value, so in practice using more that 1% will just be giving you a higher accuracy copy than the thing that's being copied.

The advantage that higher than 1% will give you is potentially better matching if you have more than one channel. Of course if the resistor is part of a network, then there is no point in using a 0.1% part if its combined with 2% parts. Again, selecting against a known standard or a calibrated meter is the best way, though an un-calibrated meter is fine if you just care about channel matching.

If you really want to enter the world of metrology talk to Andrew L.
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#18 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by Mike H »

Just had a thought – in my own experience, if I buy say 10 off of XXX resistors with YYY value, quite often they tend to be from the same batch, so are very alike in match of value. In that case, you could get 10 off 56k carbon comp and at least two are going to be near enough twins. How close they are to 56k may be another matter but at least will be the same, if value matching is important. And as suggeted by others, there may be temp variations, but again hopefully the pair will behave the same.

If it's the case that the value must be 57.6k, then it's a long and possibly expensive search to find two carbons with that value. Or, go for high tolerance metal film.
 
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#19 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by pre65 »

Mike H wrote: Thu Oct 31, 2019 5:19 pm Just had a thought – in my own experience, if I buy say 10 off of XXX resistors with YYY value, quite often they tend to be from the same batch, so are very alike in match of value. In that case, you could get 10 off 56k carbon comp and at least two are going to be near enough twins. How close they are to 56k may be another matter but at least will be the same, if value matching is important. And as suggeted by others, there may be temp variations, but again hopefully the pair will behave the same.

If it's the case that the value must be 57.6k, then it's a long and possibly expensive search to find two carbons with that value. Or, go for high tolerance metal film.
OR, use a potentiometer ? :?:
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#20 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by Nick »

OR, use a potentiometer
You still have the problem of measuring them to a known accuracy.
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#21 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by JohnG »

I have informed the EE/Builder of the comments received up until yesterday about the restrictions being shared about Carbon Composite Types.
The EE was keen to let me participate in the parts purchasing process, possibly resulting with extended info, that there might have been a direction to a supplier to purchase high quality ones at a more reasonable price than a used supplier.
I have been informed that there are resistors available to overcome the raised issues, and meet the required value, so I can rest assured.
These parts will be purchased from the usually used supplier, as I failed to find the value to be used on Texas Components and have not come back with any other suppliers to be investigated.
This is my first foray into such a activity, as a result I have picked up some very good pointers that I have not had to consider before.
Lets see what I am given a free reign to search out next.
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#22 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by andrew Ivimey »

Don't you think this is all a bit silly....
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#23 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by pre65 »

andrew Ivimey wrote: Thu Oct 31, 2019 10:13 pm Don't you think this is all a bit silly....
Perhaps,perhaps,perhaps. :lol:
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#24 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by andrew Ivimey »

Now there's a babe!
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#25 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by Nick »

I have been informed that there are resistors available to overcome the raised issues, and meet the required value, so I can rest assured.
Trust me, I am a doctor...
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#26 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by JohnG »

In my view, The request for Copper Cap's went down really well, the request for Resistors have taken on a different route.
I assume there are loyal followers of certain
types.
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#27 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by pre65 »

It may (possibly) be that you are asking for something that is non existent in reality, as in the original request.

That, together with the "secrecy" of the intended use, has (I suspect) elicited a degree of wee wee taking.
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#28 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by pre65 »

Just thinking aloud.

John has not specified the type of fixing this resistor should have. I was assuming "through hole" but it could be SMD ?

If through hole could one use an SMD by soldering on wire ends ?

And would thick film SMD resistors have the "qualities" that carbon composition have ?

If my thoughts are total bollox I apologise. :)
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#29 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by Nick »

In my view, The request for Copper Cap's went down really well, the request for Resistors have taken on a different route.
That's because the two questions were very different.
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#30 Re: 57.6KOhm Resistor 'Carbon Composite'

Post by IslandPink »

pre65 wrote: Fri Nov 01, 2019 1:39 pm And would thick film SMD resistors have the "qualities" that carbon composition have ?
Good point, I have tried than and would say 'yes' they have the key properties of non-inductive carbon when used in the signal path. You have to buy the biggest ones they make, if you want to have any chance of soldering them to anything !
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