variable resistor tool

members,

I recently worked with a fella who produced out of a bag a variable resistor tool

in short it was used for replacing/tricking thermistors on AC systems.

he said after he found it in my pocket they were available on line, OK please give a clue where................................................................................

I have looked at making one as parts could be sourced from maplin RS ect but this box of tricks was just right for the job, croc clips/prongs and a twist selector for ohms

any clues on where to get one?

Variable resisitor tool?... is that the same as a 10k pot? If so they're available at RS, Farnells, and Maplins as you've seen. Does your mate sustitute the thermistors with a pot then trim the resisitance to match the thermistors design parameters, then measure the the setting value of the pot?

Hisuperswill.
I may have the wrong idea, but what I have is old fashioned by todays standards.
It is known as a decade box.
A search under that title may clarify?
Grizzly

Quote:

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Originally Posted by chilliwilly

Variable resisitor tool?... is that the same as a 10k pot? If so they're available at RS, Farnells, and Maplins as you've seen. Does your mate sustitute the thermistors with a pot then trim the resisitance to match the thermistors design parameters, then measure the the setting value of the pot?

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thats the toy

Quote:

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Originally Posted by Grizzly

Hisuperswill.
I may have the wrong idea, but what I have is old fashioned by todays standards.
It is known as a decade box.
A search under that title may clarify?
Grizzly

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Grizzly,

I will look into this

Hi superswill
the resistances I have come across are 10K, 8K, 5K, 3K and 2K for space temps and something like 180ohms on an oil temp. So best bet is to get one with a trim pot similar to what chilliwilly has suggested. That way with any sensor you can have control over the dead band of the switching too.

Hi Paul,

Is is something like these.

http://cpc.farnell.com/cebek/edu-005...box/dp/HK01092


http://cpc.farnell.com/tenma/72-7270...box/dp/IN04175

i made one from cpc catalogue if you need any help they have a good technical line

Quote:

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Originally Posted by marc5180

Hi Paul,

Is is something like these.

http://cpc.farnell.com/cebek/edu-005...box/dp/HK01092


http://cpc.farnell.com/tenma/72-7270...box/dp/IN04175

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just the ticket, ordered two, thank you marc

Let me know if they work will you?

I was thinking of ordering one of them a few weeks back.

Quote:

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Originally Posted by marc5180

Let me know if they work will you?

I was thinking of ordering one of them a few weeks back.

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the Guinea pig will test and update

Go for a 10 turn pot as a single turn pot will not give you the accuracy

Quote:

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Originally Posted by mbreward

Go for a 10 turn pot as a single turn pot will not give you the accuracy

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Thank for for the info

http://uk.rs-online.com/web/search/s...ubRange=Decade Boxes#breadCrumb

Not got one myself but got a mate who swears by his..

Ginge :)

Quote:

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Originally Posted by marc5180

Let me know if they work will you?

I was thinking of ordering one of them a few weeks back.

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Marc,

is working well, i went for the CPC one

a few extra "mods" later mind

see link:

https://www.yousendit.com/download/M...NmMyWGMwTVE9PQ