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 Post subject: Temperature sensor resistance
PostPosted: Sun Dec 10, 2017 11:28 am 
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Joined: Mon Feb 25, 2008 11:44 am
Posts: 345
Location: Northern Ireland
I'm setting up an ebay speedo that includes a fuel gauge but no temperature gauge. I am trying to connect my temp sensor to the fuel gauge so that the fuel gauge position will indicate the temp.

My temp sensor has a resistance of 150 ohms at 50c and 15 ohms at 100c.

The fuel gauge reads empty at about 450 ohms and full at about 50 ohms

If i could somehow multiply the resistance of my temp sensor by 3 it would work perfectly.
Any electronics experts know how to multiply resistance? Cant find anything on google


Last edited by trix on Sun Dec 10, 2017 5:49 pm, edited 1 time in total.

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 Post subject: Re: Temperature sensor resistance
PostPosted: Sun Dec 10, 2017 12:23 pm 
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Joined: Sun Oct 28, 2012 6:38 pm
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Location: Spielberg, Austria
I think it should be possible with 2 resistors - one resistor in series to the temp sensor for range correction and one parallel for the multiplication factor...

Just what came to my head while reading...

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 Post subject: Re: Temperature sensor resistance
PostPosted: Mon Dec 11, 2017 7:49 pm 
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Joined: Tue Jul 19, 2011 7:49 pm
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Location: Toulouse France
You can't fight the Ohm law.
To increase your resistance you must add another resistor in serial.
Total resistance will be the sum of each one in serial.
But you won't have the desired range.
Example : add 300 ohms in serial : resulting resistance will vary between 315 and 450 ohms.
Only way to get the range 50 - 450 would be to put 3 temperature sensor in serial !!
Forget about it.


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 Post subject: Re: Temperature sensor resistance
PostPosted: Tue Dec 12, 2017 6:44 pm 
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Joined: Mon Feb 25, 2008 11:44 am
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That's right, adding a resistor in series wont give me the range. Adding a resistor in parallel wont give me the range either.

I've bought a couple of other temp sensors on ebay to see what their range is. I've also put some queries on electronics forums to see if someone is aware of a circuit I could build to achieve this.


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