Help Choosing Correct Resistor

Thread Starter

Antony Lawlor

Joined Apr 3, 2019
2
Hi,

I am trying to figure out which type of resistor I need to be able to achieve 120c as per the image attached. I know the reference voltage is 5v and that the voltage after resistance is introduced 0.28 and that the resistance I need is 1.18kohms (1180ohms) - i'm pretty sure it's not as easy as just picking up any 1.18k resistor so hoping you guys can help - not to clued up on ohms law and resistor banding etc.

Thanks,

 

AnalogKid

Joined Aug 1, 2013
8,310
What do you mean by "achieve 120c"? Please post your intended schematic so we can see what you are trying to do? Do you want to

be able to read the temperature accurately over a range of temperatures

just detect when the temp is above/below a trip point

something else?

ak
 

Thread Starter

Antony Lawlor

Joined Apr 3, 2019
2
The a car coolant temp sensor - trying to test new rad fans i've installed CTS kicks them in - figured it out now 0.5k resist got the temp gauge into the red.
 

Wolframore

Joined Jan 21, 2019
1,650
Why not try a 50K potentiometer? You can actually change the resistance. Just need to figure out what power rating it should be.

I'm pretty sure it's low voltage signal. It's up to you to check and make sure this is correct for sizing the component correctly.

I would put a 1.2 k resistor in series so it can't go lower.

Here's the link for color code:https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band
Bad boys ra@e our young girls but violet goes willingly...

Caution - if you mess this up you could possibly burn out this function or worse yet your ECM... so you're warned...
 
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