# How to subtract 10 ohms from a 200 ohm resistive load?

#### HLOW

Jan 24, 2013
12
I'm try to calibrate an auxiliary automotive cooling water temp gauge. When I submerse the sensor in boiling water the gauge reads about 90C... The sensor reads about 210 ohms (at 100C). I would like it to be about 200 ohms so the gauge reads correctly. I realize the low end will not be perfectly accurate but I'm not concerned with that.
Thanks for any insight!!!
...

#### Bluejets

Oct 5, 2014
6,924
Op amp or a uC using the map function.

#### duke37

Jan 9, 2011
5,364
You can put a resistor in parallel
1/A + 1/B = 1/C
so
1/210 + 1/D = 1/200
or
1/D = 1/200 - 1/210
resistor D = 4200
Chose a resistor of the nearest preferred value say 3k9Ω or 4k7Ω

#### HLOW

Jan 24, 2013
12
You can put a resistor in parallel
1/A + 1/B = 1/C
so
1/210 + 1/D = 1/200
or
1/D = 1/200 - 1/210
resistor D = 4200
Chose a resistor of the nearest preferred value say 3k9Ω or 4k7Ω
THANK YOU!!!

Jun 10, 2015
2,893
or 4.22 K at 1%.

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