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trigget 12V relay from 1.8V

Michel Leger

Aug 4, 2017
1
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Aug 4, 2017
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I have a vehicle transmission that the gears are displayed using a resistor pack.
P - 1V
R - 1.8V
N - 2.6V
H - 3.4V
L - 4.4V

I want to put reverse lights on the machine, so when the shifter is in reverse i need a circuit to trigger a 12Volt relay from the 1.8V.
Can anyone tell me how to achieve this? I was looking at the LM311 Comparator but im confused on how it works.
Thanks!
Mike
 

BobK

Jan 5, 2010
7,682
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Jan 5, 2010
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7,682
You would use two comparators to determine if the signal was 1.8V.

One would signal true if the signal was greater than 1.4V and the other set to true if the signal is less than 2.2V. These points chosen to be halfway between the surrounding values.

Then if both are true, the signal must be 1.8V.

Bob
 

kellys_eye

Jun 25, 2010
6,514
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Jun 25, 2010
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6,514
....otherwise known as a 'window comparator' (Google will reveal)
 

Kiwi

Jan 28, 2013
471
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Jan 28, 2013
Messages
471
Just be careful that you don't put much load on the circuit and drag the voltage down.
 
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