hi everyone,
I need a bit of help working out how to create a circuit, my overall project is to create a whole guage cluster from scratch. tach, spedo, temp, fuel, the whole lot. I already have a working circuit for tach and spedo, I'm now up to temp and fuel. I was thinking of using the lm3194 for both temp and fuel, just one of the basic circuits from the datasheet.
im still a bit of a noob so excuse me if I make any simple mistakes, the inputs from both temp and fuel sensors are pretty simple, both use a potentiometer so as fuel/temp increases/decreases the resistance changes. my thought was to bridge pins 4 and 5, replace R2 with the pot in the sensor, that way as ref hi decreases the display will light up. but after thinking about it this would not work, to begin with the voltage on pin 5 would need to be higher than pin 4, and even then the display would increase exponentially instead of linear. I am yet to think of another way to hook up the sensors. thats my first problem, the only other Idea that I have had is to use the sensor as part of a voltage divider to pin 5 but not sure how well that will work. others that I have thought of are as follows.
as fuel drops resistance decreases (guage needs to drop from High to Low)
as temp drops resistance increases (guage needs to drop from High to Low)
so circuits would need to be different because I want to use the IC's in Bar mode. if it were dot mode I could simply flip one upside down. but that would be cheating.
like I said I'm a bit of a noob, it took me about 3 months to finally get a working Tach and spedo so if i've missed anything obvious or made any obvious mistakes feel free to have a good laugh at my expense.
thanks in advance.
P.S. feel free to ask me if you want the Tach or Speedo circuit. they are both one and the same and just need to be duplicated for the second application.
I need a bit of help working out how to create a circuit, my overall project is to create a whole guage cluster from scratch. tach, spedo, temp, fuel, the whole lot. I already have a working circuit for tach and spedo, I'm now up to temp and fuel. I was thinking of using the lm3194 for both temp and fuel, just one of the basic circuits from the datasheet.
im still a bit of a noob so excuse me if I make any simple mistakes, the inputs from both temp and fuel sensors are pretty simple, both use a potentiometer so as fuel/temp increases/decreases the resistance changes. my thought was to bridge pins 4 and 5, replace R2 with the pot in the sensor, that way as ref hi decreases the display will light up. but after thinking about it this would not work, to begin with the voltage on pin 5 would need to be higher than pin 4, and even then the display would increase exponentially instead of linear. I am yet to think of another way to hook up the sensors. thats my first problem, the only other Idea that I have had is to use the sensor as part of a voltage divider to pin 5 but not sure how well that will work. others that I have thought of are as follows.
as fuel drops resistance decreases (guage needs to drop from High to Low)
as temp drops resistance increases (guage needs to drop from High to Low)
so circuits would need to be different because I want to use the IC's in Bar mode. if it were dot mode I could simply flip one upside down. but that would be cheating.
like I said I'm a bit of a noob, it took me about 3 months to finally get a working Tach and spedo so if i've missed anything obvious or made any obvious mistakes feel free to have a good laugh at my expense.
thanks in advance.
P.S. feel free to ask me if you want the Tach or Speedo circuit. they are both one and the same and just need to be duplicated for the second application.