Please help a newbie with a LM3914 circuit

[Hollister]

Hi, I was wondering if anyone could help me with a problem i've got!

I've got a problem I need to solve, and basically I think I can almost solve it with a circuit using a LM3914. Trouble is I really dont know much about electronics and although I think I can almost get to grips with the circuit design I can't quite figure it out.

Could someone design this circuit for me please!?!?


I have a variable resistance that ranges from about 15ohms to 195ohms, and I need to light up the LEDs in a display like **broken link removed** along that resistance range. I was looking at using a LM3914 to do this.

So basically when the variable resistance is 195ohms 1 LED wants to be active and when the resistance is 15ohms all are lit. The whole thing wants to run off a 9V battery, and some trim adjustment for the min and max resistance would be nice.


If anyone could help I would be so gratefull! Thanks

 

[Hollister]

For a bit more background, I need a way to display the fuel level in my rally car and the stock method isn't going to work any more.

It is the float in the fuel tank which gives the 15ohms to 195ohms range.

I have looked at the similar projects on this forum but still can't figure out how to make it work for me in particular.

I've been doing a bit more research and think now that I will have to put a voltage regulator in to deal with the variable voltage that a battery (or a feed from the car, i'm not fussed which really) will produce. Is that correct?

 

[Hero999]

https://www.electro-tech-online.com/threads/help-me-build-a-gas-gauge.34321/

 

[Hollister]

https://www.electro-tech-online.com/threads/help-me-build-a-gas-gauge.34321/

Thats one of the threads I have been looking at.

Would one of the final schematics (this one) ideally have a voltage regulator to ensure that the input is always 12V (as it will be higher than that when running)?

I can get away without having it I think, as it will only be used when the engine isn't running and it doesnt have to be massively precise anyway.