Fuel sensor with a fuel gauge and ADC

[sudarshann]

I have a fuel sensor in the bus which gives me 0-200 ohms.
The fuel gauge is connected to it and it works on 24V.

so the problem is i need an ADC to be connected to it. IF i connect the ADC device 0-5V (no idea on what is the potential divider in it)alone it works or gauge alone it works.

I want the both to work i cant get it right.

The sensor terminal gives me around 10V in half tank so i made this divider in the output

24V -> 780 ohms -> ADC tapping -> 100 ohms -> gnd.

It gives me arround 4 V and the voltage varitation is not that much good. the ADC device gives me only arround 70% to 90% of the reading if do so. the lower values are not got.

Please suggest me a solution for solving this.

Thank you

 

[crutschow]

Assuming you are leaving the fuel gauge connected with the ADC then you need a higher impedance voltage divider so you don't load the circuit. Try 7.8k and 2k to start.