Oil level sensor circuit

Hello,

I need some help to build a circuit for the oil level in order to simulate the process on a real car with the help of resistors and/or capacitors, etc.
It is supposed that we have an injection of 210 mA constant current, sent by  vehicle cluster once each minute. 
The idea is to measure a difference between two consecutive voltage measurements to obtain a voltage drop which reflect a specific level ( for exemple, for 40 mV it is considered that the level is FULL and for 450 mV we have the MIN level).

Please find attached two pictures which might help you to better understand what I want.

Thank you in advance!

Hi Danut C.,

Based on the images you've provided, you have "U" and "R" as the variable parameters while "I" as the constant. You need an additional known component such as resistor that will help you to determine the unknown component.

You can make use of maximum power transfer circuit or the theorem itself

I = (V) / (Rs+RL) -> PL = (I^2)(RL)

Try to check the circuit below
-> https://www.eeweb.com/electronics-quiz/electrical-electronics-industrial-equipment

Determine the known parameter/s you have, so you can determine the unknown/s you really need to have that correspond to the level of Oil.

Hope it helps.

God Bless.

Best,
Neil

Hi Neil,

Thank you very much for your answer. In the picture attached "oil level circuit" you can find a circuit that I've built and for many measurements I obtain different values (from 30mV to 370mV) for the differential voltage even if I discharge the capacitor. I don't know why this happens.
The idea is to obtain a stable differential voltage for the resistor value of 1,6 ohms. Then with the help of a switch I want to change the resistor to obtain another differential voltage which reflect a certain oil level.

Thank you for your help!

Have an amazing day,
Danut