I need to simulate a 1200Ω fuel sender with an arduino, so I can control the fuel gauge.
The fuel gauge has one wire which it supplies with an unknown current and voltage, where the voltage is no larger than 12V and the current no larger than 50mA. The fuel sender is a resistor to ground. It's this resistance to ground I need to simulate.
I could go to the trouble of finding and fiddling with a digital potentiometer, except for the large voltage and current requirements.
It seems like I should be able to accomplish this with a ULN2803 and a series of resistors. I can use 6 outputs on the Arduino to control this driver, which then sinks it's outputs. (the other two outputs will drive dashboard indicators)
The simplest method would be to connect 6 different resistors, each representing one fuel level, and activating only one at a time.
A more complex solution would involve an R-2R ladder, but those designs are meant to work with digital I/O that both sources and sinks current, whereas I'm seeking merely to sink current to avoid having to deal with the 12V issue.
- Is there a simple solution with the ULN2803 and some resistors that will give me more control than just 6 levels?
- Is there a better way to drive a fuel gauge such as this?