I want toadd a set of gauges to my fuel management system. It will require one for each tank and 3 standard gauges take up to much room and cost a bunch so I am going to DIY it. Follow me through on this:
The sender is a variable resistor with a range of 240 Ohms empty to 33 Ohms full. If I put a 240 ohm resistor in series with the sender, feed it 3.3V and measure the voltage across the 240 Ohm resistor I will get a voltage from 1.65V empty to 2.9V full. That is a range of 1.25V in a more or less logarithmic curve. If I feed this voltage to an LM3915 LED driver I can display the tank levels on a 10 segment LED array.
There is only one problem. How do I set the zero to 1.65V?