<will use a resistor network. For the discussion, I had the ohm values swapped, it is 410 ohm empty and 15 ohm full>

i have added a second fuel tank to my rig. both tanks use the same 15 ohm empty to 410 ohm full fuel senders (resistive pots?). The gauge is a voltage based gauge and reads the voltage drop across the sender resistance relative to 12v.

I want to build a simple circuit that switches the resistance the gauge sees based on the resistance of tank 2.

example a. Just filled up. Both senders read 410 ohm. gauge shows full and should be reading the resistance of tank 2.

example b. Tank 2 is empty, tank 1 is full. Tank 2 reads 15 ohm, tank 1 reads 410 ohm. Gauge should show full, and display tank 1 Value.

example c. Tank 2 and tank 1 are empty, both at 15 ohm. Gauge shows empty, and is displaying tank 1

I have a couple basic parts kits with resistors, diodes, and npn and pnp transistors available. I’ve been reading around and searching and found some thermistor and photo resistor examples that are in the ballpark, the part I’m having trouble with is where to ‘insert’ the fuel sender pots.

sadly the tanks are not the same volume, so a simple divider won’t work, but I’m totally open to a ratio divider network.the tank volumes are tank 2 12 gal and tank 1 25 gal.

thanks in advance!

i have added a second fuel tank to my rig. both tanks use the same 15 ohm empty to 410 ohm full fuel senders (resistive pots?). The gauge is a voltage based gauge and reads the voltage drop across the sender resistance relative to 12v.

I want to build a simple circuit that switches the resistance the gauge sees based on the resistance of tank 2.

example a. Just filled up. Both senders read 410 ohm. gauge shows full and should be reading the resistance of tank 2.

example b. Tank 2 is empty, tank 1 is full. Tank 2 reads 15 ohm, tank 1 reads 410 ohm. Gauge should show full, and display tank 1 Value.

example c. Tank 2 and tank 1 are empty, both at 15 ohm. Gauge shows empty, and is displaying tank 1

I have a couple basic parts kits with resistors, diodes, and npn and pnp transistors available. I’ve been reading around and searching and found some thermistor and photo resistor examples that are in the ballpark, the part I’m having trouble with is where to ‘insert’ the fuel sender pots.

sadly the tanks are not the same volume, so a simple divider won’t work, but I’m totally open to a ratio divider network.the tank volumes are tank 2 12 gal and tank 1 25 gal.

thanks in advance!

Last edited: