Just planning should I ever convert a car to run dual fuel i.e. Petrol and LPG/Autogas and decided I don't much like the way the gauges are done in most installations, so I decided I wanted to find a solution I prefered.
Currently most LPG conversion come with a small square gauge thats just stuck on the dash somewhere and looks awful aesthetically (pic 1), I came to the conclusion that using the standard car fuel gauge would probabally look best.
I decided I would use Yenka to try and create a solution and using a few transistors (PNP & NPN) I thought I had come up with the answer. I have 3 LEDs in the diagram, 2 to indicate the fuel source and 1 to indicate the gauge getting the feed. The diagram (pic 2) should make it fairly clear what I was attempting to achieve, but I overlooked one thing that I think would cause major issues.
Fuel gauges/fuel senders work on resistance and I've added and used LEDs, resistors and transistors which I assume will all help to give a false reading.
How could I switch between two separate fuel sender feeds without affecting the resistance values and therefore have a false reading on the gauge?