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Resistor Question

Discussion in 'Technical and Troubleshooting Torque' started by carpetbelly, Sep 5, 2011.

  1. Ok,

    So I've got some more info but need somehow to achieve what I want and hopefully someone here with an understanding of electronics might be able to help

    The new gauge I've got works on the following principle...
    low ohms reading, full tank... High ohms reading, empty tank basically...

    Unfortunately the sender in the Hyo reads the following (from what I've been told)
    90-105 ohm at full

    50-60 at half

    leas than 10 ohm at empty and flashing..

    So the other way around. Is there any way I can 'reverse' the Ohms reading coming from the fuel sender? Electrics was never my thing, my brains melting even thinking about it lol
  2. Yep, use an op amp in reverse biased mode. Would take lots of screwing around to calibrate though.
  3. Tippex the "F" to "E" and visa-versa
  4. ****in lol dot com!!! :D
  5. Should be able to do it with a transistor and a few resistors... old school.

    I would be surprised if google does not turn up something prebuilt to do the job already.
  6. Depends on how the gauge is used. The resistor could be limiting current through a wound gauge, or it could be looking for a voltage drop across the sender. You will need to know which one before you can continue. I beleive most work by a current going into the gauge. Inverting a current is hard, and not something you could really do.
    You laughed at the tipex comment, but seriously that would be the easiest.
  7. Install your cluster upside down.
  8. I know I laughed but I am considering reading the fuel gauge backwards hehe
    So as it gets near full on the digital readout (if it does so I've had a small ride to try to take some gas out of the tank) then I know it's actually getting close to empty lol
  9. My motto is: If it's worth doing, it's worth overcomplicating. Therefore I retract my op amp suggestion and now recommend a microprocessor or a Sharc DSP.

    Or, maybe we can roll a neural net in a FPGA. NERD FIGHT!
  10. Whats the gauge in question?
  11. well, it's a koso rx2...
    In fact, im gonna blow off the fuel gauge as I really dont think the sender I have in the tank will do that. By teh wiring spec I've now looked at for the hyo with the fuel lights rather than a guage it looks like it's two seperate resistors driving a 1/2 tank light and empty light.

    But I could use a couple of spare warning lights on the gauge to give me a 1/2 tank and empty with the oil and engine light. But will still have to look at some resistors as the gauge uses LED to light them up by the looks of it where as the bulbs on the normal dash are iridecent bulbs. Also the warning lights are coming on right away as well. Luckily both the warning lights are -v same as the original so I can use them, just gotta get the resistances right.
  12. I had a Land-Rover years ago with a non-standard instrument cluster whose gauge was similarly incompatible with the sender. Used to read 1/2 when the tank was brim full and was jammed against the F stop when the tank was empty. You get used to it fairly quickly :D.
  13. Sounds pretty futile.
  14. You will be assimilated..
  15. futile, but fun... mucking around with stuff is half the fun of anything :D