Recent content by johnerbes

  1. J

    Analog Circuit Design for Fuel Tank Sending Units: Help Needed

    Now that we have this fully analyzed, does anyone have any thoughts on an appropriate circuit? For the prototype circuit, let's assume that the resistance of the sending unit is 5 ohms full and 100 ohms empty and that both ends of the variable resistor are accessible. The Weston meter movement...
  2. J

    Analog Circuit Design for Fuel Tank Sending Units: Help Needed

    I have a friend that is trying to create a collection of authentic instrumentation for an old car replica he is building. I happen to have a bunch of old Weston meters. Weston actually made voltage and amperage meters for automotive applications in the old days that looked just like their other...
  3. J

    Analog Circuit Design for Fuel Tank Sending Units: Help Needed

    This isn't for my car. It's for a different application.
  4. J

    Analog Circuit Design for Fuel Tank Sending Units: Help Needed

    I'm about 95% certain that the tank sending unit resistor is isolated from ground. Many gas tanks are plastic these days. Also, a reliable ground through the tank attachment straps on even a steel tank over time is iffy. In the recent past (30?) years, fuel gauge circuits appear to consist...
  5. J

    Analog Circuit Design for Fuel Tank Sending Units: Help Needed

    Typical fuel tank sending units have a resistance of 0 to 10 ohms in the full position and 90 to 240 ohms in the empty position. I have an old Weston 50uA meter I would like to use as a fuel gauge. I need help with designing an analog circuit that will drive the 50uA Weston meter from the tank...
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