Changing the impedance proportion

Discussion in 'General Electronics Chat' started by orwikcons, Jun 27, 2008.

  1. orwikcons

    Thread Starter Member

    May 2, 2008
    22
    0
    I have a gauge (for car fuel) that responds to impendances: 35 Ohms (empty tank), up to 300 Ohms (full tank), and I have a LPG giver that gives impendances 5kOhms (empty tank) up to 15kOhms (full tank). What circuit do I need to adjust LPG giver to gauge's scale? I tried to calculate one resistor in series with LPG giver, and the second parallel with it, but I've got negative values, so it is impossible in that way.
     
  2. Norfindel

    Active Member

    Mar 6, 2008
    235
    9
    Can you explain this better?

    If i understand it correctly, you have some instrument designed to use a level measurement device with a resistance from 35 to 300 ohms, but the one you have has 5k to 15k?
     
  3. orwikcons

    Thread Starter Member

    May 2, 2008
    22
    0
    Yes, that is what I wanted to say, sorry, my English is not so good...
     
  4. Norfindel

    Active Member

    Mar 6, 2008
    235
    9
    Mine either, probably that's the problem, anyways :D

    How is the instrument connected to the sensor? What's the instrument measuring?

    If the instrument is measuring current thru the sensor, the problem is that your sensor would draw a lot less of it. Probably you would need to use some active circuit to draw a higher current, depending on the level of the resistive sensor, or just change the sensor for the correct one. I just don't see how could you do something with passive components (other than replacing the sensor).
     
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