Lying to a sensor

Discussion in 'The Projects Forum' started by Schutzengel, Jun 27, 2009.

  1. Schutzengel

    Thread Starter New Member

    Jun 27, 2009
    2
    0
    I have a small thermocouple that I wish to variably alter the perceived voltage without harming the original signal, so that variations in the original will be passed along to the receiving side. I want to be able to "tune" this sensor essentially without interfereing with it too much.

    Can I just place a a second variable DC circuit in series? (I want to boost the signal between 200-350mV the original signal is about 1.45VDC)
     
  2. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
    9
    what TC is giving you 1.45v ??

    instrumentation diff op amp with gain needed and a pot on the output for tuning. this assumes small current requirements on the output stage, etc.
     
  3. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    It's been many years since I played with a Thermocouple but I would think the answer to your question is yes.
     
  4. Schutzengel

    Thread Starter New Member

    Jun 27, 2009
    2
    0

    that is more or less what I had assumed but you know what you do when you assume...

    TC with 1.45 volts is measuring the output of a sensor controlled heat generating device unfortunately use of alternate fuels vary the required output temperature for efficiency so I need to be able to "tune" the sensor to the correct the measurements, I wish I could go into more detail but I am still trying to put the system togehter in my head but I will let you know about the ideas when they have a little more solid footing.
     
  5. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
    9
    i dont follow.
    type k tc generates about 50.633mV at 1250°C, so i dont follow where this 1.45V is coming from.

    how accurate and how stable (ppm) does the solution need to be?
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Or do you just want a buffer amp with variable gain? We are curious about the very high output from a thermocouple.
     
  7. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Oops! I should have been more inquisitive about 1.45V output from a Thermocouple.

    This administration is looking for new alternative energy sources. If your TC puts out comparable current, I think you found it! :D
     
    Last edited: Jun 28, 2009
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