Temperature Switch

Discussion in 'General Electronics Chat' started by vijaybala85, Apr 27, 2010.

  1. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    Can the LM341 5.0 be used for a temperature switch setup as shown? It seems to be working but the datasheet says minimum voltage it needs is 7.5V.

    I am supplying it an input so that the output is within 5V (as required by my DAQ card). The DAQ card itself has a 5V supply. So using that, I am basically supplying a 5V input to obtain a 5V output reg. Please let me know if I am clear with my question.

    Thanks!

    V
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    Do not believe it is possible to have a 5V regulated output from a 5V input. Is not your 5V supply already regulated? It would be possible to boost the input and then regulate the output. Some boost ckts also supply regulation.
     
  3. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    Thanks! All I want is the temperature switch to give an output 0V when temperature >50 deg C , otherwise give whatever input is supplied as output. So you think I can just use the series circuit without the LM341 and supply that as output to my DAQ?

    V
     
  4. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    how about this? My output should be within 5V because anything more than that would burn my card.

    V
     
  5. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    never mind!! I think I figured it out. And it is working
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Care to share what you did to solve the problem?
     
  7. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    Sure.... My need was to have an output of <5V because that is important for the device that reads it. So, I am not using the regulator but just using the second circuit that I showed. It is pretty simple and requires the non use of a regulator. My supply is USB powered and regulated.

    V
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    That's not so good, because when the switch opens, your input is floating.

    It should always have a path to ground; otherwise you may have odd results.

    ADC's also need a low impedance source for measuring voltage.

    This circuit addresses those concerns:

    [​IMG]
     
Loading...