Pilot Generator Voltage Doubler

Discussion in 'General Electronics Chat' started by hobbyvawt, May 14, 2011.

  1. hobbyvawt

    Thread Starter New Member

    May 14, 2011
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    My pool heater uses low voltage (>500mvDC). This low voltage comes from the pilot generator. My problem is that every year I have to install a new generator because I can only get 487-493mvDC out of the generators. I suspect that the heater is set up for a lower elevation. Anyway my solution is to simply double the voltage coming out of the generator. Any Ideas (simple ideas). My first thought is to use a N Channel MOSFET and a 1vDC AC adapter and run the pilot generator voltage to the gate of the mosfet thus switching on the 1vDC from the AC adapter, but I am open to other ideas. Please email me the respose as I might not be able to figure out how to get back to the page/site. Thanks
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Sorry, we don't communicate via Email, as that defeats the purpose of the Forums (sharing information) and creates a nightmarish situation for those who attempt to correspond with a number of people about their projects.

    On this page, click on the "Thread Tools" link, and "subscribe to this thread", so that you will be notified via E-mail when someone replies to this thread, and you will also get a link back to this thread.

    The phrase "pilot generator" seems to indicate a thermocouple attached to a gas-fired heater. Tampering with these controls could create a grave safety hazard.

    Your idea about using a MOSFET will not work; the threshold of the gate will likely be several volts. Besides that, one of the most common failure modes for MOSFETs is for them to become shorted; which would indicate to your valve that the pilot is lit when it may not be, resulting in a gas leak.

    I cannot recommend attempting to try a "do it yourself" solution, as you could very easily create an explosion hazard. I suggest that you contact the manufacturer of the heater in question to determine proper fault isolation procedure, and what are the correct components that should be used to repair any defects that you find. If you have any doubts, you should contact a professional pool heater repair service, as mistakes could result in a very hazardous situation.
     
  3. Jaguarjoe

    Active Member

    Apr 7, 2010
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    How about 2 thermocouples in series? You'll still be protected and get 2X the output.
     
  4. designnut

    Member

    Apr 21, 2011
    33
    1
    Try cleaning the pilot light tube to generate more heat, orr move the tube for greater heat.
     
  5. hobbyvawt

    Thread Starter New Member

    May 14, 2011
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    Thank you for your inputs. After considering the failure mode of the mosfet, I will not go that route.

    I live 30 miles outside of town and Ive had two pool guys show up, they both installed pilot generators and both only worked for a few weeks. They start out generating 700mv then slowly go down. Ive also replaced all of the other components include control board.

    I will try using 2ea pilot generators in series.

    Ive heard of using a couple of NPN transistors to boost the voltage but have not found a schemtac that I can build from but Ill keep looking.

    I only need a 100mv boost
     
    Last edited: May 15, 2011
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    951
    How does the wiring connect? Sounds like a connection issue. A thermocouple output voltage does not degrade so significantly in so short a time, but copper can become oxidized quickly at high tempertures. Verify the connection methods used and then examine the connections for corrosion(discoloring indicates oxidation of the copper)
     
  7. BillB3857

    Senior Member

    Feb 28, 2009
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    Do the old generators have a heavy soot build up on them? If so, it will act as an insulator. Make sure you have a nice blue flame hitting the generator (thermocouple).
     
  8. hobbyvawt

    Thread Starter New Member

    May 14, 2011
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    Connections - I have cleaned all of the connectors as well as replaced all of the temp and pressure switches.

    Flame - Is a nice blue color and the tip of the generator is in contact with the flame.

    Soot - No soot present
     
  9. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
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    The generator is no acting as the flame sensor is it?

    If not, then there is no safety issue involved.

    How about a small solar cell that uses the light from the flame to give you the 500mv?

    That should be pretty darn stable once at temp.
     
  10. BillB3857

    Senior Member

    Feb 28, 2009
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    If only the extreme tip is in contact with the flame, try moving it so more of the body is in contact with the flame.
     
  11. hobbyvawt

    Thread Starter New Member

    May 14, 2011
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    The Pilot Generator is a safety device that does not allow the main gas valve to open without an operation pilot flame
     
  12. hobbyvawt

    Thread Starter New Member

    May 14, 2011
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    I think I will make a few changes on the pilot flame by closing off the unused backside and repositioning the generator
     
  13. BillB3857

    Senior Member

    Feb 28, 2009
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    Unused backside ??????????????
     
  14. hobbyvawt

    Thread Starter New Member

    May 14, 2011
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    The pilot flame is kinda weird...It has a center disk and comes out in a circle
     
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