DC to AC inverter help

Discussion in 'Power Electronics' started by mbdesigner, Jul 3, 2017.

  1. mbdesigner

    Thread Starter New Member

    Jul 3, 2017
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    I'm wanting to drive a 30Watt UV actinic fluorescent tube from a 12V battery for a moth trap. It's for attracting moths into a trap where they can be identified and released again unharmed.

    The electronics I'm planning on using for this include a standard T8 ballast which is designed to run from 240V AC and an inverter.

    To make life easy I was looking at inverter modules on eBay and found quite a few like this:

    http://www.ebay.co.uk/itm/Hot-150W-...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

    The specification of this states that it is a high frequency inverter @ 20KHhz!!! Given that my ballast would normally expect to run from a 50Hz supply, is this thing going to be suitable?

    I apologise if this is a very silly question, but my field is in digital electronics!

    Thanks
     
  2. crutschow

    Expert

    Mar 14, 2008
    19,545
    5,447
    No, that will not work for your purposes. Note this statement:
    upload_2017-7-3_9-15-18.png
    You need one that will output 220Vac @ 50Hz, perhaps like one of these.
     
  3. tcmtech

    Distinguished Member

    Nov 4, 2013
    2,809
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    You could just use a off the shelf unit. It would be far more efficient and likely cheaper as well.

    https://www.powerstream.com/ballast-1.htm ~$25 - $35

    That or build the actual 12 volt ballast circuit. They are pretty simple and dozens of variations of them are easily found online.
     
  4. mbdesigner

    Thread Starter New Member

    Jul 3, 2017
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    Thanks for the fast replies. I've pretty much exhausted the off the shelf 12V ballast options. I'm based in the UK and I can't find anyone who supplies them; LED lights are the thing now. UV actinic lights however are preferred for me as they actually give off a very nice range of the UV spectrum whereas LEDs give off a very narrow wavelength.

    Anyway the inverter boards above look good now I know to stick to 50Hz.

    These looks like they need a step up transformer:

    http://www.ebay.co.uk/itm/12V-24V-t...hash=item43f8dae2f0:m:mRJq79V9ulPdS9wGGfo3dug
     
  5. crutschow

    Expert

    Mar 14, 2008
    19,545
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    Correct.
    You can use a 220V to 12V transformer and run it it reverse.

    That's why they are cheap, they don't include the required output transformer. :rolleyes:
     
  6. mbdesigner

    Thread Starter New Member

    Jul 3, 2017
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    I am however interested in the point about the use of a 12v ballast circuit would be more efficient than my idea of using an inverter and 240V ballast. Is it going to make a really big difference? A more efficient circuit potentially means a lighter battery which makes all the difference when carrying your equipment to remote locations.

    I could consider making a circuit if it will make a big difference.
     
  7. ian field

    AAC Fanatic!

    Oct 27, 2012
    6,172
    1,115
    You don't need sinewave if you drive the tube directly, there are plenty of tube drivers around, but the flyback type blacken one end.

    You get around 20% more light at 20kHz.

    If you go DIY - I think you need a Royer inverter.
     
  8. tcmtech

    Distinguished Member

    Nov 4, 2013
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    I don't follow how that works being I live in the middle of nowhere USA and I can get anyting mail order from anywhere in the world being most major online parts places ship worldwide to any point modern/civilized enough to have internet without a second thought.

    Figure that for small power inverters and low frequency ballasts ~80 - 85% efficiency per stage would be a reasonable value to calculate around which would give you a realistic working efficiency of ~65 - 75% to which when running on batteries every percent of efficiency gains helps.

    Whereas a dedicated high frequency solid state 12 volt ballast might run at 90 - 95% efficiency.
     
  9. FierceGuineaPig

    Member

    Mar 14, 2017
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