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Project: Fluoro Lamp Power Inverter (12v)

Discussion in 'Electronic Projects' started by hsab, Mar 23, 2005.

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  1. hsab

    hsab New Member

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    hi for all members.

    no comment :roll:
     

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  2. williB

    williB New Member

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    hi hsab,
    what does it do..?
     
  3. hsab

    hsab New Member

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    hi

    this sheme works with 12v batteries

    we can use it at home when light cut off; in vehicule to repair wheel inthe dark far way home........................

    i build it and it works ok .

    by
     
  4. dave

    Dave New Member

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  5. drrogla

    drrogla New Member

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    what does this circut draw from the power suply (i.e. car battery)?
    and how powerful can the fluorescent be?
     
  6. hsab

    hsab New Member

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    hi

    use 12 v batteries

    power lamp fluo from 18watts to 36 watts

    @+
     
  7. satishkikani

    satishkikani New Member

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    nice

    this is nice[/i][/b]
     
  8. stanleycarl2

    stanleycarl2 New Member

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    Hello,
    how are u doing today?iam stanley from Nigeria.iam a student,i need ur help.I was told in school to present a project topic for my final year.I need ur help ok.
    my email address is stanleycarl2@yahoo.com
    i will like us to communicate via my email address cos i have time checking it everyday.
    thankz
    stanley
     
  9. etes_oroq

    etes_oroq New Member

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    Hi hsab:

    hope you're having a nice day today.

    We had a similar project way back in my college days. Just want to ask if the it's possible to use a 1/2-inch (12.5mm) diameter AM radio antenna ferrite rod instead of the "philips tv psu ferrite" used in this project ?

    By the way, I'm from the Philippines, so i have to find the JIS (Japanese) equivalents of BC series transistors. That I can google my way from here.

    jun balista [etes_oroq]
     
  10. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Why did your lights get cut off? Did you forget to pay your electricity bill?
     
  11. Rolf

    Rolf Member

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    This is OLD technology, it is much more efficient to use the battery power to drive LED's directly. If I remember correctly, white high efficiency LED's produce around 130 lumen per watt versus about 80 for fluorescents.
     
  12. Hero999

    Hero999 Banned

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    Flourescent are more efficient than LEDs, well for producing white light anyway.

    The problem with this circuit it it drives the tube of pulsed DC not AC so it won't be as birght and it won't last as long. You need a push-pull driver and centre tapped transformer primary to get an AC output and drive the lamp properly.
     
  13. fonze

    fonze New Member

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    Found this one haven't tried it yet, I am in the proces of building it.
     
  14. Hero999

    Hero999 Banned

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  15. Oznog

    Oznog Active Member

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    The output of the transformer shown is still AC! However that type of drive is indeed inefficient and makes poor use of the magnetic core. The output may be a bit "spikey" too.

    Rolf, what Hero999 says is accurate- good flourescents are more efficient than LEDs.

    Starting and driving a flourescent is a bit tricky, and requirements vary from tube to tube. Of particular interest is that the impedance of the tube changes as it ages or just warms up. A fixed voltage may either not be enough to drive the tube with enough current OR it will provide the tube with too much current. I'm not big on home-grown solutions myself because it's such a complicated task to do right.
     
  16. Hero999

    Hero999 Banned

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    I believe we've seen this discussion on this forum before. The transformer's primary is driven by one transistor connected to a positive supply. When the transistor shuts off the back-emf generate by the field around the primary collapsing induces a large negitive pulse in the secondary, this repeates continiously. Hence it is generating pulsed DC not AC. The pulses travel in one direction only, from the cathode to the anode causing the catode to be brighter and excess electrode sputter around it, this isn't good. One solution to this problem is to simply add a capacitor in series with the tube, this will effectively block the DC level (remember pulsed DC is simply an AC voltage plus half it's peak value DC offset).

    True, because the pulses are only one polarity the same is true for the field, in effect only half the magnetising potential of the core is being used.

    That's an understatement, there's a heave peek at the start of each pulse followed by ringing (which may be damped when the tube ignites).

    To date this is correct, but while fluorescent tube technology is mature LEDs are continuing to improve, it's only a matter of time before they beat fluorescents.

    It starts off open circuit before ignition and drops one struck, then continiues to drop as the current increases until either there's no more gas to ionise or the wiring resistance or fuse limits the current.

    A constant current source is idea but this is normally approximated by a large inductor, at mains frequencies, or with a high frequency inverter a capacitor can be used (which will also solve the pulsed DC problem). Often the transformer is specially designed to have a very high leakage inductance to limit the current, this is true bot for some mains ballasts and inverters.
     
  17. Oznog

    Oznog Active Member

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    Certainly not. No transformer can ever create DC without a rectifier, no matter what you do with the primary.

    Current in induced in the secondary winding when the mag flux changes. The mag flux increases when the primary transistor is on and creates current in the secondary. When the transistor is off, it decreases and makes current in the other direction. The sum of current over time must always be zero. The shape of the waveform is typically undesirable- when the transistor is on, flux increases rapidly making a high current spike on the output. Then it decreases at a more moderate rate when the transistor is off.

    However, the core flux is always in the same direction. It increases and decreases but does not reverse, so the core is essentially biased at all times like an electromagnet. This reduces the capacity of the core. Furthermore, if you do not allow enough time for the flux to be drained by the load during the "off" period, current will increase even higher the next "on" period and so on until the core flux reaches a saturation point. At that time the current during the "on" period is limited only by the total resistance in the primary circuit and will typically draw enough current to smoke.

    It is not a very appropriate design. He needs a split primary pretty badly.
     
  18. Hero999

    Hero999 Banned

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    Alright I'll be a bit more acurate doesn't create steady DC, it makes very small positive pulses and very large negitive pulses.

    Try connecting the primary of a small mains transformer to an AA battey in series with a switch, connect a neon lamp to the secondary. When you hold the button the neon might flash very dimly as the field builds but it will flash even brighter when you release the button as the field collapses and notice the corrona is only generated around one electrode.


    True but not much current is generated as the field builds slowly.

    When the transistor suddenly shuts off, the current in the primary decay more rapidly and generates a huge back EMF, it explains why you can generate 1kV from a 1:20 transformer with only 12V at the primary.

    You've got that the wrong way round, the current increases slowly when the transistor turns on, remember inductors don't like sudden change in current and it's for this reason that a huge spike is generated when the transistor turns of; it's like turning a relay off.

    That's true in this case and it's why large negitive spikes are generated.

    It does turn off (minus the small current in the feedback).

    No, it's because the core is only ever being magnetised with one polarity.

    That will only happen if the tube is disconnected.



    Either way I agree.

    But it does use pulsed DC, read the link I posted before. I've bought cheep DC fluorescent tube fittings before and one end of the tube always goes black and it doesn't illuminate uniformly
     
    Last edited: Aug 15, 2006
  19. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    There's too much rubbish on these forums about 'pulsed DC', there's not really any such thing - it's AC, as simple as that!.

    The reason one end blackens is because the AC used isn't symmetrical, nothing to do with 'pulsed DC'. It's simply because the inverters used are crude, and waveshape isn't of much concern.
     
  20. Oznog

    Oznog Active Member

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    Running a tube with too little current will also blacken the ends in short order. I assume doing it with too much current will do the same thing.

    Waveforms which heavily deviate from a sine wave are a problem, but so is failure to regulate tube current. IIRC those great compact flourescents actually require a bit of starting cycle algorithm to get long life. Take one apart sometime, the 110v ones- even the cheap ones- still have like two dozen components inside.

    There are some quality 12V DC devices out there:
    http://www.oksolar.com/n_cart/search.asp?cat=Lighting&subcat=Fixtures%2012VDC
    And these are some excellent 12v DC lamp bulbs. They're really good. I've used them.
    http://www.oksolar.com/n_cart/search.asp?cat=Lighting&subcat=Light%20Bulbs

    They're certainly expensive for a flourescent, but those are not the "crude" solutions mentioned.

    The simple answer is to simply use a power inverter.
     
  21. Hero999

    Hero999 Banned

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    I did explain this a couple of posts a go.

    None the less you do have a point, but how else should I explain it?

    How about this:?

    This inverter is no good because the AC waveform it produces is very asymmetrical (mostly negitive). Current only flows in one direction through the tube the electrons are only emitted from one end of the tube, this causes one end to be brighter than the other and excess electrode splutter also occurs at one end cause it to go black.
     
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