Weber Bug Zapper questions

Discussion in 'The Projects Forum' started by rc10mike, Jul 17, 2014.

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  1. rc10mike

    Thread Starter New Member

    Jul 17, 2014
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    So I recently picked up a working Weber bug zapper. Im just looking for your guys help to learn more about it, and to possibly do some upgrades. I took some pics of the circuit. It looks EXTREMELY basic compared to my newer zapper. From my limited knowledge:

    120v input splits to a regular florescent ballast, and to a HV transformer. Theres a safety switch wired in also.

    Theres what appears to be a capacitor of some sort wired directly to the HV outputs. This is what Im curious about.

    What exactly is this cap there for?
    Cap looks like it has 15kv printed on it, but why 15kv when the grid is 5kv?

    What effect (if any) would upgrading to a larger 15kv cap (if it is in fact a cap) have on the performance of the zap?

    Thanks for any help.
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  2. inwo

    Well-Known Member

    Nov 7, 2013
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    In general a small capacitor across transformer improves regulation.

    In this case it could be to protect transformer from HV transients.

    Or possibly improve performance during bug events.

    Lets see what the gurus say.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I'm not a HV guru but my thoughts is that the cap can provide a higher peak current (to explode the bug) than the transformer HV secondary which will have a lot of resistance and be poor at supplying high peak current.

    So the transformer raises the voltage as the AC rises, then it gets to the voltage where it can arc through the bug, then at that point the cap supplies a decent chunk of energy and enough peak current to explode the bug and clear the short circuit.

    Without the cap it might just keep fizzling through the bug with low current every cycle, and that will short out the zapper mesh.
     
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  4. rc10mike

    Thread Starter New Member

    Jul 17, 2014
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    So, can I just use any bigger capacity 15kv cap to "Upgrade" the zap?
     
  5. wayneh

    Expert

    Sep 9, 2010
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    Doubt it. The cap was sized to work with the rest of the circuit. It's not likely the limiting factor. Otherwise they would have spent a few cents more and built a better zapper in the first place.
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Maybe it's still worth a try? It might give some gain. It depends on the impedance of the transformer(s) and if it can charge that cap high enough each cycle. Being AC it needs to charge it and discharge it every cycle.

    A slightly larger cap might be ok, (20% larger??) but if the cap is too large it won't have time to charge to a high enough voltage and all you are really doing is lowering the voltage.
     
  7. rc10mike

    Thread Starter New Member

    Jul 17, 2014
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    So from the pics, what do you think this capacitor is rated?

    I couldnt find anything on what the 750M means.
     
  8. wayneh

    Expert

    Sep 9, 2010
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    Yeah, it's probably a cheap experiment and maybe the cap has degraded over time anyway so that a fresh one might help. Not much to lose by testing.

    I predict that the transformer is the most costly component is normally the limiting component.
     
  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Most likely matches the modern code for 75 pF, although sometimes old stuff has marking directly in pF so it might also be 750 pF.

    Since there is a 10x difference, googling some photos of 14kV ceramic caps in both sizes should make it pretty obvious from which one it looks like.
     
  10. rc10mike

    Thread Starter New Member

    Jul 17, 2014
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    Today I did some experimentation with the output cap. I received a few 15kv 4700pf in the mail.

    WOW what a difference the cap makes!!

    With the 4700pf cap installed, the zap is extremely loud, I would say its at least 3x as loud to the ear.

    I did try reinstalling the original cap just for verification purposes.

    Next upgrade is the transformer. I have a 5kv 30ma neon sign transformer on the way.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    Very interesting, good work. Proved my theory wrong! It won't be the last time.

    Is there a reason you want to make such a powerful zapper? I mean, if it does the job now, will it really do a better job after the upgrades? Are you zapping sparrows?
     
  12. Sensacell

    Well-Known Member

    Jun 19, 2012
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    Is it possible there is a HV rectifier hidden in there some place?

    Then the cap would be the primary energy storage device.
     
  13. rc10mike

    Thread Starter New Member

    Jul 17, 2014
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    Well, it worked great for a day....
    [​IMG]

    So what would cause this cap to fail?

    Bugs were super active tonight, then it got quiet....I noticed smoke coming from the top.

    Its a 15kv cap so I wasnt expecting this!
     
  14. rc10mike

    Thread Starter New Member

    Jul 17, 2014
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    Actually I have fond memories of messing with bugs and zappers when I was a kid. The current all plastic ones just arent the same...
     
  15. debe

    Well-Known Member

    Sep 21, 2010
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    Should be an AC rated capacitor as these units are AC not DC.
     
  16. debe

    Well-Known Member

    Sep 21, 2010
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    Thaught id check one out that's similar, the 2 capacitors are disc ceramic HV. They weren't maked with a value but they read 2.8Nf to gether. As you can see it does pack a fair spark & its continuous across that gap. This thing realy does destroy flies & bugs. If you go for a Neon T/F & the voltage is too high you may have problems with contious arcing across the grid.
     
  17. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I think it is time to close the thread before anyone gets hurt.
    I am closing this thread as it violates AAC policy and/or safety issues.

    Quote:
    6. Restricted topics.

    The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

    • Any kind of over-unity devices and systems
    • Automotive modifications
    • Devices designed to electrocute or shock another person
    • LEDs to mains
    • Phone jammers
    • Rail guns and high-energy projectile devices
    • Transformer-less power supplies
    This comes from our Tos:
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    Bertus
     
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