Spark Fun (Fun with Spark Gap Igniter)
Duane Degn
Posts: 10,588
I purchased one of these a while back from SparkFun.
I thought I'd share some video of my playing around with the sparks it generates.
I keep calling it a "Spark Gap Generator" but it's really called a "Spark Gap Igniter".
I'm hoping a bug, which should be a better conductor than air, would trigger a spark between properly spaced wires and kill the bug. On our evening walds, my wife and I are often pestered by small flying bugs that seem to like to group together and fly in a small cloud over our heads. I'm hoping to make a "Wand of Death" to kill the bugs.
I'm not sure if I'd use such a wand even if it works since I'm not real eager to walk in a cloud of exploded bug parts.
I thought I'd share some video of my playing around with the sparks it generates.
I keep calling it a "Spark Gap Generator" but it's really called a "Spark Gap Igniter".
I'm hoping a bug, which should be a better conductor than air, would trigger a spark between properly spaced wires and kill the bug. On our evening walds, my wife and I are often pestered by small flying bugs that seem to like to group together and fly in a small cloud over our heads. I'm hoping to make a "Wand of Death" to kill the bugs.
I'm not sure if I'd use such a wand even if it works since I'm not real eager to walk in a cloud of exploded bug parts.
Comments
Seems this thing would make it pretty easy to build a Jacob's Ladder. Those are always neat come around Halloween time.
-- Gordon
Thanks for the heads up about the UV. I'll avoid staring at the sparks from now on.
I'm not surprised about the ozone. I thought I could smell it.
I tried a Jacob's Ladder without success. The spark does not travel up a pair of wires. The spark stays wherever the wire is closest together.
Coming in contact with something like that......would that be just a burn or worse?
Might try a thicker wire, like coat hanger. Use some steel wool to remove any varnish. Bend it so that there's a gradual V. The idea is that the spark produces a vacuum, and it's the vacuum that causes the slow ascent. It takes some effort to get just the right angle of the pieces. I don't see a reason why it wouldn't work.
-- Gordon
You'll need to find someone else to tell you.
I did have one unsparking wire touch my arm which caused a mild shock.
I'd imagine touching an arc would be painful.
The "wand of death" idea will work but you want a circuit more like a cow fence charger for that. A small electrolytic capacitor charged to 300-400 volts zaps them good. The hard part is getting 2 runs of wire close enough to zap them without having them short together. I threaded some 1/4" nylon rods to space the parallel wires and used them as the sides of a rectangular paddle.....more like a paddle of death in my case.
I think your right about the possiblity of these making a Jacob's Ladder.
I tried it again with two carbon fiber rods. I don't know if it's possible to get the distances correct using straight rods. I tended to either get a spark at the very bottom that wouldn't move upwards or to get a spark at the very top. I think the sharp cornered edge of the carbon fiber at the very top of the "ladder" caused the spark to jump at the top because of the shape rather than having the distance be the determining factor of where a spark started.
I think the bends at the top of a Jacob's Ladder is important to causing the spark to break.
I haven't tried a thicker wire yet. I don't think making a working Jacob's Ladder is important enough to me to get me to do all the work it would require.
I also have doubts that these spark gab igniters are very robust. I've read comments suggesting gaps of greater than 1/2" can severely shorten the life of these devices.
Thanks Kwinn.
I'm can see how my intial design has a serious flaw. I don't think these spark gap igniters are intended for prolonged "almost sparking" use.
I'll have to look through my caps to see if I have any that can take the voltages in the range you suggest.
http://www.ebay.com/itm/Neon-Sign-Transformer-6KV-30mA-No-GFCI-for-Tesla-Coil-and-Jacobs-Ladders-/251100876502?pt=BI_Circuit_Breakers_Transformers&hash=item3a76c74ed6
I don't think I want a Jacob's Ladder bad enough to mess with one of those transformers.
After reading more of the comments on the spark gap igniter product page, I think I've been pushing my luck by having the wires spaced as far apart as I had them in the video. Apparently these devices aren't meant to produce sparks greater than 1/2" in length. It would be nice if there were a datasheet for these things but no such luck.
1/2" sparks are nearly as impressive as the ones I was making. I'm pretty sure some of those arcs were longer than an inch.
Combining the 1/2" limitation with the vision hazard these things create, I think I'll stick with the device's intended purpose and use it to ignite flamable material. How boring.
http://www.amazon.com/Electric-Mosquito-Zapper-Swatter-Control/dp/B0053TROQQ/ref=sr_1_1?ie=UTF8&qid=1341805530&sr=8-1&keywords=bug+zapper+swatter
I was afraid someone would come along with a good idea like this and spoil all the fun.
Why would I want to buy two bug zappers for $22 when for a just a few times that amount, I could spend several days burning up electronic components, repeatedly shocking myself, permanently damaging my vision and, if I'm lucky, end up with a single device that only works half as well as the device available at Amazon?
for a device that sized there is NO vision issue .
a Weldor is 100s of amps. not mA or less of HV .. orders of magnitude less of a issue
assume 12V in at 500 mA and meh 6 kV the current is nothing to worry about for UV .
The spark gap in the 3rd photo that is used in the bottom of the base to switch the HV is seaing upwards of a KiloAmp of peak current It can be blinding as you can see in the photo.
How does 10 kVA of tranny look.. makes a Neon sign tranny look like a 9V.
this is at 12kVA or so in ..
as for a bug zapper .
* laughs*.
all HV is dangerious . but at the powers I play with it's instant death .
Slightly cheaper,
http://www.harborfreight.com/electronic-fly-swatter-40122.html
@Andrew, Thanks for the link. I'll probably give these "swatters" a try.
@Peter, Very cool stuff. I disagree about the "NO vision issue". The pain in my eyes I felt a few hours after making the video told me Gordon was correct about the eye danger.
The spark gap igniter was powered by 4V (a single LiPo cell) and I beleive it drew 3A (based on earlier tests with a bench top power supply).
@prof_braino, Those are cheaper. I wonder how well they work compared to the device Andrew linked to.
If any of you have experience with bug zappers, I'd be interested in hearing about it.
The bugs I'd like to get rid of are small. They're bigger than a fruit fly but smaller than normal flies; they're close to the size of a mosquito but they're not mosquitoes.
The bugs tend to gather just above us as we walk. My present theory is they're attracted to the moisture from our breath but I'm not sure why they follow us around. They generally don't land on us. I don't think they bite at all. They're just really annoying.
Sweet Home Alabama never disappoints: http://www.youtube.com/watch?v=bbLshnfu0wY
Peter! OMG! I heard there was a power outage in your neighborhood!
its not a issue . I own a spectrum analyzer and I have found out that Iam with in FCC limits .
.
also a TC is a horrid radiator at 100 KHz or so where it runs . the thing is one giant loading coil and a knarly Top cap hat ..
A Pen sized metal rod makes a better Broadcasting Antenna then this does at these Freqs
I have issues with it being loud !!!! 100+ dB !
As for the Police / fire .. why? its not any more dangerous then a BBQ ! .
I am not a Pro but I was mentored ( in the TC realm you cant teach this stuff ) by the worlds leader in HV FX
kVA FX . they are the ones whom did the termantor efx and tons of other millon dollar stunts .
you cant get a license for this stuff .. it does not exist . its not Pyro .. so that is out the window . its just HV .
the only issuse is that it is a fire danger again no more then a BBQ! but some dim whitted home owners insurance Co might not insure you if they have seen this thing fired up .
sorry not me .. they used Pad Mounts here not Pole Pigs .
Peter.
They're attracted to the CO2 we emit from our breath.
I'm going to answer the questions here so they can help more than just the one person who asked.
These igniter draw about 3 Amps of current so they need battery that can handle that much current.
Most of the LiPo batteries HobbyKing sells are made to power high current RC equipment so they are a good match to use with the igniter.
It's important that the igniter is powered with only a single LiPo cell. Two cells in series would burn out the unit. These igniters smell really bad when they get too much voltage (don't ask).
HobbyKing sells single cells but they don't come with a connector. Here's a cell that should power an igniter without trouble.
http://www.hobbyking.com/hobbyking/store/__18558__Turnigy_2200mAh_1S_20C_Lipoly_Single_Cell_.html
LiPo cells need a special charger. Parallax sells a charger that can charge just about anything.
I've used this cheap charger from HobbyKing. It works okay but doesn't provide any information about about the charge exept to indicate when it's done. This cheap charger only works with 2-cell and 3-cell packs.
I'm not sure what an inexpensive option is for charging a single cell. It might be easier to buy a 2-cell pack and only power the spark gap igniter from a single cell using the pack's charging jack (as I did in the video in post #1).
I have a couple of these 800mAh 2-cell packs to use with my quadcopter. One of the 800mAh cells should be able to power the spark gap igniter.
You can figure out how much current a battery pack can supply by multiplying it capacity and its "C" rating.
The 800mAh pack is rated 20C so it should be able to supply 16 Amps. I personally wouldn't feel comfortable using these batteries at 16 Amps for very long. The 3 Amps required by the spark gap igniter shouldn't be a problem for it.
I'll test the spark gap igniter with one of my 800mAh cells to make sure it works okay.
These battery testers erco told me about are great for getting a rough idea of the voltage levels of a battery pack. I'd suggest adding a couple to a HobbyKing order.
You don't want to discharge a LiPo cell lower than a certain amount. I think 3.3V is concidered safe but I usually don't let my packs fall below 3.6V or so.
Too high of a charge is also not good for a LiPo cell. I don't recall the exact level that's concidered too high. I'm pretty sure voltages above 4.2V per cell is too high.
While SparkFun sells a variety of LiPo batteries, the one's I looked at can't supply enough current for the spark gap igniters.
Matt
You are very welcome.
I tried the spark gap igniter with a single cell from 800mAh pack and it worked fine.
SparkFun sells a charger for single cell LiPos but it costs more than the two/three cell charger from HobbyKing.
While I think the prices from HobbyKing are great, they do take about three weeks to deliver the items unless you can find the item(s) in one of their local warehouses. Shipping is relatively expensive from HobbyKing so I try to buy a bunch of stuff from them at once. One of the things I often add to an order from HobbyKing is wire. I really like their silicon insulated wire. I also like their version of Dean's connectors.