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Description: These transformers are capable of creating spark gaps up to about half-an-inch. They work really well as an ignition source for things like potato cannons, they also make the official sound of the mad scientist. The sparks that are generated sound a lot like a taser and you should take that sound as a warning to take extreme care when the unit is powered.

To throw sparks, simply secure the blue and grey wires to electrodes spaced no more than half-an-inch apart and connect the red and white leads to a 5V source. Be warned, these transformers draw about 3A so your power supply will need to be somewhat robust.

Note: We are now carrying a new model of this Spark Gap Igniter, it has the same specs as our previous one, it just looks a little different. The dimensions of the center barrel are 71 x 21 x 25mm and the overall length with the wires is 350mm. 

Note: Please do not use these to shock people or animals. Seriously, that isn't cool. Actually, be extremely careful with these as they can seriously hurt you. If you don't fully understand high voltage, just live vicariously through the video.

Dimensions:

  • 71 x 21 x 25mm Center Barrel
  • 350mm Overall Length

Features:

  • Input Voltage: 4.8V (works fine at 5V)
  • Current Draw: 3A
  • Spark Gap: <0.5"
  • Loud and scary
  • Full of wonderful

Comments 225 comments

  • It’s shocking the amount of puns already in these comments.

  • Full of “Spark FUN”!

  • Loud you say? I wonder if you could modulate the voltage around 5v and get some audio out of this thing? Guess I’ll need to try it out…

  • So mine arrived yesterday.

    Output starts at appx 1V, and I didn’t go beyond 5V on the input. Current demand (as expected) is very spiky, you’ll want a 1000uF or so cap on the input leads unless your supply is very beefy. Mine was hitting the 3A limit at about 3V.

    Breakdown voltage in air is a pretty vague idea of output because it depends greatly on electrode shape and dimensions, humidity, air pressure… It also would only indicate peak voltage.

    I didn’t have anything handy to measure that high a voltage, but a 1.5M 1/4W resistor was overheated pretty badly (light smoke) which leads me to believe that the sustained output is about 1200V at 800uA That’s probably correct within a factor of 2.

    There’s a significant amount of high frequency current on the output as well, a 0.03uF 3kV cap reduced the apparent output quite a bit, and got fairly warm even with only 2V input to the module. It may have been breaking down internally, or it may have been conducting HF current. Attaching either lead to a short neon tube (8") lit the tube in my hand, so that confirms a pretty high AC component on the output. I did have a 10kV cap handy, but I decided not to charge that up with the supply as I didn’t have a safe discharger handy.

    Tonight, I’ll try a measurement with my high voltage probe, which is a 1Gohm HV resistor.

    My best guess at this point, is a royer converter feeding a Cockroft Walton voltage multiplier, similar to low power He-Ne Laser tube supplies. These may well have been designed for that purpose. High striking voltage, and lower sustained voltage/current.

    • Mine starts up below 1.5V, and will deliver about a ¼" spark with a single AA Cell as input. I was busy last night and didn’t get to make more measurements.

      • Finally got to do the measurements. Load was an HV 1090Mohm resistor, into my 1Mohm scope input Grey lead +, blue lead connected to scope ground.

        Input Output 1.0 3V 2.0 8V 3.0 11V 4.0 16V 5.0 20V 21800V under 1.09Gohm load

      • I got mine today and hooked it up to a computer PSU, but i could only get

      • That’s awesome, thanks. I’ll just have to wait until mine arrives and I can do my own testing. ;)

    • Current was 3A at 3V? It will operate as low as 3V? If so, I suspect one should be able to operate it nicely on 3 D cells, but probably best with that capacitor you suggest.

      Edit: Nevermind. On further reading, looks like Ds (alkaline at least) shouldn’t go much beyond 1 amp.

  • It seems very interesting, but what would actually happen IF you got stun by this?

    I’m not exactly known for being too cautious when playing with high voltage stuff at the workbench. And I do have felt some stings due to this.

    • In order to produce a spark over a gap of approximately 0.5 inches, these things must have an output of thousands or even tens of thousands of volts (depending on atmospheric conditions like humdity and air pressure). Of course, the output current is going to be very small, given the total power of ~15W (Power = Voltage * Current, and without factoring in real world losses Input Power = Output Power). However, that combination of high voltage and very low current is still enough to cause significant pain, electrical burns down through the skin, involuntary muscle contractions, and possibably even permenant localized nerve damage on the extremities (for effects on the torso, see below).

      When dealing with voltages ~100V or greater, I would never under any circumstances allow an accidental circuit to form across someone’s upper torso (e.g. never make contact with a live wire with one hand and a ground with the other). With voltages this high a continous current can be forced through the skin (which actually is somewhat electrically insulative) into the rest of the body (which appart from bone, is much more conductive). There are several important organs in the chest cavity that are very electrically sensitive, including the heart and the diaphram under the lungs. These vital organs can be disrupted and/or damaged even by very low currents (e.g. less than 0.1A can stop a human heart, just 1mA can force the heart to beat irregularly, and if your diaphram is paralyzed it’s very hard to breath).

      That said, it only takes a relatively small amount of care and foresight to work safely with parts like these. For example, make sure to remove power from the circuit it is on when working on or near that circuit, that the insulation on any wires or other connections are completely entact and protected from accidental damage, etc… Really, it’s mostly the basic stuff you should do when working on electrical circuits in general. The only difference is the consquences are more severe if you neglect to take precautions and something goes wrong.

      • Firstly, thanks so much for taking the time to write this informative text! Nothing I would have expected in a comment section on a site - but hey, this is Sparkfun which never stops amaze me ;P

        I fully understand your points, for instance I do my best to work with one hand/one limb when working with “feelable” voltage to avoid just what you said. And currents crossing the torso is what I would try to avoid the most.

        Just to make it clear; my intentions is not to use this on a living organism, but as I’ve already said I tend to be a bit clumsy from time to time so I -should- consider it as being accidentally stun sometime(s) if I were to play with this. But your answer was calming, hopefully I would make good use of it :D

        And yes, I will grade the pain from 0 to 10.

  • Chock full of subpoena potential.

  • After a month of continous use the unit is working great. Created a small solar charged battery powered electic fence charger. Used a 3.3 volt Sparkfun Arduino Pro mini with a FET soldered direct to pin 3 and ground running the blink led sketch. Solar panel keeps the 6 ah Lipo battery charged. This will not power miles of fence but works great for spot applications.

    Cows ate all the wires off my trailers so ran a small loop of electric fence around it and no more problems. Has high voltage but low amps. Hurts but does not seem to injure cows or people (me).

  • To make your display operate as you intended, common connect all intersect electrodes, add 2 additional electrodes to the midpoint of each segment fed via 1 Meg 2 Watt Carbon resistors.(Carbon due to the historical behavior of Metal film resistors suffering from arc bypass under high voltage transients.) The resistors will allow for arcs to form to both end electrodes in a given segment, as well as extend the arc event time, also reducing radiated EMI due to lower arc current. Experimentally determine the maximum forward input voltage that can be applied without triggering an arc discharge cycle with the module fed via a MR755 or equivelant diode. This is to get the internal HV supply in the CDI module near to but not in excess of the firing point. By use of a second supply, (5VDC), supplying high side drivers controlled by the Uno and outputting to the segment’s CDI unit downstream of the MR755. Drive the segment @5V only long enough for one discharge event. Sequentially strobe the segments in a round robin fashion to minimize overal power dissipation.

  • Im not sure what to take of this. Who wants to make a potato cannon!

    • I’m making an automatic potato cannon with a USB/joystick interface with some gear motors.

  • Does anyone know the max voltage input it can handle..? Ive seen videos where people are using 6 to 9v..

  • Hot damn these are fun to play with! They’re not kidding around when they say they’re filled with awesomesauce; these things really wake you up in the morning! They work very well given a ¼" gap and two C-cell batteries. Will post more info when I can stop being entertained like a child…

  • WARNING!! I’ve read concerns about the arc these devices create. Apparently the arc can produce shortwave UV light that is very damaging to ones eyesight.

    Edit: The concerns are valid. After making the following YouTube video, my eyes hurt a lot from looking at the arc too long.

    http://www.youtube.com/watch?v=f16ysxIqWJI&feature=relmfu

    More information about using a LiPo to drive these igniters may be found here:

    http://forums.parallax.com/showthread.php?141163-Spark-Fun-(Fun-with-Spark-Gap-Igniter)

  • One of my spark gap is dead !! I never put the voltage above 4.2V, I did 3 times quick connect-disconnect to see spark at wider gap. What happened here ? Time to break open this dead one.

    • Hey Hary, when you tear it down I’d love to see pictures! Lots and super macro mode :-)

    • If you went over a half-inch, it overloaded itself. I think these ramp up the voltage between the sparking electrodes until breakedown, which discharges it, and then it starts again. It’s extremely fast, hence the buzz. If the gap is too wide, the voltage goes over what it can handle, and it kills itself, like an LED without a current limiting resistor.

  • I’m thinking an Arduino interface, an antenna, and a coherer interfaced to another Arduino and we can give the Xbee a run for it’s money.

  • Does sparkfun sell a voltage regulator that will drop a 7.4V lipo down to 5V that can handle 3A?

  • Oh - and is there a capacitor in there, just waiting to surprise me after I’ve removed external power? Should there be a bleeder resistor across the output lines?

    You know what I say about bleeder resistors - better the resistor than me…

    • I know what you mean - I’ve been bitten by the capacitors in tube laser supplies which had been unplugged for weeks. That’s the sort of lesson you learn very fast.

      This is not authoritative, since we haven’t depotted one yet, but I’m guessing that there is no significant capacitance on the output. I’m basing that on the fact that Robert and Nick were messing around with their 7-segment display moments after cutting power to the modules, without any swearing or 911 calls that I could hear. I’ll verify this with them, but as with all HV supplies, always treat it as if it might be hot, handle wires with one hand, etc. Be careful and have fun.

      • I just got a shock from one that was not powered. Not a big shock, but still.

  • Yet again, SparkFun makes my current project suddenly obsolete! And I just got the email from BatchPCB saying my boards were shipped. My project is a CRT power supply, and it looks like I could just hook a capacitor and diode to one of these to come up with a good many kilovolts. A simple feedback loop would let me pulse the ignitor to maintain a desired voltage. MAYBE. I’ll have to give it a try.

  • I wonder if you could connect 10 of these, 5 per side and make a lightning gun…hmm

    • What you describe would be something that makes a lot of flashing light and zapping sounds. In otherwords great as prop for an amatuer Sci-Fi film or a fun project to show-off at a Maker Faire, but not functional energy weapon.;) Like I indicated in another comment, it takes thousands of volts to cause a spark over the ~0.5 in these things work on and would take something capable of hundereds of thousands of volts for a functional range of longer than a foot.

      Of course, if you want create a real lightning gun it is technically possible. It would require a sufficiently ionized small continous pathway in the air, thus dramatically decreasing the voltage required for an electric discharge from the gun to the target. This would be similar to how tiny plasma channels enable natural lightning discharges. One way under investigation, electrolaser, would be to use a laser beam to create the pathway. Unfortunately (or prehaps fortunately;)), the type of lasers Sparkfun sells are far too underpowered to create an adequate plamsa channel.

    • pics or it didn’t happen :-)

  • Nifty. Can’t tell if this will cause a continuous spark or if it’s for a one-off pulse. Might be good for making a jacob’s ladder if it’s continuous. Any data sheet available?

    • No data sheet (sorry), but it is continuous. And loud.

      • The noise it makes tells me that this is not continuous but a very rapid pulse. Having pulled apart a similar device before (from a cheap Chinese “taser” torch) there is probably a small spark gap inside it which feeds the actual transformer inside the HV end. A continuous AC arc would hum at it’s frequency with out the “snapping” sound and a continuous DC arc just hisses.

        • For the benefit of the OP, I was differentiating it from the single spark that a piezo igniter or xenon flashlamp produces. But you are correct about the theory of operation.

    • check the video tomorrow, we run it through its paces.

  • I bought one of the originals, It runs just fine on a single 18650 Lithium Ion Cell (3.7volts) and creates a spark of about 15mm, noisy too and a bit scary.

  • Anyone know where to get a cheap 4/5 V battery?

  • I got it .. it is awesome :)

    but the gap spark is not too big at 5 v or even 9 volt how ever i tried it at 12 v WAS WOOOOOOW but stopped working after that :D

    so what u recommend 5 or 9 or ?

  • well anything tat has Features of “Loud and scary and Full of wonderful” clearly needs to be bought. This thing is AWESOME!! What is it useful for? Other than a way overkill ignition for a potato cannon, pretty much nothing, but you should still own at least 6. WARNING: I did accidentally shock my hand with this: my arm was numb and twitching for at least 5 minutes, and still tingled for way longer. This thing is dangerous, use with caution.

    • Sheesh! Hope you are ok! We like loud and scary and full of wonderful, as long as there isn’t bodily harm involved :)

  • So I’ve built a potato gun… go figure. And want to upgrade my ignition system. This product looks perfect. The electrode I want to use is here: http://www.thebbqdepot.com/replacement-ceramic-ignitor-electrode-4309.html The actual ‘trigger’ will be a spring loaded push button for a quick spark, and I’ll be adding a toggle switch to prevent premature combustion. The only thing i need to work out is the power source. Would the 4xAA barrel sold on this site be sufficient? Too much? Too little? And how fast would the batteries drain? Also, the entire set up should fit inside a 3" Sch 40 PVC tube. Thanks for your help and FYI, I’m very competent but am still new to this game so please don’t get crazy with the vernacular. Also, the accelerant is Suave Max Hold hair spray. I’ve lobbied Suave to change the name to “Max Range”. I’m putting spud out there well over 300 yards.

    • Sounds like a great project! We’d love to see pics of it. We actually built something similar that you can see here.

    • It can be powered by a single AA battery. 4xAA is going to deliver 6V, which is more than it’s rated for. I’d go with 2xAA.

  • Question: Is it possible to get these to emit a single spark at a time? Perhaps with a timing circuit or something? I’m thinking of trying to use one to record impulse responses for convolution reverb. Seems like this would be (only slightly) less scary than using something like a marx generator. Which also would be difficult to create a single spark with, and I’d have to worry about discharging caps.

  • Mine died already, just used it a few times 4.5volts and always less than .5 inch gap

  • Help. I’ve burned out two of these in 2 days. The gap is just about exactly 0.5". The input voltage is 5v and about 5A is available. It cycles on for 10 seconds or less and off again for 5 seconds. More than 4 cycles in a row is very rare. I’ve used them in installations like this one before with success, but suddenly there are problem.

    I’m wondering if there are severe restrictions on the length of the wire between the SGI and the spark. It’s about 6' I’m wondering if capacitance on the output line is a problem; the wires are close together and at one point run through a few inches of brass tube.

    At $15 per experiment I don’t want to do a lot of experimenting. I need insight, quickly, or I have to find a way to generate the spark differently.

  • This thing is awesome! It did however scare my dog so much he is still shaking 20 minutes later, and my wrist still hurts from the shock. Be careful, these could do some serious damage.

  • HELP NEEDED.

    These are neat little devices but they are a pain to operate. They want 5v at 3A, and my design runs on 12v. A voltage regulator like LM1084IT-5 works, but even with a good sized heat sink it gets hot enough to boil off water, and since the device is only rated to 125C, I’m probably at the maximum limit for the device, and I do not want that.

    What I really want is not to have to convert voltage at all. I’d rather run the spark at, say, 12v and 2A. Thsi device can’t handle that, but if someone has a schematic for this thing, I’m assuming it could be scaled up. Has anyone opened one up? C'mon, people, share. It’s a nice device but it is not quite right for long term, portable use.

  • Can someone answer this question: How many time per sec does this fire, or is it continuous? How long after you apply 5V does it take to fire? Do the ends of the bare wire get eroded away after some time? Thanks!

    • It fires up in under 100ms, but I haven’t timed it precisely. From the sound, it’s probably sparking at over 50Hz but to the eye it looks continuous. The frequency varies a little in operation and also varies depending on air humidity.

      Any metal will erode away eventually under this treatment, but I’ve had fine results with brass.

  • I’ve bought 3 of these, but before I received them I discovered some commercially made electronic BBQ (gas cooker) igniters in my local hardware store. These operate off a single AAA or AA battery (depending on whether it is a two output of a four output model). The dual output AAA battery model will create a reliable 0.5 inch pulsed spark. With the built-in press switch and battery holder they are perfect for my orange cannon project, and reliably ignite an AeroStart (ether based diesel starter) mixture. Now, what am I going to use my 3 Spark Gap Igniters for?

  • I’m looking to use this on the wild thumper chassis like the scorpion, and I was wondering exactly what you used to power and control it.

  • I just received this device today and wooooooow it is as they say it is if I could put a video up I would thank you Spark Fun.

  • These things are pretty awesome.. I hooked it up to 3 D cells and got a nice pulsed arc at nearly ¾ inch. although anything more kinda spreads the charge through the glove (dont ask!)I had attached it to (DO NOT RECOMMEND AS IT DOES GIVE A FAIRLY HIGH TINGLE WITHOUT EXTRA INSULATION!). At a smaller distance it gives a higher frequency arc which is good as I wanted to use it as a replacement to the ignitor for my gas cooker!

  • This may be shocking what I have just found–(in reply to the video) Make the wires to make the segments of equal polarity when next to each other. This means that when two wires to make the segments are near each other, make the wires the same polarity so they don’t zap each other.

  • Tried reading the comments, has anyone been successful in getting it to light a propane or butane gas? I am using it in an arduino project that will remotely light a flame.

  • I just got this product for Christmas today and I only got it to work a few times running on an arduino UNO r3 and my pc now It just makes a buzzing noise can someone help me

  • I purchased this product an I’ve had it for about 3 hours and I only got it to work the first few Times running off an arduino UNO r3 and my pc does anyone have a solution

  • I made a short video demostrating a few fun uses of this product, including further destroying a defective SSD, creating aluminium confetti from a CD, and lighting up a LED in entirely the wrong way. These things are way too much fun.

    http://youtu.be/zrT_wuig-eU

  • These would be better if they had a supply voltage of 12 volts @ (say) 1.2 amps rather than the strange 4.8 volts at a large amperage.

    If these items are custom made for Sparkfun, you may sell more if the next batch came as 12 volt units.

  • my original one is indeed defective, i think it was an instability in my power supply and spiked outside it;s rage. i will try to rip it apart with epoxy remover to atlest see the output transformer, the others i have work great and from my experience in hv i would say an output of over 10kv is easy, i want to see if the can be put in parell but would need to be dc first and phasing is unknown. anyway very impressing for the size. I have a 5ma 30kv supply and it’s arc is not as impressive. anyway time to order more for fun! if i find anything interesting on dismantling the bad one i will let you know

    • Don’t do it! sparkfun will send you a new one if you contact them and get a replacement shipped out for free!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  • OK simple and maby i got a defective one, but correct me if i am wrong but positive is red and negative is white, some how mine failed, draws 6 amps and no output and it’s only a few weeks old. maby some one messed with my lab supply or not but i ordered 2 more for kicks and giggles but this time i will have a diode reversed biased on the input to protect the device. also the output seems to be ac, i have a high voltage probe and will try to calculate the voltage later is another does not beat me to it

  • numitron driver? no, better yet, mini CNC plasma cutter! or micro stick welder?

    • This doesn’t generate enough Amp to produce any significant amount of heat, use a Microwave oven transformer instead (Danger Danger Danger!)

  • I was reading comment and it appear this need to generate a spark all the time, i.e. it cannot be left open with only the HV floating, is that correct? I want to use it to replace the flyback transformer I use to protect a very expensive drone from being stolen. So far i’m using a flyback transformer from a 7inch CRT TV but it generate a lot of RF and EM noise, consume a lot of power and the output being few million volt is way to powerful and dangerous, I don’t want to kill people I just want to make sure no one steel my drone, this would be perfect as its similar in power than those inoffensive BBQ igniter… would a spark gap protect the transformer while leaving any voltage in-between the spark occurrence floating? i.e. is the output ramping until the spark occur?

    • I’d suggest an old fashioned lock and chain to make sure “no one steel my drone” (whatever that is). Killing someone with a booby trap (even accidentally) will most likely land you in jail. It’s hard to pursue your hobbies in jail. Just sayin'.

      • Yeah this is definitely too dangerous, I tried it and will never touch it again… I was somehow thinking this was similar to BBQ igniter (harmless and fun to shok people with), but this is to make tazer gun… Btw, my idea was to protect the drone while it was moving in the neighborhood and electro-shock activated remotely only if someone pick it up but i’ll find something less powerful, maybe a strident noise like they use in ship to repel pirate hehe, (product idea SF!!)

  • anyone know if you could do a plasma like speaker with this?

  • If you only need one to fire, wouldnt you be able to connect it directly to the arduino and code it appropriately? Something like when a switch is pushed run this motor but its actually the ignitor. would this work or no?

  • Im working on a potatoe gun prodject where I need to get a spark to set off in 4 different barrels in a sequency are there any relays that are rated for the output voltage of the spark or anything that i can channel the spark or will i have to buy 4 different spark transformers ?

    • The easiest (but not the cheapest) way to do this would be to use four separate transformers. Because the spark can jump a gap of at least half an inch, a normal relay (which has a gap of a 10th of an inch at most) wouldn’t be able to stop the spark.

      But you could try to make some sort of crazy high-voltage relay yourself, with a motor or other mechanism making the connection, maybe even a rotary platform that moves the transformer source against wires to your four barrels in sequence. Whatever you do, be careful and send us pictures!

  • Having unbelievable problems with the 2 of these I bought. They work fine unless they are near other components. Either they induce enough EMF or RMI to screw up the circuit I built to control them; or currents running near them screw them up. The upshot is that if it’s packed into the case near other components and wires, the spark fails in a few milliseconds (there’s a single spark, then silence), but if it’s away from everything else, it runs for the full few seconds I give it power. Wrapping it in foil has not helped.

    So I’m posting this as a warning - if you use it as part of a complex circuit, prototype with the SGI nestled right in with your circuit components. I have over $150 invested in a steampunk gun project, that looks to be a total failure because of this.

    If I find a solution I will post again.

    • In the end, I got a working solution by having the SGI far away from other components. It’s not a great solution - it means running the SGI;s output through long, carefully shielded wires to get the spark where it needs to be - but it worked in the end.

      To repeat the warning - when you prototype, making sure your physical layout matches the final construction, so you’ll be able to tell if the noisy field this thing puts out is a problem or not. It’s a great spark generator but you may need a lot of shielding to use it with anything else.

  • Well, I’ve read a comment on here that says this wont ignite a gas. Can anyone confirm this? Has anyone tested this? I would like to try to ignite butane. Would that be possible?

    Thanks, Matt

  • Does anyone know what the diameter of of the spark gap module is?

    Thanks Matt

  • could you drive these with a single short, high-current dc pulse, i.e., from a cap or cap bank? if so, how short of a pulse? i’d prefer to not blow out my batteries every time i need to shoot a potato at something :D

  • Hm, I wonder if this would be useful for a (slow?) EDM machine. Has anyone tried to erode metal with the spark?

  • It worked for about 2 minutes and then overheated and stopped. It hasn’t come back yet. Fortunately I ordered two, but at 5V it is probably not designed for continuous use.

    Does anyone know which bue/grey is + and which is - (think negative ion generator)?

    It is humid today that may be why I’m getting sparks of over an inch.

    • hum, odd. we used ours continuous at 5v for a LONG time (as seen in the video) and they still work fine.

      • My power supply might have been at 5.1 or 5.2 volts. I can try repeating the experiment at 4.8 using a variable switcher. In any case something inside was getting hot after a minute or so. Also I wasn’t letting the sparks discharge - I was trying to see if I could do ions or something more like static electricity.

        • Several people have reported that putting the generator in a position where it can’t discharge lets out the blue smoke (see above). That’s more likely to be the problem than the supply voltage.

  • is the input ac or dc? is the output ac or dc? thanks

  • someone take a dead one and put it on the band-saw…

  • looks like there needs to be a way to limit the current these guys can draw out of batteries… I used an old ignition coil out of a car for a project and you will find that they are filled with oil to dissipate heat and they also have a big wire/ceramic resistor that is used with them… if I had one I would put it on by bench supply and set the C.C. mode to a more conservative value…

    • I just got two of these and started playing with them. One thing I noticed is that if I run it off of a D-Cell battery at 1.5V, it produces a short, rapidly repeating spark. BUT, if the leads are too far apart, they don’t kill themselves.

      I think running these at 4.8V is overly optimistic. You can do that, but you run the risk of killing your unit. Besides that, just how big of a gap do you need to ignite a gas or other combustible? If people want to play with high voltage sparks, there are other websites out there that specialize in that subject. I don’t think these are made for that kind of experimentation. A furnace ignition transformer is a lot more fun if that’s what you’re after, but you can’t run those too long continuously.

  • Hey Spark-fun… or anyone that has one do me a fave…. Get a clear burned out, non working, light bulb and see if you get any plasma with these? I used a broken plasma globe driver to do this … http://on.fb.me/NzDBF7 and got some really cool effects… just be warned if you do this to stay away from the metal base of the blub and use and old fashioned ceramic light blub socket to prevent “oh hell” face…

    • looks like there needs to be a way to limit the current these guys can draw out of batteries… I used an old ignition coil out of a car for a project and you will find that they are filled with oil to dissipate heat and they also have a big wire/ceramic resistor that is used with them… if I had one I would put it on by bench supply and set the C.C. mode to a more conservative value…

  • hurley_108, thanks. Let’s make Taser gun but I heard it is illegal to have it without license (but make it such that ?). Hmm.. how about “don’t touch me jacket” with conductive thread SF sell here…

    I just found out: this device can create legal issue in MI : 750.224a Portable device or weapon directing electrical current, impulse, wave, or beam; sale or possession prohibited; exceptions; use of electro-muscular disruption technology; violation; penalty; definitions

  • After scaring the crap out of my dog and deeming this thing needed to be put away (for now), the damn thing gave me a pretty good, I’d say 5x static shock as far as pain factor. Do be careful and always discharge, don’t be an idiot like me :P

    • Can it still spark after you disconnect the power?

      • some of these that we tested held a bit of a charge and needed to be discharged after power was taken away, but I found this one to not act like that. once power is disconnected, there doesn’t seem to be much of any residual charge. but you can easily use a piece of metal (insulated screwdriver?) to discharge is as a good practice.

  • This is my new favorite thing ever!

  • TRYING TO MAKE A SPARK OF MORE THAN A HALF INCH CAN KILL THESE DEVICES!

    Sorry to yell, but I think this is a point which is not adequately made in the product description or the comments to date. I killed mine inside of a half hour playing with the spark gap, accidentally making it too big.

    Without a datasheet or even a schematic of a similar circuit, my supposition (based on comments) is that the input end is a coil of wire, and this will burn out eventually with too much voltage and therefore too much current, but may be tolerant for a short time. On the output (sparky) end, the circuit build up voltage until the air breaks down and arcs. There may be an internal capacitor or something to store charge until the spark, but if it is prevented from sparking by a too-large gap, it will ramp up the voltage beyond its own capabilities and it will kill itself, probably within one or two multiples of the (very short given the pitch of the noise) spark-to-spark time.

    Unless someone can show me where I’m wrong (and I’m very open to that), I think that these are very capable of overloading themselves if they are not allowed to spark due to a too-large gap.

    • Sadly, I think this is very true. I had two kill themselves after playing with them for around 15 minutes max. I don’t think I will drop anymore money on these until there is some more information. Although it is fun making large gaps, I think this kills them in the long run. Just take caution with large gaps..

      • Could you hacksaw one of the dead ones into sections and see what’s inside? (especially capacitors…)

    • Can anybody confirm this?

  • Here’s a video of one running off 3xAA batteries. The batteries were putting out 4V with no load. I just touched the wires to the batteries while I was recording which is probably why it starts/stops.

    http://www.youtube.com/watch?v=kQN3Xys1Ilc

    The gap is 14mm…which is over half an inch! I assume you can do even better than that with 5V and more amps.

    PS: I don’t think this is a good way to do it for more than a few seconds - the batteries are overloaded and bad things will happen.

  • Mine just arrived. You can get a continuous stream of sparks from a single AA battery. It seems to be pulsed internally…anybody know what’s inside that block of resin?

  • Mine arrived today. A D-cell will make an arc of ~2-3mm, so no disagreement from what’s been reported here by others getting it to turn on with one alkaline battery. I also have a 6600mAh, 3.7V LiPo pack, which makes a nice arc of ~10mm.

  • I bought two of these and they quit working after a week about a day from each other. I have tried different power supplies and everything else one can think of. They don’t even make the hissing noise anymore. Anyone else have problems with these?

  • I have three questions: - Just insecure about this from the description: do you feed it with a continous 5V, or do you pulse switch it in order to get sparks? - Would this light up the xenon flash tube from a disposable camera just with the SGI? - Is it relatively shock resistant? If you were to put on a small cross motorcycle for the ignition system? Thanks :)

    • I tried lighting up a xenon tube I had lying around, about 8 inches long, and that immediately killed the device.

    • I can answer that first one: no, you just hook it up to ~4.8V DC. I’ve been using it with 3x C batteries. They started out at a total of around 4.89V and now they’re down to about 4.68 volts.

  • Mine came today. I ran them (one at a time) off a power supply that’s rated at 5v, 3A. (My test meter claims the voltage is more like 4.6v, but it’s a cheap meter.)

    Both units behaved well. The arcing makes a LOUD noise, probably 80db/1m or more, with a frequency that depends on the distance between the wires. The spark’s reach is over ½", sometimes nearly 1"; but it’s a humid day. If too far apart, you get an intermittent spark; further apart again and there’s just a vague hissing.

    I want to thank the guy that ran his at 6.6v - I was considering using a 6v battery, and his note saved me from cooking my unit. That does tell me, though, that these things are probably designed close to the absolute voltage limits, and will probably fail sooner or later under normal use.

    It’s fun to make the spark travel around corners, with glass tubing. The spark is a bright, solid white, and much “fatter” than I expected. The spark color doesn’t seem affected by the metal of the electrodes (I tried sparking through copper and brass), and the surface of the brass electrodes was ablated only very slightly after ten seconds of sparking. (That said… any electrode is eventually going to get cooked away, so design accordingly.)

    I haven’t tried this, but putting the voltage through the right two pins of a large vaccuum tube (DON’T pick the pins for the tube heater!) might product some fascinating, lightning-in-a-glass-bottle effects. If someone tries it (carefully, please), and it’s pretty, let me know.

    • http://on.fb.me/NzDBF7 get a dead clear light bulb and try and let me know, I used an old plasma globe driver ….

    • Be cautious running high voltage through a vacuum tube. You’ll be generating x-rays.

    • I’m also pleased to announce that a picaxe and a 200 ohm resistor have no trouble driving the gate of the MOSFET advertised on this page, and the MOSFET itself has no trouble handling the current needs of the SGI. I think it’s safe to say that this isn’t going to lead anywhere wholesome, but it’s going to lead there quickly.

  • When I apply 5v to this I get a “whine”, but no spark. No spark no matter how close I put the electrodes.

    Any idea what might cause this?

    • These take quite a few amps to ignite. You might check the voltage on your 5V supply while you’re trying to run the sparkler; if the voltage drops significantly, you’ll need a beefier supply. If your supply stays at a solid 5V, you might have gotten a defective unit (sorry about that!). Contact techsupport and we’ll help you out.

  • Oh no! The igniter on my propane grill just fizzled out, guess I’ll just have to use this :)

    • If you’re serious about the grill, this product would be a more practical and easier to implement replacement. For starters (pun intended), it doesn’t need an external power supply. Unfortunately, as of this posting it is out of stock, but backorder is allowed.

      • I wanted to go with this one because it looks awesome, and is “full of wonderful.” But also because the current igniter is also a piezo igniter which don’t work well at high altitudes (I’m at 8100 ft). Even when my current igniter worked it took a few pushes for it to actually spark.

  • All, I tried the Jacob’s ladder thing as well with brass rods and it did not fly for me either, the arc stayed around the closest point. That said, a cautionary word on the input voltage rating. I was using a 2S LiFe battery (2100mAh 20C) that provides nominally around 6.6V. I never let the circuit run more than 2 seconds at a time with most pulses around 1 second or less. I was demonstrating today that spreading the gap much beyond the .5 inch point causes the circuit to not spark and that was it… the unit quit working. No more spark with even < .5" gap. Fortunately I bought two :) cuz this kind of stuff happens to me all the time. By the way, no magic smoke, not even the slightest satisfying hint of fried trons. Guess that potting stuff is really good. So, now to figure out how to dissect this thing without destroying it beyond recognition. Any suggestions?

    • A Jacob’s ladder rerquires a continuous lf AC arc, it climbs the ladder due to thermal effects of the air the arc is discharging in.

    • Immerse the carcass in a mixture of Methyl-Ethyl-Keytone and GP laquer thinner. Cover container tightly and wait. I about 2 days the epoxy will begin to swell and soften. Keep picking off the softened compound and returning the device to the bath. I estimate in about 7-9 days the module’s innards will be 90% clear of potting compound. I use the same method for depotting Ford Electronic ignition modules for repair.

  • Can someone try a quick and dirty Jacob’s ladder and see if it works? Coat-hanger wire (would the lacquer be an issue?) or ?

    http://deskarati.com/2012/02/03/the-physics-behind-the-jacobs-ladder/

  • Well I managed to fry two of these… I thought I could get away with wiring them in series using 12V. They ran for a few seconds and then will no longer work…. Well it was fun while it lasted.

    I would have thought two in series would pull about 6V each. I did have them hooked to a 25AMP powersupply and maybe at that voltage they were able to pull too much current.

    I think I will have to order a few more, they are too much fun not to have around to scare people with.

  • I just received mine today and it is loud. I need about 10 more of these. Lol

  • Oh, and for those of you who have played with one already - I’ve got a concern about the draw on these things. I have a 5v power supply that provides 5A. That 5A is going to (intermittently) run Mr. Spark Gap Igniter, a few LEDs and an Arduino. I’m afraid the voltage drop Mr SGI causes when it fires up, is going to starve the arduino of power.

    I can put a serial diode and parallel cap between the battery and the arduino, but there will be voltage drop from the diode and I don’t know how well the arduino will react. Anyone have experience with this? The other option is a diode and a cap on MR SGI - but I’m worried it would have to be a freaking huge cap, which I may not have room for. Suggestions welcome.

  • I’ve ordered, but I didn’t realize how slow SurePost would be. (Lesson learned.) I need to know the physical dimensions of this thing, so I can plan my enclosure layout. Can someone measure diameter and length, down to the mm? Very much appreciated.

  • What happens to them at 6v? I want to run one off a 6v battery, with a MOSFET between, and I don’t expect much voltage drop from the MOSFET. Do I need to get a 5A diode in there for more voltage drop?

  • No replacement for a proper data sheet, but I know air has a breakdown voltage of something like 3kV/mm - ½ inch is about 12.7 mm and 12.7 * 3000 = 38100V. Impressive!

  • I “request” a carveup of this thing. it looks potted.. but you guys are creative. (hint: heat works wonders on that crap)

    • I’ve never found heat to work. it just destroys everything inside too… it’s pretty solid. I doubt we could get inside easily.

  • I’ve bought one and I’m just wondering what the risks are, if anyone knows, of accidental shorts between the blue and grey wires, or leaving it powered without it being able to spark for periods on the order of minutes. Thanks!

  • Lets say one were to use one of these near an Ionic pro…

    What would happen?

  • Notice how short the wires are? So your guaranteed to be right next to the drapes while playing with it! LOL

  • A potential solution to the seven segment display thingy would be to use some corona dope. It may help and it may not help at all. Just an idea.

  • Portable rail gun charger…that could work…

  • Finally, SparkFun is starting to sell parts I can use to really hurt myself!

    • I wouldn’t worry about those. They say ‘healthy’ right on them. ;)

      • Safety note: Combining the igniter and the pads would be a very BAD idea :p Just sayin'… I may have to order one of these and measure the high voltage output, verify its switchng frequency, add in a voltage multiplier…make a beam on target neutron gun to activate a sub-critical pile…Hey, kids, let’s make a desktop nuclear reactor! That shold DEFINATELY win the science fair…or else…:p

    • They’ve been selling these for almost a year now.:p

    • clearly you havent seen the Solid state relay breakout board page.

      (im joking)

  • Fantastic! I could use this with my brewing controller to turn on a flame.

  • Do these work in reverse? ie: take a high dc voltage and drop it down to 5v. If not, what would I use to do that?

    • If these things really are based on ignition coils (which I think is most likely), they wouldn’t be able to work in reverse. A normal step-down transformer would be able to do what you want. Sparkfun doesn’t have a large selection of component transformers (i.e. just a transformer, not sold as part of anything else), so you might have to look elsewhere.

      • Great I’ll look for some, thanks!

        • Oh and just be sure you know what order of mangitude the input voltage will be, that’s going to greatly impact your design. Transformers by nature of their construction have a set ratio that they will change the voltage. This ratio is based on difference between the number of loops (or windings) between the two coils that constitute the transformer. Also if you can’t find a single transformer that will decrease the voltage enough in one step, you can use different transformers (even ones with different ratios) in series.

          Finally, don’t forget about Ohm’s Law! I don’t know what you mean by “high voltage”. However, bringing hundreds or thousands of volts down to 5V means you will end-up with significant current gains, even factoring in the energy lost by going through one or more transformers. If you started out with more than micro Amps on your high voltage input, you’ll need to seriously consider how your 5V side of your circuit will safely deal with the resulting low voltage but relatively high current.

          • Well I guess I misspoke(typed) when I said high voltage, I’m just looking to control a 110V DC LED rope light with an arduino. I had no idea of the magnitude of this thing’s output! So even though it’s not “high voltage” would I still use a step down transformer to control it or something else? All mosfets and relays that I’ve looked at have max voltage ratings of 60V DC or so. Thanks for all your help!

            • I come from an electrical engineering background. There’s no real binding consensus among EEs about exactly the threshold for “high voltage” is, but many would consider anything above a few hundred volts to be resonable.

              Also, Sgt_Lemming’s suggestion on finding appropriately rated MOSFETs will a much better solution for what you are trying to do.

            • if you want to control something that is 110vDC (which is a weird voltage, are you certain it’s not AC?) then you will probably need to look at one of the bigger parts suppliers for mosfet rated that high. They do come at that voltage and much higher to boot. I have some 1200v rated ones here.

              • Thanks I’ll take a look at digikey! Yeah the LEDs in the rope light are wired in series so the its at 110V DC but only 20mA which makes it really difficult for me to control.

  • By the way, the output voltage can be estimated because insluating materials (including air) all have dieletric breakdown voltages (AKA the dielectric strength of a material). Which is basically a measurement of how much voltage is required to create an electrical discharge through a given length of material. This value can vary a lot in air, but is normally between 4 KV/cm to 30 KV/cm. So measure how far you can set the wires apart as still reliably achieve a spark and you’ll have at least some idea how large the output voltage is for these things.

  • I’m trying to think of a good portable power source for these. I have lots of high capacity LiPos, do you know if these would work with about 4V from a single cell? Would two cells destroy it?

    If no one answers, I’ll answer myself in a few days when I receive my order.

    • I used one of these with a single LiPo cell and it worked fine. Here’s a post about my experience. Post with video

      I was obviously creating sparks across a gap greater than ½" but from now on I’ll limit the gap to ½"

      I believe the other warnings about large gaps killing these devices.

      The LiPo I used was a 5,000mAh 20C cell.

    • If you have LiPos to spare I can see how you might want find-out yourself. However, I’d be less concerned about what the voltage of two LiPo cells would do to the igniter than what the igniter’s high current draw (nominally 3 Amps) might do to the batteries! These igniters probably use specialized form of transformer called an ignition coil. If so while there might be a few passive components, like resistors, at the core (pun intended) these things would be coils of copper wire.

      Personally, I would use a 6V lead acid battery with an appropriate discharge rating. Sure, sealed lead acid batteries aren’t as small and “sexy” as LiPos, but they would be a more reliable (and probably safer) solution.

      • These LiPos are made to power “coils of copper” wire (RC motors). I have a bunch of 5Ah packs rated 20C or better. They should be able to handle 100 Amps. I don’t think 3 Amps will be unsafe in the least.

        • Sounds ok to me, but you didn’t specify the type of LiPos available in your initial comment.:p The capacity and discharge rate of LiPos can vary greatly! Just look at what’s available through Sparkfun, some are 1Ah but only 2C others have a discharge rate higher than 30C. On the other hand, almost any commonly available 6V SLAs would have sufficient capacity and discharge rate to use without major problems, even for someone reading this that was a complete electronics novice.

          So please forgive me when, lacking complete information on what you had available, I tried to give you (and potentially others) advice that would ensure you would avoid problems. Problems that at best would ruin your batteries and at worst cause injury and significant property damage.:)

          • I may forgive in a day or two :)

            I did say “high capacity LiPos” in my intial post.

      • I burnt mine out using a 6V power supply. Wouldn’t recommend it.

        • A single cell LiPo will power these igniters just fine.

          http://www.youtube.com/watch?v=f16ysxIqWJI

  • Wow, this looks fantastic to make a 5V tesla coil. Next project..

  • I’m thinking this would be great to drive the primary of a Tesla coil.

  • Can these be used to ignite fireworks?

    • tape a match to the fuse. I bet this guy could light a match. Did something similar in physics class in high school. Had to make a potato cannon but had to be 10 ft away when fired. Tried a rocket engine igniter but it didn’t do the job until we taped a match to one.

    • I’m not 100% sure. Probably not. They work best with gasses. You might be able to light gunpowder or something like that, but I wouldn’t rely on it to light a fuse. BUT, try it out?

      • What about a fuse dipped in gasoline?

      • It’s always nice when someone encourages you to play with fireworks and high voltages…. you go ahead member#218980, DO TRY THIS AT HOME.

        • Well it seems to me that RobertC. was encouraging experimentation with using this product to light a fuse. Fuses don’t have to be connected to fireworks or anything else explosive. So RobertC. wasn’t necessarily encouraging anything potentially unsafe.;)

          • Objection! …missleading the Jury!

            ….The counselor is providing his own interpretation of the issue in question.

            The defendant clearly indicated the use of the questionable product as a viable way to char or reduce the amount of extremities in the victims hand.

            • Overrulled, on the grounds that I kinda want to see the results in a video…

              • Having played with something similar here before, it won’t light a sparkler. It simply does not have enough amperage to generate the required heat. As for a fuse I think it would depend on the composition of the fuse but I am dubious for the same reason as the sparkler.

                10KVAC @ 1A however will happily light a sparkler.

                http://www.youtube.com/watch?v=6-fxEZ3xgP8

        • just be safe or something like that…

  • I’m guessing you need to drive these with 5A AC. Any idea what frequency is best to use with them?

  • Wondering what is inside…

    • magic.

    • Awesomesauce.

    • Sgt_Lemming answered that question here:

      The noise it makes tells me that this is not continuous but a very rapid pulse. Having pulled apart a similar device before (from a cheap Chinese “taser” torch) there is probably a small spark gap inside it which feeds the actual transformer inside the HV end. A continuous AC arc would hum at it’s frequency with out the “snapping” sound and a continuous DC arc just hisses.

  • “full of wonderful” Err ‘full of wonder’?


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