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I wanted to create a remote fired trigger for a spud gun so I can trigger it remotely.

Ideally I'd like to use a spark plug to fire because it should work well for gas mixtures but the trigger is pretty small/simple. Basically it's a a little remote box with a push button trigger that runs off of batteries.

It has a light, arm switch, and push button that triggers a relay but I currently don't have anything connected on the relay switch end.

Would it be possible to charge up some caps and get enough juice to bridge a spark plug with a small battery source (4 AAA or AA batteries) or would I need to step it up to something bigger (lipo or lead acid).

Note: I have used caps for filtering before but never for charging/discharging.

Update:

Just wanted to clarify. I know that a gas grill push-button igniter is a viable option but I'm looking for something more reliable. Ie, an igniter that I'm 100% positive it'll fire a good spark when I push the button. Check out "Tater gun Fires a Hunert yards" to see what I mean by unreliable.

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  • \$\begingroup\$ For anybody interested, I'm making progress on a breadboard. I'll try to diagram it and post some pics soon. \$\endgroup\$
    – Evan Plaice
    Commented Mar 23, 2011 at 19:50
  • \$\begingroup\$ You have to use a Coil, the battery outputs 12V and the 'plugs run on 11kV I think, you can get a cheap coil from a car parts shop, or Ebay/Halfords, they run on DC. They will provide a very good spark. \$\endgroup\$
    – Alex
    Commented Aug 9, 2016 at 9:03

7 Answers 7

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The answer for automotive spark plugs is no with a normal battery. But with a 9v battery by stepping up the current using a ignition coil (which ramps it up thousands of volts) then you will be able to use a spark plug....Only thing with that though is that your battery (9v) won't last long, as its "Juice" will be all gone in a few shots. Hope this made sense :) just tell me if not....

You could make a spark though with your normal everyday disposable camera....Something like this: http://www.angelfire.com/80s/sixmhz/camera.html

P.S: If you used a larger battery (more volts) then you would have more juice :)

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    \$\begingroup\$ Perfect sense... I was actually using the 4 batteries in series and a lawnmower spark plug to decrease the energy requirement. If you ever take a 9v battery apart it's nothing but 6 AAAA (yes, there is a AAAA battery classification) batteries hooked up in series. If needed, I could add 2 (or 4) more AA or AAA batteries in the series to up the voltage requirement. Any idea of how long it takes to let the caps charge, is there any easy way to tell (like, will an led hooked on the supply side lite up when the cap quits drawing power)? \$\endgroup\$
    – Evan Plaice
    Commented Mar 22, 2011 at 8:19
  • \$\begingroup\$ Well originally I use disposable camera circuits which generally come with a LED which turns on or brightens to its fullest when charged but you can check it with the resistance. I will have a look for you and see if there are any circuits on the net for you :) \$\endgroup\$
    – avitex
    Commented Mar 22, 2011 at 8:34
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    \$\begingroup\$ @EvanPlaice, if you use something designed for this like a 12V lead-acid battery you may have better results. \$\endgroup\$
    – Kortuk
    Commented Mar 22, 2011 at 9:18
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    \$\begingroup\$ @James 5 seconds is perfect. It's a spud gun not a gatling spud gun :). I'm trying to stick with 12v pack to keep it portable (ie, fit in a small project box). The LED design is interesting. I was thinking of a LED on the supply side to make it turn on when the cap is charged. IE, bridge a resistor in series with the led to ground so before the capacitor. So, the cap would be the path of least resistance while charging and become an open circuit when charged thus lighting the LED. I'm probably missing something here though. \$\endgroup\$
    – Evan Plaice
    Commented Mar 22, 2011 at 11:11
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    \$\begingroup\$ @James: What you're hearing is a switching boost converter that steps up the voltage to give the capacitor a high voltage charge. For a spark plug, you don't want to store lots of energy at high voltage, you just want to produce a high voltage momentarily. An ignition coil would be a better choice. \$\endgroup\$
    – endolith
    Commented Mar 22, 2011 at 13:46
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Capacitors themselves can't step up voltages beyond doubling or inverting, to do anything else you need inductors. As mentioned previously, automobiles use ignition coils, a transformer (inductors) in an autotransformer configuration like so:

enter image description here

Image from "How to use an Ignition Coil [in potato cannons]"

Another possibility, though there are some problems with it, would be to just open up a circuit with some large inductance in it, which will cause high voltages (and sparks) across high resistances (e.g. a spark gap). To do this, you'd need some switch that had a voltage rating much greater than your spark gap, which may be difficult to find.

From what I've heard though, pneumatic air cannons are much more controllable, and even better, they can be triggered using sprinkler valves which work at about 24 V (I use (3) 9 V batteries)

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    \$\begingroup\$ Ummm, the drawing is missing a capacitor. The guy who wrote the guide says it protects the breaker and may help enhance the spark a little. Read this mgaguru.com/mgtech/ignition/ig108.htm, the cap does more than help just a little. \$\endgroup\$
    – Evan Plaice
    Commented Mar 23, 2011 at 19:35
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    \$\begingroup\$ As the switch first starts to open, it will likely pull an arc before the spark plug fires. A switch which is designed for high voltages will quickly pull the gap wide enough that the magnetic energy stored in the coil will be able to go through the spark plug more easily than through the now-widened gap. If the switch doesn't pull a wide enough gap fast enough, most or all of the energy will go into making a spark within the switch rather than the spark plug. \$\endgroup\$
    – supercat
    Commented Mar 23, 2011 at 19:36
  • \$\begingroup\$ @supercat There are ways around that limitation. Basically, on the low side of the low voltage winding you use a n-channel mosfet paired with a capacitor bridging the drain to the source. That should protect the mosfet as well as prevent any sparks that may occur with the circuit is closed. Here's the resource I found to solve this issue. myelectricengine.com/everythingelse/ignition/ignition.html \$\endgroup\$
    – Evan Plaice
    Commented Mar 25, 2011 at 7:03
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    \$\begingroup\$ @Evan Plaice: My comment was in response to the question of why one needs a high-voltage switch. An inadequate switch will end up dissipating an substantial amount of energy in the form of contact arcing. This will both degrade the switch and waste energy which should be going into the spark plug. It's possible to use high-voltage electronics instead of a switch, but if the electronics aren't up to the task, the energy will go into destroying the electronics rather than sparking the plug. \$\endgroup\$
    – supercat
    Commented Mar 25, 2011 at 15:01
  • \$\begingroup\$ @supercat I'll assume that you didn't make the effort to read the article. The point I was making was, "high-voltage electronics" are completely unnecessary. The arcing problem can be easily solved by using a mosfet with a 'snubber'. en.wikipedia.org/wiki/Snubber explains what a snubber is. \$\endgroup\$
    – Evan Plaice
    Commented Mar 25, 2011 at 15:12
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Here's what I did, I put a spark plug in the end of the spud gun, disassembled a $10 ebay stun gun. soldered wires to the "legs" used the wire leads to the spark plug (one to casing ground metal and one to the end of the plug) push button and viola!! a few second spark!! most of these stun guns are rechargeable too so no carrying batterys!! One note of advice though prolonged use of the wire will cause burn spots and eventually lead to a short so use wire rated for spark plug use not some cheap speaker wire type stuff.

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We have a gas oven. That uses a piezoelectric crystal and a 1.5V battery to light a spark. It's not a spark plug per se, but perhaps you could use a similar setup.

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  • \$\begingroup\$ Can you link to one of these? I need something similar to ignite a small flame effect, but all the piezoelectric igniters I've found have a spring loaded button that taps the piezo material to create the spark. I need a ~5s continuous spark. \$\endgroup\$
    – Robert Atkins
    Commented Mar 22, 2011 at 15:51
  • \$\begingroup\$ @Robert Atkins, achieving a spark of sustained (5s) duration will be very difficult. Piezo is not the solution nor is an ignition transformer. You could look at a portable TV. The flyback in that puts out from 5 to 30kV and most run from 9V - 12V, that will put out a very large spark, but be very careful with this. It's unlikely to kill per se, as the current is very low, however, if you touch it, it will hurt very badly and you could burn or otherwise injure yourself. \$\endgroup\$
    – Thomas O
    Commented Mar 22, 2011 at 16:57
  • \$\begingroup\$ Hmm. If I said 1-2s would that make a difference? What duration is the spark from a motorbike ignition coil/spark plug? I need a compact, reliable circuit. \$\endgroup\$
    – Robert Atkins
    Commented Mar 26, 2011 at 18:42
  • \$\begingroup\$ @Robert Atkins, most of those sparks are sub 100 ms. It's very difficult to maintain said spark. \$\endgroup\$
    – Thomas O
    Commented Mar 27, 2011 at 20:55
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You can get electronics gas grill lighters. Look for replacement types.

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  • \$\begingroup\$ This is the route I'm actually trying to avoid. Gas grill lighters aren't very reliable. I wan't something that I'm 100% is giving a good spark when I push the button. \$\endgroup\$
    – Evan Plaice
    Commented Mar 23, 2011 at 8:27
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Maybe you could use onse of these: http://www.ebay.com/itm/Boost-High-voltage-Generator-DC-3-6V-to-40kV-Booster-Ignition-Coil-Power-Module-/231527277338?hash=item35e819e31a:g:cdcAAOSwqu9VIfeq

Edit: "high voltage generator power module 40 kv" is a good search term (if the link wouldn't work anymore)

40kV should generate a spark on the spark plug.

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  • \$\begingroup\$ Please include the referenced item in the answer. That link may not be valid for long. \$\endgroup\$
    – Icy
    Commented Nov 23, 2015 at 10:08
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https://www.sparkfun.com/products/11218 this link has a good and inexpensive option

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