Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 75 users online :: 3 registered, 0 hidden and 72 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Ignition system help!

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Ignition system help!

Unread postAuthor: Spudgun on Crack » Thu Apr 24, 2008 3:14 pm

Is it possible to use a flyback transformer and a camera circuit to make a spark.

I read the wiki on the ignition coil and the camera circuit and how you can discharge it into a coil to produce a spark.

I would hook a camera flash circuit up to a coil on the flyback and then discharge it, but would this produce a large arc?

I am not concerned as to if it harms the flyback (I have a bunch) but I need to make an ignition system out of parts that i already have.
  • 0


Spudgun on Crack
Corporal
Corporal
 
Posts: 79
Joined: Sat Jun 23, 2007 4:43 pm
Reputation: 0

Unread postAuthor: SpudFarm » Thu Apr 24, 2008 3:16 pm

use just the coil and the camera
  • 0

"Made in France"
- A spud gun insurance.
User avatar
SpudFarm
Donating Member
Donating Member
 
Posts: 2563
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area
Reputation: 0

Unread postAuthor: Spudgun on Crack » Thu Apr 24, 2008 3:30 pm

What do you mean just the coil and the camera?

Do you mean hook up the camera without a capacitor to the coil?

I thought about that but I don't know if it works or not.
  • 0


Spudgun on Crack
Corporal
Corporal
 
Posts: 79
Joined: Sat Jun 23, 2007 4:43 pm
Reputation: 0

Unread postAuthor: psycix » Thu Apr 24, 2008 4:23 pm

Use it with the following things:
Flyback circuit
Capacitor
Coil

Use the flyback to charge the cap, and then dump the cap trough the coil.
A high voltage spark will be generated.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: Spudgun on Crack » Thu Apr 24, 2008 5:13 pm

I got the flyback to make a spark, it was not very big (1in or less)

that was with 3 capacitors in series for a total of about 1000v and then i discharger it through the coil but it is not that big.

Any ideas why? I mean 12v can make a huge arc so why can't 1000v make a huge arc for a second?
  • 0


Spudgun on Crack
Corporal
Corporal
 
Posts: 79
Joined: Sat Jun 23, 2007 4:43 pm
Reputation: 0

Unread postAuthor: TurboSuper » Thu Apr 24, 2008 6:17 pm

You connect the capacitor of the camera flash to the coil through a switch of some kind. That way, it discharges a 200V-300V pulse with a healthy amount of current through a step-up so you get a nice arc.

Anything more than that is just overkill, really.
  • 0

"If at first you dont succeed, then skydiving is not for you" - Darwin Awards

TurboSuper
Brigadier General
Brigadier General
 
Posts: 986
Joined: Thu Jun 16, 2005 1:44 pm
Reputation: 0

Unread postAuthor: DYI » Thu Apr 24, 2008 8:12 pm

You won't get a spark much longer than 1.25" from a standard ignition coil, as it'll start arcing through the internal insulation of the coil. If you need impressively high voltages, you'll either need to make your own step up coil with better insulation, or make a Marx generator, either of which would only be moderately difficult.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Sponsored

Sponsor
 


Unread postAuthor: JDP12 » Thu Apr 24, 2008 9:27 pm

look on the wiki they have an article about it I believe
  • 0

"Some say his pet elephant is pink, and that he has no understanding of "PG rated forum". All we know is, he's called JSR. "
User avatar
JDP12
Major General
Major General
 
Posts: 1943
Joined: Fri Mar 30, 2007 8:34 pm
Reputation: 0

Unread postAuthor: jimmy101 » Fri Apr 25, 2008 2:34 pm

Spudgun on Crack wrote:I got the flyback to make a spark, it was not very big (1in or less)

that was with 3 capacitors in series for a total of about 1000v and then i discharger it through the coil but it is not that big.

Any ideas why? I mean 12v can make a huge arc so why can't 1000v make a huge arc for a second?


The power into the coil controls the power out of the coil. Power is not just a function of the input voltage. It is the input voltage times the input current. A 12V car type battery can supply ~300 amps (or more) at 12V. That's 3.6KW. A 120VAC wall outlet is usually limited to 15 Amps, so it can only supply about 1.8KW. The car battery, even though it is lower voltage, supplies twice as much power as the wall outlet.

Coils, transfomers and the like are even more complex than the simple power equation suggests. The rate of current rise and fall controls the output voltage. Furthermore, transformers are generally designed for a particular current rise/fall rate. Get to far away from the desinged rate and the transformers efficience drops way off. Flybacks are generally designed to be operated at either 25KHz or 50 KHz (IIRC). Get too far away from that and the don't work nearly as well.


More importantly than all the stuff above, why would you want a bigger and/or more powerful spark? You don't need it. A combustion spudgun needs less than a millijoule to ignite. If you can see the spark (no matter how small the gap) it is sufficient to ignite a 1x mixture.

A 120 MFD phtocap charged to 300V contains ~5.4 joules. That's roughly 10,000 times more energy than is needed to ignite the fuel.

An average sized spud gun will launch a 100g spud with about 500 J of kinetic energy. So, the extra 5J from a high powered spark source has no affect on the performance of the gun.

If your setup will consitently spark across a 1/8" gap it'll ignite a 1x gun.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3127
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: Spudgun on Crack » Fri Apr 25, 2008 6:49 pm

I got it to work ok so now I am going to put the unit (Modded camera circuit, switches and battery) In a project box and then have the flyback mounted in a box say directly under the gun because its just to bulky to but in one big box.

If you don't know what camera mod I am using its on youtube.com

http://www.youtube.com/watch?v=8XXfEoDIF0Q

I made the video so please leave comments!!!!!!!

As soon as I finish it (1 to 3 hours) I will post a few pictures.
  • 0


Spudgun on Crack
Corporal
Corporal
 
Posts: 79
Joined: Sat Jun 23, 2007 4:43 pm
Reputation: 0

Unread postAuthor: TurboSuper » Fri Apr 25, 2008 10:16 pm

Cool video! Just one question: You say it charges very quickly...is this because it can handle more input voltage when it's isolated? How much did you use?
  • 0

"If at first you dont succeed, then skydiving is not for you" - Darwin Awards

TurboSuper
Brigadier General
Brigadier General
 
Posts: 986
Joined: Thu Jun 16, 2005 1:44 pm
Reputation: 0

Unread postAuthor: jimmy101 » Sat Apr 26, 2008 8:46 am

Spudgun on Crack: Nice job on the video. Never thought about hacking out just the high voltage oscillator from the photoflash board, that's an excellent idea.

Is it possible to omit the diode from your setup and use the one on the flash board or is the one on the board in an inconvenient place?

BTW, there is a small low ESR cap and another transformer on the board. You might be able to slice out that part of the board and use it as a wimpy spark source. Basically, the small cap does what the photocap does and the other transofmer does what a car ingition transformer or a flyback transformer does. You should be abe to get 5~10KV from the second transfomer, though at pretty low power levels (even for a HV spark).

TurboSuper: I wouldn't expect it to charge much quicker after this mod compared with the original board. If you put a volt meter across the cap a one or two second charge won't get the cap's voltage anywhere near the 300~330V that it'll get to after several seconds of charging. If SPOC had fully charged the cap the spark he got when he shorted the cap with the screwdriver would have been a fair bit bigger and louder.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3127
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Return to Combustion Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'