High Voltage Spark Unit?

Discussion in 'The Projects Forum' started by NM2008, Oct 26, 2008.

  1. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Hi,
    Does anybody know of a Spark unit/device that will produce rapid high voltage sparks across a spark plug, similiar to that of a car ignition.

    Ideally a self contained unit that once turned on will produce rapid sparking.

    Can such a device be purchased of the shelf?

    Thanks,
    Regards NM
     
  2. S_lannan

    Active Member

    Jun 20, 2007
    247
    2
    do you want to blow up something?
     
  3. triggernum5

    Active Member

    May 4, 2008
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    You can harvest everything you need to do that from an old tv/monitor.. That will give you 20-30kV @ a few mA.. Harvesting the parts can be lethal though if you aren't careful inside a tv/monitor even when its unplugged..
    Another option would be an ignition coil.. I'm not positive, but IIRC they can be hooked up to spark plugs..:)
    I'm not kidding about the danger though.. Research safe crt handling first.. HV and capacitors together are no joke..
     
  4. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    What!
    S_lannan think before you type!!!!
    NO, I do not want to blow up something.


    I have recently came upon a PULSE JET ENGINE, which needs a rapid spark, to start.

    But am wondering if there is an off the shelf "spark maker".
    I don't fancy building and testing a 20kv circuit.

    Regards NM
     
  5. bertus

    Administrator

    Apr 5, 2008
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  6. SgtWookie

    Expert

    Jul 17, 2007
    22,183
    1,728
    If I came across a pulse jet engine, I'd be firing that sucker up, too ;)

    Please ensure proper safety precautions:
    1) Clear any objects from within 10 feet of the engine prior to attempting start, or they will be sucked in, causing FOD (Foreign Object Damage). This includes removing jewelry, watches, and any items from your pockets.
    2) Ensure that engine is securely fastened to an item that cannot be moved by the engine; something large and very heavy.
    3) Clear away any flammable materials from within a 20 foot radius of the engine.
    4) Wear GOOD hearing protection. You can get soft foam earplugs at most drugstores, they work pretty well. Please do NOT attempt to start it without hearing protection, or you will suffer permanent loss of hearing. Jet engines are extremely loud; >125dB.

    Have a look at the attached; it's several variations on a similar theme using relays and an ignition coil to fire a sparkplug continuously. I haven't tested any of them, but they should work.

    Have a look at this fellow's page:
    http://www.asciimation.co.nz/beer/
    The world's first Jet Powered Beer Cooler! :D
    He used a 555 timer with a switching transistor to drive an automotive coil; briefly described on this page:
    http://asciimation.co.nz/turbine/page3.html#Contents
     
  7. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    SgtWookie.
    Thanks for the safety info, it always helps to keep it fresh in the mind, when attempting something new.
    Yes, from my research the pulse jet can an obnoxiously loud, and rather hot piece of equipment to be near.

    The one I came across will put out about 20lbs of trust, small I know, but plenty for first time, also well capable of producing ear drum bursting noise and flesh burning heat!!

    Also, thanks for the links and diagrams,
    The Beer cooler seems to be alot of hassle and fuel just to drop a few degrees, but interesting none the less.

    One question with regard to the diagrams you provided, could you tell me why is R1 the 10ohm 25W resistor needed?

    Thanks for your time.
    Regards NM
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    909
    I use an old-time, vibrating spark coil (AKA Ford Model T) for my pulse jet. Like this:

    [​IMG]

    1) Most or at least a lot of the air for combustion is said to come up the tailpipe. They do not suck things into their intakes like turbojets.
    2) Don't run it very long on the ground. They need to be moving for cooling.
    3) They are mostly a curiosity today.

    They do make a distinct sound and go through fuel like pouring it from a bottle. I wanted one since I was a very little boy; finally bought one in 1996. Haven't regretted it.

    John
     
  9. Sandman

    New Member

    Oct 26, 2008
    1
    0
    Have you looked into piezoelectric based ignition systems.
    They're inexpensive, self contained and can achieve voltages over 15K.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    Basically, the two circuits on the left side more or less replicate the points and condenser (capacitor) of pre-1975 automotive ignition systems. The old auto coils ran on 8 volts. There was a resistor in series from the +12.6v supply to the + terminal of the coil. During starting, the resistor was bypassed to make for a hotter spark; however the coil would overheat and points would burn up quickly if run continuously on 12.6v.

    If you will only need spark for a short period of time (say, 20 seconds) then you can omit the resistor. You'll be replacing the relay(s) much more often though.

    You can pick up such resistors for auto ignitions at various auto parts stores. Chrysler used a big sand-encased unit; that would work just fine.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    Very cool! I'm sure these can still be obtained; there are lots of Model T collectors, and lots of meets where they can be purchased. Might take some scrounging, though. The circuits I posted basically do the same thing, but with easier-to-obtain components.

    Interesting. I've never seen one run. I've seen LOTS of turbine engines running. The flight deck of an aircraft carrier is a very busy and noisy place. :eek:
    It would also seem that maximum thrust would not be generated unless it was moving pretty rapidly.
    Does yours have valves, or is it a valveless design? It's shape is very reminicent of the German V1 design.
     
  12. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Gosh, I had no idea those buzz boxes had become so hard to find. E-Bay only has one for sale currently at $5 and it looks pretty beat up. Apparently, they were in production until 1998.

    I did stumble on another link with a 555-based continuous spark ignition.

    That circuit actually uses a 556. One half produces the spark, and the other half is used to turn it on and off.

    My pulse jet is a newer design than the Dynajet. The Dynajet has problems with cracking at the welds. The newer design has seamless welds and is supposed to be much more resistant to cracks. It does have a flutter valve, but I don't remember off hand how many leaves it has. I use an ethanol/nitromethane mixture for fuel.

    John
     
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