Spark Plug - Interference Suppression Resistor

Decent explanation here:

http://www.vishay.com/docs/30255/an0004.pdf

kramarat:
Very nice. Thanks for quick and good link. I never knew that they use such thing to avoid accidental explosion. Perhaps, it may be an idea to avoid explosions due to tribo-electricity.

Good document, thanks.

I never realised before that they had also an inductive component.

Andy Germany: Nice to see you.

You got it right. These simple looking devices are in fact high technology tools. To suppress the RF noise and also to minimize DC currents these in-line resistors inside the spark plugs are specially designed. Typical Ohmic values are between 1k Ohms to 15k Ohms and the self-inductance between 10 μH to 1 mH as per reference from Vishay catalog.

You might find something here....

http://www.bigshoppage.com/high-voltage-plug

CR4 Admin: disabled broken link 12/28/2018

to suppress noise in the electrical system

Fredski

No. These are very specific to spark plug, detonators etc. I do not know where else they may be used but I may also use for current control in high voltage applications for frequencies up to 10MHz as they are linear due to low inductance value and low capacitance value. I have asked for their power rating from Vishay as these 1K to 15K resistors are rated for 50kV but I am not sure of their average power rating.

I am following the link given to me by kramarat.

best to go with Kram, he's far smarter than I am

Yeah, that's me alright. I beat Lyn to the google draw.

I undid your OT, since that's exactly what I was thinking was the answer.

I thought about buying some of those plugs one time, but they were about $50 apiece...or something expensive. I skipped it.

I never bother hitting the OT its all good

I don't use the OT button either, unless it's on myself. Otherwise, the single OT votes are just annoying.

Glad that link helped Shyam.

kramarat:

These are not that expensive here. However there are many designs and I want to make sure of every specifications of those are manufactured in India by Bosch (MICO BOSCH, Bangalore, India). I think they are only $2 to $5 range here. My assistant had few spare ones so I am planning to test them.

I was interested in making some sensors out of these also and they have excellent insulation of ceramic and two electrodes. They can be directly used as capacitance type sensors. That is why I am looking for some fitted with BNC / SHV / SMA connectors. I think Kistler were manufacturing with pressure sensor inside the spark plug. These can sense the pressure generated during fuel firing. Some of these also come with temperature sensors.

These parts are so cheap and ready made available in every corner of the country, I am tempted to use them in many applications.

Good deal.

They were a fairly new product when I looked at them. Let us know what you come up with.

kramarat:

In my personal mail this appeared.

kramarat:

Spark plug with center electrode are just for HV arc pulse firing purpose or ignition trigger which may require only <10mA current.

Those fitted with piezoelectric pressure sensor at center have firing electrode inserted in between body and sensor crystal.

As I have expertise in charge amplifiers, anyone interested in testing bike or car engine or rocket science, Mars mission, I may be able to extend help. If you end up with any question there - you may very well ask me.

I may also procure few sensor spark plugs from Kistler.

Thanks for the info.

I don't personally have any need for them at the moment.

I may never recover

Don't ya hate it when you try to help somebody out and they crap right on ya....The good professor seems to be a bit stuffy, and I would imagine his arse kissing is quite fickle as well.....

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I don't think I can add anything.

It should be a simple matter to add the correct connectors to both ends of the co-ax.

Shielded spark plug wire is common but I don't know if the impedance is correct for this application.

lyn:

Impedance for which application?

For firing fuel one does not require high current. All one requires is few million electrons and acceleration voltage which is often high enough above 15kV and can be up to 45kV. Remember those gas lighters used for firing LPG based on Piezo Electric Crystals easily ignite LPG. Piezo electric crystals often have large impedance and that is how they can hold the charge.

If we use a transducer of either Piezo Electric Type or Piezo Resistive Type, we need to shield that part separately and a coaxial cable is mounted in the center. In that case a firing electrode is inserted carefully in between the body shield and the transducer.

I thought of using a small duct in the center to transfer pressure for sensing but then drag from walls will affect the pressure wave-front badly. Best way is to have the pressure sensing crystal right at the end of the spark plug. Another problem could be the temperature of the combustion fuel which may destroy the sensor beyond a Curie Temperature.

I have used some Kistler transducer for under water explosion in pipes in which perhaps RDX was the explosive used by the helping defense team. We were scientific team so our aim was to trigger the explosive and synchronously record the pressure pulse and then look at mechanical deformity in the pipes. Here our experiment is with liquid fuel vapors mixed in air detonated by high voltage electric arc spark.

Does any one know the time required for spark to take action? I think this may be of the order of milliseconds, but can we trigger in few microseconds or even in nanoseconds spark?

These may help:

INTERNAL combustion engines.pdf - University of Notre Dame

Chapter 7.

Spark ignition: its physics and effect on the internal combustion engine

Abstract shows a time graph.

lyn:

These are basic thermodynamics we all study in undergraduate classes right from Carnot heat engine. There has been lot changes thereafter to gain high acceleration in race car, aircraft and space vehicle rocket engines.

I am considering the Hydrogen fueled internal combustion engine. Somehow I want to get rid of Hydrocarbons. Perhaps I will like to have a Hydrogen Generator and all related stuff and I want to watch out for the dangers of explosions from Hydrogen leaks as well.

Do you have some idea on which material is the best for highest volume expansion pressure generation that can be used for Rocket propulsion and Cannon firing? I want to shoot small payload of about 1kg (consisting of sensors, battery and data recorder) in the lower atmosphere up to 1km to 10km for atmospheric data monitoring.