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Improvising a spark plug indicator light ?

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Externet

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A friend is coming for me to diagnose spark loss in his ATV.
If I connect a disposable camera flash bulb (xenon) in series (or parallel?) to the spark plug, would I be able to see if there is high voltage pulsing for the plug to fire ? Would a series resistor be necessary ?
A neon may not be bright enough to see in daylight. Would it ? Suggestions ?
 

shortbus=

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Externet

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Thanks.
The one at Harbor freight is what I want to replicate, but real bright for daylight. Believe that has a neon gas discharge bulb in series to the high voltage lead and no additional power supply nor any circuitry. I have the bare xenon bulbs salvaged from disposable cameras, but prefer not to risk damaging them by blindly trying without some education.

The Walmart one sounds typical crappy chinese specifications. DC and high voltage ? On what kind of bulb ? Cannot believe such.
 

tcmtech

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Yes you can fire an ignition coil pulse directly through a xenon or mini neon bulb in series with a spark plug without damage.

The xenon flash tube might take several hundred volts to break over though whereas the mini neons only take several tens of volts but in a good working ignition system that's not really an issue.
 

shortbus=

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Yes you can fire an ignition coil pulse directly through a xenon or mini neon bulb in series with a spark plug without damage.

The xenon flash tube might take several hundred volts to break over though whereas the mini neons only take several tens of volts but in a good working ignition system that's not really an issue.
You sure about that? Any xenon timing light I've ever seen uses two extra wires to the battery for the internal circuitry, to power the bulb. And then a split pickup coil that goes around the spark plug wire for the trigger.

And the disposable cameras use two circuits one to power the bulb and another to charge a cap at ~400VDC that is then sent through a transformer to make a much higher trigger voltage pulse.
 

rfranzk

Member
Hello All,
What about using and inductive clamp timing light? This would be non intrusive, the atv should have 12v source. If you wanted to hold the trigger with a nylon tie wrap or electrical tape the business end of the light could be placed in a visible spot while using the atv.

rfranzk.
 

debe

Active Member
Yes you can use a small disposable flash camera Xenon tube betwean the plug & the lead. Its not as bright as when used in a camera application, but its certainly usable as an indicator of ignition pulse. And beter to see than the Neon type. Was rather difficult to photograph.XENON TUBE.1.JPG XENON TUBE.2.JPG
 

tcmtech

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You sure about that? Any xenon timing light I've ever seen uses two extra wires to the battery for the internal circuitry, to power the bulb. And then a split pickup coil that goes around the spark plug wire for the trigger.
Yes, I am sure about that! :p

The Xenon flash bulb won't be very bright on the few tens of ma that an ignition coil and spark plug run on but it will flash a dull white streamer as Bebe's pictures show. Mini neons however tend to light up bright orange with that current level. ;)
 

spec

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Would this work: 20mA high brightness LEDs in series with the plug?

spec
2016_06_15_ETO_EHT_TESTER.png

 
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bountyhunter

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Hello All,
What about using and inductive clamp timing light? This would be non intrusive, the atv should have 12v source. If you wanted to hold the trigger with a nylon tie wrap or electrical tape the business end of the light could be placed in a visible spot while using the atv.

rfranzk.
+1 Best way to check for spark.
 

rfranzk

Member
In the past I have monitored the primary side of the coil with a simple led and current limiting resistor across the coil. Most ignition modules switch the negative side of the coil to collapse the field and induce spark. If you monitor just the secondary it could indicate no spark but not sure if it is coil or module related. If you lose a primary signal it indicates module or pickup coil on the primary side. You could add a length of wire to the handle bars and monitor the led while using the atv. I assume this is an intermittent problem which can be tricky to troubleshoot.

Thanks.
rfranzk.
 

spec

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To more comprehensively fault-find you need a monitoring system that can display both the secondary voltage amplitude and the waveform. This is especially the case with modern engines. In particular, the UK BMW petrol engines, which have a coil for each plug, can develop some weird problems while still operating a rudimentary light type indicator OK.

Although I have not tried this out, one possible way to monitor the secondary waveform is with a 100M Ohm low inductance resistor for every 20KV that you wish to monitor. Most modern ignition systems operate in the range 15KV to 40KV but the older systems and lawn mower Briggs and Straten types are more like 15KV. A lower value resistor, say 5K, would then be added in series at the earthy end which could be monitored with an oscilloscope. It would be wise to put a bidirectional TVS across the low value resistor. Suitable 100M, 20KV and above resistors are available from Craddock and Ohmite for example.

The peak current in the secondary is typically 10mA, as far as I can tell, but with some high performance coils the peak current can be higher. http://www.auroraelectronics.com/ignition_systems_-_basics_to_high performance.htm

spec
 
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shortbus=

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Yes, I am sure about that! :p

The Xenon flash bulb won't be very bright on the few tens of ma that an ignition coil and spark plug run on but it will flash a dull white streamer as Bebe's pictures show. Mini neons however tend to light up bright orange with that current level. ;)
Like I said in first reply,"I may be wrong". Didn't know they would flash at all without the primary power on them. Learn something new all the time.
 

dr pepper

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While a xenon tube may work on a good condition well performing system, on one suspected faulty I dont think thats a good idea.
I fault find on gas(lpg) industrial engines, for a quick check I use a 'volt stick', it works well as a go/no go test and doesnt need any intrusion to the system, just hold it near a ht line.
 

Externet

Active Member
Many, many years ago, I wrapped each high voltage wire with a couple of inches of aluminium foil on my 4 cylinder engine.
Attached a two-pair telephone wire, one wire to each foil and brought inside trough the firewall to 4 neon bulbs in a tiny 'cabinet ' display.

Worked great in low light. Now I was after a brighter single 'telltale'
I believe I should try a xenon bulb in parallel to the spark plug to find how behaves that way, if impairs the spark or not.
 

tcmtech

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For inline ignition testers the way I always made them was to put a mini neon bulb in series with a spark plug wire and have the bulb encased in a clear plastic tubing filled with clear silicone to keep the wires secure and the bulb safe to handle when active. Put a spark plug wire cap on one end and put an old ceramic spark plug body on the other lead and you're good to go!
 
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