"James" wrote in message
nk.net...
In the case of the neon lights the bulb and resistor is in parallel with
the spark plug.

There is not enough current to light an led in an ignition spark.

"Calif Bill" wrote in message
nk.net...

"RCE" wrote in message
...

"D.Duck" wrote in message
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"basskisser" wrote in message
ups.com...

news.wildblue.net wrote:
that's about the firing voltage of a spark plug.

Yes, it is, but that doesn't mean the LED has to handle that 50,000
volts. Think resistance.....

How much resistance would you need? Series, parallel?


Last time I checked (which may be very outdated info) an LED's forward
bias "on" was around 3.6 volts DC or something like that. You'd need a
voltage divider network to supply that to each LED or enough LED's in
series that the voltage drop across each was in that ballpark.

The series resistor is to limit current ... it depends on the rating of
the LED. It's been a long time since I played with them, so take it for
what it's worth .... which is nothing.




Enough resistance to allow the LED to light and be usable again, would
stop the spark at the plug.



A simpler method might be to wind a few coils of wire around each plug wire
and connect them to the base of a triac and ground. Use a conventional 12
volt LED circuit, running off the car battery with an LED and triac for each
plug wire (cylinder). When the plug fires, the coil will briefly turn on
the triac and associated LED.