LED in-line spark tester
 

Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp

LED in-line spark tester
 

"edolo" wrote in message
...
Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp

Would be probably as cheap and even more handy to just get an inductive
pickup timing light.

LED in-line spark tester
 

know any LED's which can handle 12,000volts?
"edolo" wrote in message
...
Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp

LED in-line spark tester
 

"Short Wave Sportfishing" wrote in message
...
On Tue, 19 Dec 2006 16:09:04 -0500, "news.wildblue.net"
wrote:

know any LED's which can handle 12,000volts?

?

About 2,000 or so of them in series.

LED in-line spark tester
 

"news.wildblue.net" wrote in message
...
know any LED's which can handle 12,000volts?
"edolo" wrote in message
...
Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp



All with a little added circuitry.

LED in-line spark tester
 

news.wildblue.net wrote:
know any LED's which can handle 12,000volts?


Why would it have to handle 12,000 volts?

LED in-line spark tester
 

Your better off buying a tester off of ebay for 30bucks that
can test the plug and voltage (strength) of the spark.
Just clamps to the batter and one plug at a time.

If you just want to see it fire, the little light testers that go on
there for $5.00 will due ok. (small light encased in clear plastic
that goes in between the spark plug and the plug wire.

Building one out of leds??? Most likely more work that its
actually worth.

Tom

edolo wrote:
Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp

LED in-line spark tester
 

that's about the firing voltage of a spark plug.

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

news.wildblue.net wrote:
know any LED's which can handle 12,000volts?


Why would it have to handle 12,000 volts?

LED in-line spark tester
 

Thanks all! Yes you can build a circuit to take even 50,000 volts,
but that's beside the point. Sure I could spend four hundred a buy
the real thing, but where is the fun in that - & besides, I was
thinking of taking the four hundred with me when I go. cheers!!!

On Wed, 20 Dec 2006 16:23:03 -0500, Gene Kearns
wrote:

On Tue, 19 Dec 2006 18:32:06 GMT, edolo penned the following well
considered thoughts to the readers of rec.boats:

Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp

I remember seeing these things 40 years ago. IIRC.... think neon....
Anyway, the parts might be difficult to obtain. See Mouser and the
like.....

LED in-line spark tester
 

You want one of those little neon panel lights. Add a fairly high
value resistor and you have a spark detector.

edolo wrote:
Thanks all! Yes you can build a circuit to take even 50,000 volts,
but that's beside the point. Sure I could spend four hundred a buy
the real thing, but where is the fun in that - & besides, I was
thinking of taking the four hundred with me when I go. cheers!!!

On Wed, 20 Dec 2006 16:23:03 -0500, Gene Kearns
wrote:

On Tue, 19 Dec 2006 18:32:06 GMT, edolo penned the following well
considered thoughts to the readers of rec.boats:

Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp

I remember seeing these things 40 years ago. IIRC.... think neon....
Anyway, the parts might be difficult to obtain. See Mouser and the
like.....

LED in-line spark tester
 

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.....

LED in-line spark tester
 

You can't add resistance to the circuit and make an led light up from a
spark. The led needs a certain amount of current at around 1 volt.
There is not that much current in the spark. The coil trades currrent
for voltage when it steps the voltage up to that many volts. You would
need to build a trigger circuit tha detects the spark and the powers
the led.

basskisser wrote:
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.....

LED in-line spark tester
 

"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?

LED in-line spark tester
 

Why in the world go to all this trouble when neon bulb spark detectors
are under a buck apiece?

Terry K

LED in-line spark tester
 

"D.Duck" wrote in message
...

"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.

LED in-line spark tester
 

"RCE" wrote in message
...

"D.Duck" wrote in message
...

"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.

LED in-line spark tester
 

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
...

"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.

LED in-line spark tester
 

"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
...

"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.

LED in-line spark tester
 

"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
...

"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.




There is enough current to light a LED. the ignition, even point and coil
take a fairly good flow of current to run. And a LED requires less than 10
milliamps to light.

LED in-line spark tester
 

edolo wrote:
Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp


Wouldn't a neon glow lamp be a better choice than an LED?

LED in-line spark tester
 

James, sounds like a good idea ... & sample of glow in:
http://www.giangrandi.ch/electronics/neon/lamps.html
What resistance would you suggest?
Might be easy to enclose in a ballpoint pen case.
alp

On Sat, 23 Dec 2006 07:32:03 GMT, James Sweet
wrote:

edolo wrote:
Have a couple of manual testers, but would like to build an LED
in-line unit to test spark on two, four, and six cylinder outboard
motors. Anyone have a design or know where such a unit can be obtain?
tks, alp


Wouldn't a neon glow lamp be a better choice than an LED?

LED in-line spark tester
 

edolo wrote:
James, sounds like a good idea ... & sample of glow in:
http://www.giangrandi.ch/electronics/neon/lamps.html
What resistance would you suggest?
Might be easy to enclose in a ballpoint pen case.
alp



You shouldn't need a resistor, in fact you might not even need to
connect it directly, holding it near the plug wire it may pick up enough
energy to glow.

LED in-line spark tester
 

James Sweet wrote:
edolo wrote:

James, sounds like a good idea ... & sample of glow in:
http://www.giangrandi.ch/electronics/neon/lamps.html
What resistance would you suggest?
Might be easy to enclose in a ballpoint pen case.
alp



You shouldn't need a resistor, in fact you might not even need to
connect it directly, holding it near the plug wire it may pick up enough
energy to glow.

It is possible to get a faint indication from capacitive pickup with 20
or 30 turns of hookup wire round the outside of the plug lead to one
side of the bulb with the other well grounded to the block, but any
attempt at resistive pickup with a direct connection to the spark plug
wire will almost certainly shunt your spark and shut the engine down.
High voltage resistors that can standoff that sort of pulse voltage dont
come cheap new and are difficult to scavenge and any lesser resistor
*will* arc over.

I'd look at putting a fairly substantial neon bulb WITH NO RESISTOR in
series with the HT lead. The drop accross it will be low enough so the
spark is not noticably affected, the only question is can the neon
handle the peak current?

I dont think the ballpoint pen housing idea is going anywhere, too
narrow diameter. I've made low voltage probes from BIC pens before,
knocking out the actual ball from the brass tip and soldering in a brass
plated pin for a probe point, but the most I've ever fitted inside is a
small LED and resistor. No way I'd trust the casing for insulation at
tens of KV either. I cant think of any common household item to
canniblise for a casing so I guess I'd be using two pieces of clear
vinyl tubing one inside the other, or maybe vinyl tube over a glass tube.

For a radical idea, do the neon voltage test screwdrivers still have
seperate resistor and neon bulb capsules inside them? If so, remove the
resistor and the pocket clip and discard. Solder the connecter off the
end of an old spark plug lead into the hole in the brass top plug and
stretch the spring enough to make up for the missing resistor. Cut the
blade end down to a short stub and cut back the insulation. turn and
thread to match the top of a spark plug

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.