Help with Engine Spark Sensor to Audio Output Circuit

[bigolow]

Hi All:

I would like to put together a high voltage automobile engine spark
sensor that would use an inductive connection to the spark plug
wire to drive a 555 Timer circuit that outputs a nominal audio
signal.

What I need is a circuit that would inductively interface the spark
plug wire to the 555 timer. If anyone has any ideas about this or
can give me a web site to investigate, please share. It would be
much appreciated. Thanks

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[John Woodgate]

I read in sci.electronics.design that bigolow <big@low.com> wrote (in
<42503498$0$28496$c3e8da3@news.astraweb.com&gt about 'Help with Engine
Spark Sensor to Audio Output Circuit', on Sun, 3 Apr 2005:

What I need is a circuit that would inductively interface the spark
plug wire to the 555 timer.

Why do you want an inductive sensor (which is relatively difficult) when
a capacitive sensor is so simple, - just a few turns of wire wrapped
round the HT cable?

You could experiment with a ferrite toroid slipped over the HT cable,
with say 50 turns of thin wire wound on it. Keep a low-value resistor
(10 ohms?) across this winding!
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[John - kd5yi]

"bigolow" <big@low.com> wrote in message
news:42503498$0$28496$c3e8da3@news.astraweb.com...

Hi All:

I would like to put together a high voltage automobile engine spark
sensor that would use an inductive connection to the spark plug
wire to drive a 555 Timer circuit that outputs a nominal audio
signal.

What I need is a circuit that would inductively interface the spark
plug wire to the 555 timer. If anyone has any ideas about this or
can give me a web site to investigate, please share. It would be
much appreciated. Thanks

----------------------------------------------
Posted with NewsLeecher v2.1 Beta 1
* Binary Usenet Leeching Made Easy
* http://www.newsleecher.com/?usenet
----------------------------------------------

Tune an AM portable radio between stations and bring it near the engine.
It's audible.

John

 

[Ken Smith]

In article <39yJHUKWsDUCFwmu@jmwa.demon.co.uk>,
John Woodgate <noone@yuk.yuk> wrote:

I read in sci.electronics.design that bigolow <big@low.com> wrote (in
42503498$0$28496$c3e8da3@news.astraweb.com&gt about 'Help with Engine
Spark Sensor to Audio Output Circuit', on Sun, 3 Apr 2005:
What I need is a circuit that would inductively interface the spark
plug wire to the 555 timer.

Why do you want an inductive sensor (which is relatively difficult) when
a capacitive sensor is so simple, - just a few turns of wire wrapped
round the HT cable?

He could be trying to see the fact that the actual spark jumped rather
than the fact that the coil made a high voltage.

This still could be easier to do with a capacitive coupling. When the
spark happens, a lot of high frequencies are made that are normally not
there.

You could experiment with a ferrite toroid slipped over the HT cable,
with say 50 turns of thin wire wound on it. Keep a low-value resistor
(10 ohms?) across this winding!

To extend this comment:

If you want to be fairly sure to get the inductive information, you really
should use a shield on the cable or over the core. Remember the shield
can't form a shorted turn though.

Here's what I'd try:

Copper foil can be obtained but just for messing about use some common al.
foil. Stick one edge of the al foil down along the cable. Cover the
first 1/2 turn of the foil with a layer of table and wrap about 1.25 turns
of foil onto the cable. Tape down the last edge. Connect the toroid to a
shielded twisted pair. Use the shield to ground the shield over the
cable. At the electronics: connect the conductors to a lowish resistor.
Connect the shield to ground.

Connect each of the conductors to the same location on the ground with.
lets say, 100 Ohm resistors. Using, lets say, 10K resistors run the
signal from the 2 conductors to a differential amplifier made from fairly
fast OP-amps.

--
--
kensmith@rahul.net forging knowledge

 

[Bob Eldred]

"bigolow" <big@low.com> wrote in message
news:42503498$0$28496$c3e8da3@news.astraweb.com...

Hi All:

I would like to put together a high voltage automobile engine spark
sensor that would use an inductive connection to the spark plug
wire to drive a 555 Timer circuit that outputs a nominal audio
signal.

What I need is a circuit that would inductively interface the spark
plug wire to the 555 timer. If anyone has any ideas about this or
can give me a web site to investigate, please share. It would be
much appreciated. Thanks

"a 555 Timer circuit that outputs a nominal audio signal." What? What kind
of an "audio" signal does a 555 put out unless it is running in an a-stable
mode? If it's a-stable how do you trigger it without a duration control
flip-flop of some kind or possibly two 555's? If it is the spark tick he
wants, why not pick it up capacitively as hs been mentioned and amplify in
an op-amp? I guess a better question would be what is this for and what is
the expected output?
Bob

 

[Mark Jones]

Pooh Bear wrote:

Bob Eldred wrote:


"bigolow" <big@low.com> wrote in message
news:42503498$0$28496$c3e8da3@news.astraweb.com...

Hi All:

I would like to put together a high voltage automobile engine spark
sensor that would use an inductive connection to the spark plug
wire to drive a 555 Timer circuit that outputs a nominal audio
signal.

What I need is a circuit that would inductively interface the spark
plug wire to the 555 timer. If anyone has any ideas about this or
can give me a web site to investigate, please share. It would be
much appreciated. Thanks


"a 555 Timer circuit that outputs a nominal audio signal." What? What kind
of an "audio" signal does a 555 put out unless it is running in an a-stable
mode? If it's a-stable how do you trigger it without a duration control
flip-flop of some kind or possibly two 555's? If it is the spark tick he
wants, why not pick it up capacitively as hs been mentioned and amplify in
an op-amp? I guess a better question would be what is this for and what is
the expected output?
Bob


I think he wants to make a noise box that goes brrrmmm brrrrmmm !

Graham

Indeed... no 555 needed for that. What about taking a FET with a 1-10M resistor
to gate, and couple this capacitively/inductively to the spark plug wire? Then
just buffer and amplify the output. Clicks at 6000 RPM (PPS) sound fairly
high-pitch...

For something useful, scale these clicks to 0-5V and buffer this into a PICs
comparator or external interrupt. Use a ripple-counted TMR0 to time the rising
or falling edges, then reciprocate that count to yield the frequency. JAL can do
24 and 32-bit floating-point math and my JAL FP2LCD display routine makes short
work of displaying FP values on a LCD. Try it, Mikey likes it!

DISCLAIMER: Don't bother if you don't know what a PIC is. Don't bother if you
fabbed PICs fourty years ago. Don't bother if you know it all. Don't bother if
you don't know Jack Schitt, or his wife Noe Schitt, or their sons Fulla Schitt,
Dip Schitt, Dumb Schitt, or their daughter Loda Schitt...

 

[Larry Brasfield]

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in
message news:39yJHUKWsDUCFwmu@jmwa.demon.co.uk...

I read in sci.electronics.design that bigolow <big@low.com> wrote (in <42503498$0$28496$c3e8da3@news.astraweb.com&gt about 'Help
with Engine Spark Sensor to Audio Output Circuit', on Sun, 3 Apr 2005:
What I need is a circuit that would inductively interface the spark plug wire to the 555 timer.

Why do you want an inductive sensor (which is relatively difficult) when a capacitive sensor is so simple, - just a few turns of
wire wrapped round the HT cable?

You could experiment with a ferrite toroid slipped over the HT cable, with say 50 turns of thin wire wound on it. Keep a low-value
resistor (10 ohms?) across this winding!

I'll just expand on John's answer, with which I agree.

Without considerable care in its construction, an inductive
pickup may well function as a capacitive pickup anyway.
For what the OP wants to do, those few turns together
with a very simple limiting network would be much easier.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.