magnets in a pertronix

[minger]

I finally got around to swapping the pertronix pointless system from my old dizzy to my new one. When I pulled the plastic disk from the rotor, the plastic seperated and I had 4 little magnets and two pieces of plastic. I reassembled the magnets into the disk (wow are those magnets strong. They kept leaping out of their slots and onto each other) and clipped the plastic together and ta-da, installed it onto the new spindle.

Then I got to thinking: does it matter which way the magnets point. I realize that a flipped magnet will create an opposite flux through the sensor but does that matter?

Why was I thinking that? The reason I was swapping in the system was my points were shot an making a weak spark. Now I have a better spark but only on 2 cyclinders. It was late last night when I did this and haven't had time to trouble shoot but I was thinking about the reversed magnet field en route to work today. Thanks to y'all and to Faraday's Law.

[anthracitedub]

Mine fell apart the same way also.... Been Rollin points ever since.

[yamaducci]

Yes it matters. Otherwise there would be no need for a magnet at all. Good thinking. They should be set up to "Attract" the pick-up module.
Once you get them sorted and tested a couple drops of crazy glue to hold the plastic disk together wouldn't be a bad idea.
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[Dale M.]

Actually it would be a Compufire unit and not a Pertronics and no it does not matter polarity of magnets.... All sensor wants to see is magnetic field build and then collapse when magnet passes over sensor (hall effect transistor most likely) .....

Electronics module is basically a on/off switch just like points, it either functions or it does not....

Dale
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Lives his life vicariously through his own self...
1970 "Kellison Sand Piper Roadster" For Street & Show.

All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[yamaducci]

[minger]

I get the Hall effect tranducer and how it works but that means a reversed magnet will give the same potential but with reversed sign. So if there is a diode some where, then reversed signal would be blocked.

I am leaning towards the polaryt doesn't matter. Gonna pick up a set of new points and install those and then work from there. That or I could drag the the 1970s oscilloscope home from work but don't feel like doing that. Though that would maybe impress the neighbors.

And I am pretty sure it is petronix. Doesn't compufire have the frisbee thing? i don't have the frisbee. I have this set up:
http://www.pertronix.com/prod/ig/ignitor2/default.aspx

I've emailed pertonix tech help. I will report back.

[Dale M.]

Yes Compufire has the frisbee thing.....

Didn't realize Pertornics has magnets imbedded the ring.... Though ring was just polarized magnetic material.... I run Compufires in both my motors....

Dale
_________________
Lives his life vicariously through his own self...
1970 "Kellison Sand Piper Roadster" For Street & Show.

All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[Dale M.]

[minger]

Transistors have a bias; they can very much work or not work depending on the direction of the current. That is how they function as a switch. Reversing a magnet would reverse the current direction and it would then try to flow 'upstream' relative to the transistor. Faraday's Law is a vector equation.

Pertronix wrote back. Turns out polarity matters so that all the magnetic fields must point in the same direction.
Haven’t had the time to try to fix it yet.

[anthracitedub]

Have you inquired with pertronix to see if the magnet can be purchased seperatly? Just wondering, I wouldn't mind having one to replace mine with.

[74 Thing]

You can buy just the Pertronix magnetic wheel here...
http://vwparts.aircooled.net/Magnetic-Trigger-Whee...-wheel.htm

[anthracitedub]

Ahh, thanks man! Funny thing is.... My brother mailed me one in a package... He had it wrapped in a paper towel. I didn't know, so it got thrown away

[Dougy Dee]

Polarity matters. That's why only two cyl's are working. If polarity didn't matter the magnets could be installed with no regard for polarity and the unit would work.

A few years back I had 1 bad cyl after scattering the magnets, OOPS. Put them back in and chased one bad cyl for a week or so. Finally remembered the OOPS and checked for attraction/repelling with another magnet. 3 stuck and one repelled... Flipped the errant magnet over and everything worked again. So... yes. Polarity mattered.

[Bcoe]