P-Lead Output

[jlisler]

What kind of signal is on the P-Lead of a Slick magneto? Is it a voltage, a pulse (as in the points opening and closing) or what? What is the magnatude of this signal?

Thanks,
Jerry Isler
Donalsonville, GA
RV-4 N455J
10.6 hours and counting

[mahlon_r]

The points, in a mag, just open and close the primary coil circuit in the mag. There is no voltage supplied to the p lead system from the aircraft. The p lead itself just grounds or un grounds the plead circuit in the mag.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

[DanH]

With the P-lead ground open (mag ON, engine running), an o-scope attached to the P-lead should show a significant variation in voltage with opening and closing of the points. Voltage will be low with the points closed and the rotor magnet sweeping the primary coil. When the points open the coil's magnetic field will collapse and induce as much as 300 volts in the primary winding.

Voltage (and amperage) with points closed is a function of magnetic flux strength and the speed at which it sweeps the primary coil windings. Flux is fixed but speed varies with RPM. Voltage peak when the points open is a function of amperage created during that sweep, capacitance, and the condition of the points.

[MCA]

Jerry,

We did some testing on the p-leads as part of our product develoment. Here's a link to a thread that hopefully sheds more light on your question.

http://www.verticalpower.com/forums/showthread.php?t=37

Marc