Connecting the P-Mag tach signal to a JPI 740/800 series

[RV7ator]

How do you wire a P-mag to a JPI 740 instrument? The 740 wiring diagram wants "RPM +5v" and "RPM ground" besides the tach signal; the P-mag has just a tach signal output. I suppose the answer revolves around what to do about the voltage. But there's always the matter of pulse frequency matching and perhaps more than simply joining the signal wires.

John Siebold
Boise, ID

[Radomir]

JPI uses the hall effect sensor that is installed into that vent hole in regular magnetos.. If P-Mag can "simulate" the output of that sensor, then that'd work..

This is what works with JPI:

http://www.aircraftspruce.com/catalo...clickkey=10133

So you need to ensure that PMag outputs match what this sensor does..

[RV7ator]

JPI can use Lightspeed's tach signal and ground. I'm hoping that's true for P-mag. Thanks, but MGL's contraption doesn't match up.

John Siebold

[Radomir]

This is not an MGL product, contrary to what it says on Spruce site.. it's an UMA hall sensor. I have one w/ my JPI... first hand experience..