2engsout
Posts: 100
Joined: 2/8/2003
From: omaha, NE,
Status: offline
|
Hi Bill, I looked at a 26, 2 weeks ago and did not actually test the magnets on the twin sync hall sensor, but, I would assume that both magnets would have to be North to talk to the ignition sensor. I would also assume that as the propdriver rotates past the ignition sensor, it ignores the first magnet when you flip it over and reads the 2nd magnet polorization to create the spark, at which the piston is now within 2 degrees before top dead center, which makes for an easy starting engine. I would next assume that at aprox 2500 rpms, the ignition module THEN starts to read the 1st magnet polorization it sees, and electroniclly advances the timing to full advance. That timing curve is programmed into the module , but not published. Most 2 stroke engines have 28-32 degrees at full advance. Even though the 1st magnet passes the sensor approx 90 degrees before top dead center, the module compensates for this. If you dont want to use a spinner on the prop, and dont want a backplate of any type behind the prop to hold the magnets, the only concievable way I know to get the twin sync to work on the 26 is to use a diametric magnet mounted in the prop hub opposite the ignition magnets, with the South pole outboard from crank centerline, so it will NOW polorize the OTHER SIDE (side opposite from the side with the writing on it) of the twin sync hall sensor, and NOT effect the ignition hall sensor. THEN, you could mount the twin sync hall sensor on the opposite side of the engine case from the ignition hall sensor. This ONLY works IF, the twin sync polorization magnets are opposite poles from the ignition magnet poles, AND there is NO RF leakage emmiting from the ignition hall sensor lead to send false signals to the twin sync hall sensor, AND, the spark plug high tension lead is suffiently shielded for RF. This theory would have to be tested to be conclusive either way. If there is leakage, then you could shield BOTH hall sensor leads. The ignition lead, all the way to the module, and the twin sync lead, at least 12" past the module on its jouney back to the twin sync unit. My recommendation, if you dont use a spinner on your prop, then use a 3/32" thick aluminum backplate behind the prop approx 1.5" bigger in dia. than the propdriver to mount the twin sync magnet. Then use a hardwood 3/8" x 3/8" standoff bolted to the engine mount rail to hold the hall sensor in place with a 1/16" air gap. Rick Simmons
|
Printable Version
All Forums >> RC Airplanes >> Twin & Multi Engine RC Aircraft >> RE: Eletronic engine syncronizer **SUPPORT ** 
RE: Eletronic engine syncronizer **SUPPOR... - 
