The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Buster1450 on 13.01. 2011 10:04
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Hi Chaps
Could someone tell me if the regulator box on an A10 be isolated from the earthed frame of the bike?
Cheers,
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Hi Buster... No, it is not isolated at all and I can see why you ask that. The rubber bushes on either side of the regulator are there to act as a cushioning effect and not as an isolator.
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There was a topic during the last week where the advice was that the frame of the regulator is not earthed to the frame and is at a floating potential - maybe the rubber mounts serve the purpose of insulating the reg frame from the bike frame and also insulate from vibration.
Jim
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I can't see any advantage to isolating it. I would have thought the earthed metal screening would help prevent the bike from causing interference on radios and tellies.
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There was a topic during the last week where the advice was that the frame of the regulator is not earthed to the frame and is at a floating potential - maybe the rubber mounts serve the purpose of insulating the reg frame from the bike frame and also insulate from vibration.
Jim
Thats the reason i asked the question as not sure myself.
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The rubber mounts were only introduced with the RB107 regulator.
The early MCR1 & MCR2 were bolted to the frame with no rubber cushion.
The "frame" or "chassis" of the regulator is directly connected to the "D" output of the generator.
Trev.
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I'm reading the question differently; the floating regulator frame is connected to the 'D' terminal on the dynamo. The regulator frame is not connected to the bike chassis. It should be electrically insulted in the regulator.
Stu
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The reg can be solidly mounted if you want it that way which tells you it doesn't matter if the body touches or not. There is a separate earth wire marked "E" anyway .
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Not going into the isolation question, don't need my 2p on that point.However, regarding screening, don't get confused. There is not enough current cursing through the regulator (as is present in the plug wires when the magneto dumps its load once a revolution) to cause the kind of electromagnetic field necessary for electromagnetic interference in radios. Even if there were, the aluminum regulator cap affords no shielding to electromagnetic waves, being non-ferrous. Now then, I believe the spark itself is another issue. I think it is a source of mostly electrostatic energy, which can be shielded by aluminum.
I know. "So, what?" and "Who cares?"
Richard L.
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A car dynamo could certainly cause interference on that car's radio.