Magic Electrol

[lionelsoni]

I'm afraid that Peter Riddle's attempt to explain magic electrol in the February, 2011, CTT suggests that he doesn't quite understand it.

Magic electrol was Lionel's prewar scheme to control separately the e-units of two locomotives running on the same track.  One locomotive was unmodified, so that its e-unit responded to track-voltage interruptions in the normal manner.  The other locomotive was rewired to use a whistle relay to step the e-unit rather than operate a whistle.

Where Riddle starts to go wrong is where he writes about the whistle relay, "The only change was in the switch itself.  Whereas in the whistle application, activating the relay turned the switch on, in the Magic Electrol tender the relay turned the switch off."  As a look at his figure 8 shows, this is not the case:  The relay has the same normally open type of contact (form A) as a normal whistle relay, not a normally closed contact (form B).

He goes on to say that interrupting the track voltage with the direction button "has no effect on the [magic-electrol-equipped] engine, other than to dim its lights momentarily."  In fact, if the e-unit were normally energized as he says, removing the track voltage would cause it to step, there being no power source on-board to keep it energized; and both locomotives would be affected, not just the unmodified one.

But, with the wiring as Lionel actually did it, using a normally-open relay contact, the modified locomotive's e-unit would normally be unenergized and therefore unaffected by the track-voltage interruption.  On the other hand, the DC voltage from the whistle controller would energize the modified locomotive's e-unit and step it, without affecting the unmodified locomotive.  This is of course how it was meant to work.

It would also be better if the article did not overuse the term "solenoid", which applies to a hollow coil with a plunger moving inside of it.  The only solenoid on the locomotive is in the e-unit.  The relay's winding is called simply a "relay coil".

I would think that readers interested in the electrical details of magic electrol would also like to know just why the whistle relay operates only on DC, rather than having it dismissed as "simply an on/off switch that responds only to direct current."  The cause of this relay's peculiar behavior is easily seen in figures 7 and 8.  It is the two copper washers surrounding the lower end of the pole piece.  The AC current in the relay coil induces a current in the washers opposite in phase to the coil current, causing the washers to cancel out the alternating magnetic field at the end of the pole.  The lack of a magnetic field there means that the armature is not attracted to the pole, as it otherwise would be.  But this induction effect occurs only with AC fields.  When there is DC current in the coil, the washers do not shield the steady component of the magnetic field at all; and the pole attracts the armature and closes the contact.

[phillyreading]

While I don't know a whole lot about the magic electrol, I found an article in an older Lionel instruction manual from the late 1940's. It mentions how to control the two trains on the track. Not 100% sure but I think that magic electrol was a premium O gauge set.

Lee F.

[arkady]

I had never heard of the term "magic electrol" until now.  I found an online article that explains it for others who've never heard of it, either:

http://www.toytrainrevue.com/relay.htm