How does the "Magic Electrol" system in Lionel Trains work? new problem!

The bell in the tender is turned on and off by a switch under the tender and has nothing to do with DC. Also in the tender is a slug relay. It operates on DC only, like a whistle relay. The reverse unit, e-unit, is in the engine. The power for the e-unit coil comes from the slug relay contacts in the tender. E-units operate when they are first energized. So when the slug relay gets DC, the contacts close and provide power to the e-unit coil, causing it to operate. Each time there is a new shot of DC to the slug relay it closes causing the e-unit to cycle. Unlike post war whistles, the reverse controller for magic Electrol just puts a rectifier in series with the power to the track.  There is no voltage boost and no AC bypass resistor.

I am more familiar with the 227, but I think the 201 is similar.  There should be three wires coming from the tender.  A wire on the right side is center rail power from the engine to the tender.  The wire on the left side goes from the accessory shoe on the tender truck to the front coupler on the engine. The third wire, which should be green, goes into the center jack.  It carriers power from the slug relay contacts to the e unit coil. 

If you want to just try out your engine without magic Electrol, connect the right hand jack to the center jack on the back of the loco.  This will connect center rail power to the e-unit coil making the engine run like a regular engine. Be careful not to continuously energize the left hand jack, as this will continuously energize the couplers and may burn them out. 

I'll give that a try.  Thanks.

Now you need to get the magic electrol controller. There's one on ebay with the box very rare. It's mine.

Eddie, I looked at some of the other items you are selling on eBay. You have a very fine collection. I am impressed.  

Ok, I received the 201 Loco and tender.  There are three jacks on the backhead of the loco, but only 2 wires leading from the tender.  also, although the seller stated that the loco ran in forward only, it won't budge.  i guess while being jostled in shipping, the e-unit might have set to neutral.   I don't have a magic electrol controller, so I am at a loss.  Any ideas?

From above:

“If you want to just try out your engine without Magic Electrol, connect the right hand jack to the center jack on the back of the loco.  This will connect center rail power to the e-unit coil making the engine run like a regular engine. Be careful not to continuously energize the left hand jack, as this will continuously energize the couplers and may burn them out.”

Is the tender marked? Is it a 201 tender?  Take the four screws out that hold on the shell on and see if there is a slug relay in it.  Or take the shell off the tender and post a picture of the inside of the tender.

basically still just a DC pulse to activate the coil. Was used to control reversing or uncoupling but not both in same engine. lead to the whole string of offering in the semi scale B-6 switcher, 227, 228, 230, 231, 232, 233. as well as in 201, 203 etc. I have documented wiring diagrams and succinct description of all of these in my "journal" on motors and such for prewar O

Your transformer whistle control will activate your Magic electrol relay.

Thanks for the replies.  I can't work on it now because I am getting ready to move to NC.  Will try your tips and get back to you all in a week or two.