Electrical Q regarding Lionel Docksider

[FJ and G]

Reverse is accomplished by reversing polarity to the motor.

Yep, no need for a "reverse unit".  This is also why some of the lower end motorized units only run in one direction.  No "e" unit and a simple bridge rectifier that takes the AC and feeds DC to the can motor.  If you feed it DC, it will still work.  It will also still only run in one direction irregardless of the polarity of the input DC.  Take the bridge out and now you can go in either direction with DC by switching the leads.

 http://www.answers.com/topic/diode-bridge

I have a lower end motorized unit that runs in just one direction. I rigged up a DPDT switch so it can go in forward, reverse and neutral, but that's accomplished manually.

Here's that particular loco, a Lionel yellow construction loco I repainted. Above the "S" in santa fe on the roof, you can see the silver color dpdt switch.

[chuck]

Reverse is accomplished by reversing polarity to the motor.

Yep, no need for a "reverse unit".  This is also why some of the lower end motorized units only run in one direction.  No "e" unit and a simple bridge rectifier that takes the AC and feeds DC to the can motor.  If you feed it DC, it will still work.  It will also still only run in one direction irregardless of the polarity of the input DC.  Take the bridge out and now you can go in either direction with DC by switching the leads.

 http://www.answers.com/topic/diode-bridge

[rogruth]

Don't the two rail DC guys use dpdt switches like with non dcc HO? There are no reverse units in the HO stuff. Reverse is accomplished by reversing polarity to the motor.

[poppyl]

Good question, Bob.  The two rail boys seem to be able to do it.

Poppyl

[lionelsoni]

That's not very enlightening.  I had imagined that it just might be possible to run a DC motor on DC.  The question is, why won't the reversing unit run on DC?

[FJ and G]

Thanks, guys for the info. Here's what Lionel techy sent me just now:

"The reversing unit in the locomotive is designed to receive a/c power.
If you disconnected it and ran power directly from the track to the
motor, you could use d/c as it is a d/c motor.

Thanks,
Lionel Tech."

[chuck]

There are some pretty big differences between converting the loco from AC to DC and converting from three rail to two, e.g. pickups, frame isolation, etc.. 

If you just want to run the thing on DC current on three rails:

If the loco is packed with modern electronics, yank em.  The circuits were designed to run off of AC and may need the ac frequency for some of their functions. 

Forget any sound boards (same reasons)  and you may need to rework any lighting harness.

One thing of note from the previously cited web was that the issues with the dock sider in reverse may have more to do with the smoke unit's mechanism than the actual drive train.

The old open frame motors were "universal" and could work on AC or DC.  While modern equipment has DC can motors for the actual drive mechanism, ALL of the rest of the electronics were designed for AC for purposes of backwards compatibility.  They could (and probably should have) designed all of the boards to work on AC or DC but this would have made the stuff more expensive so they didn't.  If we leapfrog the last 20 years of design you can now make boards that will work well in either environment at reasonable prices AND reasonable size.  This is now, that was then.

[Anonymous]

Try this guy for info.  He has two railed Docksiders  http://mywebpages.comcast.net/omodeller/.

 

Smokebox

 

[FJ and G]

thanks; will send off inquiry

[brianel027]

It's got to be something specific to that locomotive Dave. Might not even hurt to ask Lionel direct. Most locos with no sound but DC can motors specify that those locos can be run either AC or DC.

My layout is run on DC current but I use no on-board sound and no command control... actually using the DC current has improved speed consistancy quite a bit. But I also remove the circuit boards too. Though my MPC-era locos all run just fine on the DC current too.

[FJ and G]

Bob,

The whistle can be turned off with a slide switch. I'm still wondering why no D.C. I can understand if instructions are for no A.C. but not the other way around.

[lionelsoni]

There is no fundamental reason why a modern locomotive would need to be restricted to AC, except to keep from blowing the whistle continuously.  Lionel apparently screwed up their design and, rather than fix whatever unnecessary vulnerability they designed into it, added the warning to their instruction manual.  I suppose it is also possible that the warning itself is a mistake.

[FJ and G]

Thanks; just thought I'd ask. If AC is rectified to DC, I figured that DC wouldn't hurt. I don't know the technical reasoning behind this but I'm not smart enough to ignore the warnings! Out of curiosity, is this true for most modern toy trains?

[Anonymous]

Dave,

              Don't try to run your docksider with a DC transformer.  It will destroy the circuit board that controls the direction of the locomotive.  Only run the docksider with an AC transformer.  The AC is rectified into DC by a rectifier on the circuit board.

 

                                                                                            Jim

[phillyreading]

Not that up on electronics but know some basic electrical stuff and from what I know about circuit boards the DC voltage may make the board act up. New trains tend to use electronic circuit boards extensively so there must be a reason to use AC voltage besides not getting reverse to work.

Lee

[FJ and G]

FINALLY, it arrived after 2 weeks and a complaint to eBay. I have not tested it but plan to soon and offer a complete review.

Finished reading the booklet that came with it and noticed that it warns NOT to run the loco with DC power. I happen to have a Lionel DC transformer that I had planned to use, but now having 2nd thoughts. I thought that the AC coming into the loco from track power gets rectified to DC.

So I'm perplexed.