Skip to main content

Hi! New to this forum along with being new to O Gauge. I have been following some tips on using diodes to help limit amps to the motor or motors. I have two Lionel locomotives I want to do this on. My first question just to be sure! Diodes go on one wire to the motor? Not on both wires? My second question is one locomotive has two motors. If you only use one wire of the two to each motor, would I put diodes say to the yellow wire on one motor and diodes on say the blue wire of the other motor?

Locomotives I want to do this on is a Pennsylvania RS11 part #6-28553. I think it was manufactured in 2007.

The other locomotive is the Berkshire 2-8-4 that came in the Horseshoe Curve Set part #6-30180. I think the Berkshire only has one motor. I haven't removed the shell on that one.

Operation is conventional CW-80 transformer.

This is a shelf layout over my N-Scale layout. I have provisions in place if there is a derailment. I don't like my trains going 100mph. The other reason is my sounds don't start up until the locomotives are really moving.

The Berkshire has Rail Sounds. The RS11 I put in a Electric Railroad Co. sound board and speaker. One thing the RS11 does since the install is when traveling at a slower speed, if I hit the bell button on my CW-80, the locomotive stops and goes into reverse. Now if it is really humming along and the sounds kick in, the bell acts as it should and train keeps moving.

Last thing, I see some use 6 amp diodes and some use 3 amp diodes. The only ones I have found are 1000V!

If anyone can help guide me through my questions I would be very grateful.

Thank You!

Rich

Original Post

Replies sorted oldest to newest

The diodes are in pairs, back-to-back.  They go into one motor lead.

 

Since 99% of the time the motors are in parallel, you can put the diode pairs in series with the common feed, that way you only need one batch of diodes.

 

You can probably use 3A diodes unless you're pulling some long consists, but some folks like the security of 6A diodes.

 

You can also use a bridge rectifier to replace four diodes, sometimes this is a bit more compact.  Connect the + and - pins together and connect the ~ pins in series with the motor lead to use the bridge.

 

Here's an inexpensive 6A Bridge Rectifier that would work well.  In addition, Digikey has very low shipping costs for small orders via First Class Mail, usually only $2-3.

 

 

 

Thank you gentlemen again for the help. I did order the 6 amp rectifiers. My shelf layout is perfectly flat and I should run no more than 7 cars and a caboose. My siding won't hold anymore than that. I run the RS11 one direction for a while then park it to run the Berkshire. I am hoping to only need one per locomotive but until I get them I won't know. I should have them tomorrow. I paid extra for 1 day shipping. :0  I can't wait to do this project. I may jump on here this weekend and pester everyone. I am sure I will run into something.

Rich

Last edited by RioGrandeDude

Well I have 3 in there now. Could use a couple more but it has got better. I have them linked together coming in to the ~ near the positive and out near the negative. Then to the next rectifier near the positive and out near the negative and so on to the next rectifier. I didn't know if it mattered, I just looked at it as in and out to make all rectifiers linked the same way. In near the positive on the first rectifier and out near the negative on the last rectifier.

I will try it with the three for now. It is lots better than it was. Maybe I could put a couple more on the other motor lead.

Originally Posted by rockstars1989:

I  must be missing something.I don't understand this subject.Your trying to slow the engine down?Why not just dial the voltage down on the transformer?If command environment,use the speed limit feature or dial it down via the cab remote???Nick

The biggest reason is to prevent "jackrabbit starts," most transformers actually start at a voltage that results in fast-running trains, which looks unprototypical.  Another reason is to have more track voltage at lower speeds for brighter lights and more current to smoke resistors.

 

Originally Posted by jimmysb:
Why would this reduce the speed on a pullmoor motor.   In my experience when you press the whistle button (half rectified dc) the train goes faster not slower.   Also is it safe to run pullmoor engines on dc won't they have the risk of overheating if stalled.

The difference is not the DC offset, but rather the boost winding in the transformer supplying more voltage to compensate for the PW whistle motor.  Diodes won't boost the voltage.  Also, the stuff we're talking about all has can motors, so characteristics of a Pulmor motor is not exactly an issue.

 

Note that when you use back-to-back reverse polarity diodes in an AC feed, it does NOT rectify the current to DC, it just drops the AC voltage around .7 volts for each diode pair. 

 

FWIW, most Pulmor motors will run fine on DC, however, that's a different topic totally.

OK! I finally got what I was after. I have 3 rectifiers in the Berkshire and 6 rectifiers in the RS11. Lights, sound and smoke is so much better. It's pretty cool. It is amazing what you can do with a couple average locomotives to improve what the factory should have taken care of. Oh well, I learned something new and what the heck, I'm having fun with it. Thanks again guys for ALL the help. I hope I can help someone like you did for me. After all, we are all here for the love of the hobby.

Rich

Post

OGR Publishing, Inc., 1310 Eastside Centre Ct, Ste 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

×
×
×
×
Link copied to your clipboard.
×
×