Slow it down.

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 guys both for helping me out. It is so nice to have a place to go for help. This O Gauge stuff is very new to me.

Would this work? Being 10A, would I still possibly need 2 for more voltage drop?

http://www.digikey.com/product...41-1367-5-ND/2074832

It would work fine, but it's massive overkill.  The 6A one I posted the link to is cheaper and more than sufficient for the task.

 

Dale, you're certainly free to your opinion, but I can't imagine any single engine pulling anything close to that.  Obviously, it'll work, but it's bigger and a bit more expensive for no gain, IMO of course.

 

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

I'm sure you'll be fine with those.

 

I just got done running the trains. It will probably only take one rectifier for the Berkshire. It may take two for the RS11.

I am really starting to like O Gauge. The smoke and sounds is real nice.

Rich

Next, we'll introduce you to command operation.

 

OK! Got the shell off my Berkshire. I have a red and blue wire coming from the board labeled "Motor" going to the motor. Correct me if I am wrong, but I need to place the bridge rectifier in line with the blue wire between board and motor?

May the 4 prongs be trimmed in length?

Rich

Correct, just wire the + and - together and insulate them from any other connection.  Use the other two ~ leads in series with either motor lead.

 

Oh My!!! What an improvement. I am so happy right now. It worked like a charm. Thank you so much for helping me through this. I can't thank you enough.

I think it will take two rectifiers for the RS11. I will try only one and go from there.

Rich

It is going to take more than one rectifier for the RS11. Do I install another one on the other motor lead or do I need to stay on the same lead as the rectifier I have installed now? Can I install more than two rectifiers?

Either lead is fine, wherever it fits.   You can put in as many as it takes to accomplish the desired speed characteristics.

 

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.

Like I said, you can use as many as you need.  Also, the orientation of the ~ terminals makes no difference, with the +/- connected together, the packages are symmetrical.

 

So both leads at the same time can have rectifiers in series?

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.

 

Yep, not a problem at all.

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 diodes in series with a motor do not reduce its speed, they reduce the Voltage going through the motor by about 0.7 volt per diode, so he has to give the loco a higher voltage for a given speed.

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