Voltage Reducer for downgrade

Hi Frank, there is three ways to do this voltage reduction thing. You can use DCS, but I'm sure you know all about that. The trick you are looking for though is something that will cut the voltage on the down grade of an elevation.

On an up and down loop like going up and over a bridge with the train running in the same direction you can use two transformers. One power source will be adjusted for the up grade speed and the second could be set for the down grade speed. Of course each transformer would have to power it's own block.

The third thing you can do is keep the two blocks but use one transformer. The up grade will go directly from the power source to the track but the down grade could go through a dropping resister. You will have to play with the value because every engine is a little different. I would start with a 25 watt five ohm resister and step it up by one ohm until you reach the desired down speed. Mintronics has a six port rotary switch that you can use for this set up and Radio Shack has the proper ceramic resisters. I bought fifty watt 10 ohm resisters from them and some 25 watt resisters in 7 and 4 ohm. two 10 in paralle, or side by side will make a 5 ohm, two 7's will make a 3.5 ohm and two 4's will make a 2 ohm resister.

 

The best way to do it though would be to have a relay N/O contact trip, or close when the train is at the bottom of each grade to provide the up power and at the top of the two grades you can have another relay trip with the down power. Each relay will have to have a second set of contacts that are N/C. This N/C contact will provide path for the drive voltage to the associated realy on that grade. Thus when one trips the other will lose it's drive voltage returning it's track power contacts back to a N/O state. This is so only one transformer can be applying power to a grade at a time.

 

Of course you have to adjust both up and down voltages for every engine and length of cars they may be pulling. I think Dale H has some drawings for this configuration on his web site. I'm sure when he sees your post he will be drawn to it. He loves these kinds of projects.

Dale M is also big on this stuff but I think he will probably suggest you do it with DCS / TMCC as I did.

 

I am not near a scanner at this time but if you like I would be happy to make a drawing up for you and e-mail it ASAP.

 

Now go have fun.

The Passaic, Raritan, Neshaminy, Delaware & Lehigh has a similar problem. We achieve an over/under with both main lines on grade – one goes down and the other goes up. Trains tend to slow on the upgrade and race on the down grade (even though the grades aren't that long).

 

I used a pair of  pre-war Lionel Variable Resistors. (I think they're No. 90.) Regular voltage goes to the upgrade section. The level section and the down grade get power through their respective resistors. 

 

Performance is pretty good. The nice thing is that the voltage can still be adjusted for each section based on the engine(s) and how they perform.

 

And it was a relatively inexpensive fix.

 

Another way that was explained to me is using a bank of high current diodes and utilize the fixed voltage drops of the diodes. Can either have a "tap" of 1.4 volts (pair of diodes) or .7 volts (single diode). Use a selector switch since every train will need a different voltage adjustments. I bought the diodes once but never completed the unit. I was even going to have printed circuit made.

Cool. thanx a lot guys!

F

Many of Lionel's earlier transformers had seperate outputs for each handle so that you could connect the main part of the layout to the higher voltage out put and the down section to the lower voltage output and there would always be 4 volts differential.

 

An example is the type RW where the knob varies the voltage 9 to 19 on A-U posts and 6 to 15 on the B-U terminals. 

 

 

good luck and happy railroading,

Don

You can use a diode voltage dropper as described here. Either use 25 amp bridge rectifiers or 6 amp diodes,described here

 

http://www.jcstudiosinc.com/BlogShowThread?id=413&categoryId=

 

There are a few ways to do it. If the train only goes one direction it can be done without a relay but rollers will jump the power block center rail causing erratic operation. Relay operation would be better. The best set up would be 2 relays at the beginning and end of the grade so power is reduced according to engine position,but it could be done with one if the train lenght is fairly consistent. With relay(s), the center rail need only be insulated if 2 or more train run on a loop,otherwise only 2 short outside rails need be insulated if 2 relays are used.

 

Bi directional operation can be done also with extra relays but is a bit more complicated.

 

Resistors will work but I do not recommend them for safety issues. A short on the track can make them expend far over their wattage rating.  They will also act according to Ohms law and will not drop voltage evenly for all trains since some have more resistance according to make and era.. 

 

Using the multi tap transformer idea will work only if roller jumping is eliminated with relays. Roller jumping on 2 PW transformers set at different potentials can short out the secondary windings and would not be breaker protected.

 

Dale H

On something like the V, Z and ZW, you could run THREE different votlages from the same transformer.  Level areas one output.  Upgrade one output.  Downgrade one output.  Say A to level, B to up, C to down.  For each section, you need track pins in the center rail, and a lock on.  NON-U wire would go to the center rail.  Outer rail will go to U. Adjust voltage to each for smooth running

 

If you have a Cab 1, with three different PowerMasters, you could do the same.  Program 1 for level, 2 for up, 3 for down.  Again, not-U goes to center.  Adjust for smooth running.

Instead of resistors you could use back-to-back diode pairs in series to achieve the desired voltage drop.  For uni-directional operation, this could be a simple solution.  It would also not require an extra transformer, just the isolated center track with sufficient diode pairs to drop the voltage to your desired value.

 

As Dale says, this works best for fairly consistent train sizes.

 

For bi-directional operation, you're into more complicated control.