Conventional speed control

Others will weigh in, but I don't believe that light dimmers will handle the load. The overarching factor is what is the rating of your transformer and the current load of your locomotive.

Gilly

Speaking from experience, traditional light dimmers like you get from Home Depot wont work.

What are you trying to achieve with these block sections?

Multiple trains on one track?

Automatic speedup/slowdown for grades and curves?

I just use diodes,described here,I make a complete throttle with bridge rectifiers

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

Dale H

AC dimmers for lamps require 120V AC line voltages to properly operate the triac semiconductor that "chops" the line voltage to reduce the effective voltage.  Controllers for model trains use the same triac circuit but it operates at the lower AC voltages out of train transformers.  Could one modify a Home Depot lamp dimmer to operate at lower train voltages?  I wouldn't be surprised if someone hasn't done this but I see it more as a DIY exercise for personal satisfaction as it would not save much money, time, etc.

Answer Flash's questions about what this is for in which case I'd bet Dale's diode method will turn out to be the simplest and economical solution.

You could use engines that have speed control in conventional operation, such as MTH's PS2 and PS3 engines.

Here is a pic of bridge rectifiers used as voltage droppers. (In center ,click on photo to enlarge) The train accelerates in 10 steps in conventional. The whistle and bell also are blown automatically on start up and at crossings. Very easy to slow a train down hill or on a curve and add extra voltage uphill,using a relay and the insulated rail method.

 This is a simpler board for a trolley that goes up and down a grade then crosses a train loop in 2 places. 6 bridge rectifiers provide voltage differences for flat,uphill and down hill,about a 6 volt spread.. Also provided is soft start,routing for 3 trolleys and timed station stops along the route.

Dale H

Dale, just looking at that board and then hearing "easy" seems a contradiction!

Jeez! it even looks like a pin ball machine!

I worked on pinball machines when I was in high school, it does look like the wooden decks they used with all the relays and stuff on them.

I tried this and it was problematic - see below.  But first, I run mostly Legacy and PS3 engines any more, in conventional, and they all have cruise that works well.  Some early Odyssey versions had an annoying "surge" in speed at times, and they and PS2 a propensity to sometimes "fall out of cruise" and slow dramatically if the pull up a long slope got too hard, but the most recent systems seem flawless. I recommend this route.

I run only conventional locos like BEEPS and Lionel 0-4-0 shifters on my BEEPWorld loop, which is too tight for most Legacy locos.  I tried making a three separate blocks fed with resistors in line to vary voltage so as to get: full voltage on the uphill ten foot section, about 20% less on the downhill ten foot section, and about 10% less on the other, mostly level sections, or something like that.  It turns out I needed resistances around 2 ohms or so to do it and they needed to be fairly large each (5+watts) and they got very hot.  And the resistances and all that would work for one loco type (a BEEP) weren't at all ideal for another rtype  (0-4-0) shifter: I would have needed resistor sets for each loco.  I think diodes would be a better way if I did it again, but I just connected it all back to full voltage and learned to like the slowing uphill and rushing downhill.  It's an acquired taste, I think.

Command operation and cruise control.

I dont use resistors,I use 30 amp bridge rectifiers as droppers. Using 2 relays as block detectors  one or the other is on when the train is on the respective grade. So when a train goes uphill,voltage is full throttle. When train goes downhill voltage is - 6 volts from the throttle. When train is on level surface,voltage is - 3 from the throttle. there is no roller jumping,only outside insulated rails need be insulated on the grade portions. Voltage drop is adjustable in .6 volt increments. With 2 more relays,system can be made bi directional. 

Trolleys can be done with no relays,just by blocking center rails and connecting uphill and downhill blocks to the voltage dropper. .Per the diagram 5 bridges give about  a 6 volt spread.

Dale H

Actually the plywood is from an old coin op gun game I scrapped for parts. Really good furniture grade plywood,better than anything Lowes sells.

Dale H

I just knew this was a pinball in it's earlier life!

I copied this albeit small photo from this thread to show a different implementation of the diode-dropping method. John2290 used a computer controller and relays to selectively switch in different diode-drops from a fixed starting voltage.  He ended up with 4 voltage selections.  So if you're controlling just one engine per track, then the alternative idea here is to change the voltage to the entire track (rather than isolated blocks).  Sensors on the track would signal the computer when to flip the relays to alter the voltage.  Of course if your rails are already isolated into blocks you can skip a step.

Dale's non-computer implementation has many more features than what the OP is asking for. John2290's computer implementation has many more features than what the OP is asking for.  The bottom line is the diode method at its core works...but imagination and human nature conspire to add bells and whistles.

The only difference between mine and Johns application is that he uses a computer for logic and timing. I use relay contacts, a repeat cycle timer and interval timer for logic. John uses a software program to make adjustments. I make adjustments by turning 2 dials on the layout. One dial adjusts acceleration rate and the other dial adjusts time between train stops.

Either approach is fine,I just choose not to involve a computer. I have a large quantity of relays and timers on hand and can make up a circuit for most anything I want to do within reason. As complicated as my boards seem,it is really simple switching with relays and timers,capacitors and resistors.

For the original question of speed adjustment up and down hills. Really it can be done with the diodes as droppers and 2 relays for a train,no relays for a trolley or train without passenger cars.

Dale H

I didn't use and control, etc.  My original concept with the resistors was a "static" (no moving parts of changing feed lines) system in which, say, if you set the power supply to 16 volts, i would feed that to the uphill portion or the tracks, but a resist in line with the downhill portion would see it got only 12 volts or so, and one half that resistance would see that everything else go perhaps 14V.   I used resistors 'cause I had a big bag of 10 W resistors from 5 to 20 ohms - not sure where they came from but when you have them just sitting there in a bag . . . 

As I said, this worked, after a fashion.  With a bit of fiddling, I found a set of resistors that did this so they kept a Lionel 0-4-0 chugging away at near-constant speed up, down, and around.  No relays or control.  What happened when the loco crosses from, say, the 14 V section to a 16 V section?  Nothing dramatic.  Electricity has a way of working it out.  But as I said, when I'd run another loco, say a BEEP, I'd find it overreacted, and I would have to change the resistor values.  I just didn't want to fillde with it that much.

Just not worth the trouble.