Hello All

Looking for advice on adjustable resistors. Ever since I read about them in Carl Weaver's book,
page 67, [Brawa 6154 - 0-100 Ohm/5watt] ...I have been wanting to use them.
Now that I have a good reason to use one, and I am not sure which kind is best.
A search turned up a ton of them, http://binged.it/151n1Sk
but there must be something from a local electronics parts shop that should work.

So today I went to Abra
http://www.abra-electronics.com/

I thought of just using a wall dimmer, and when I suggested this to the manager at the electronics parts shop he said, yes that would work fine, but it will make an electrical buzz. Does anyone have any experience with this? Wondering if other simple old radio volume controls might work. I don't want to use a separate transformer just for one area of track. Basically I want to be able to adjust/slow down the speed of trains as they come into the station using automatic train control. I am new to soldering and understanding schematics, but learning a bit.

- Mark

FYI - I managed to get the three trains running nicely on the loop with one siding using M-5167s.
I have yet to make some adjustments.

Edited by user 24 August 2013 22:45:14(UTC)  | Reason: title changed to include "analog"

Hi Tom,

Thank you for the advice. Yet, this is for a analog layout.
What would you do in this case?

Good to keep in mind when using digital.
So far my digital experience is with carpetbahns using a 6021 control unit.
Would they respond this way when running in conventional mode?

The idea of a dimmer or a control knob is to be able to adjust the speed as locos come into the promenade/station, depending on the loco.

- Mark



Mark

Excellent Tom,

I have been burning the midnight solder with some new ideas I've found, so this might be really fun to try.
While I do have a number of extra trafos, I think it would be overkill for a small portable layout.
I want the girls to be able turn the main trafo off and have everything stop. That said, I will have a kill switch on the control panel too.

I have however come across the Viessman 5216 slow train control.
Anyone? have experience with this?
http://www.rocousa.com/v...iessmann_5216_detail.htm

It looks like a good alternative and could be used at some point for digital...
... and I guessing this should not be a probelm to use for 3-rail AC?

- Mark

FYI ... My first soldering experiment now gives me an LED dimmer, and secondly, I salvaged some old electronics have cobbled together a simple incandescent light dimmer without the need of using a secondary trafo. I will be checking to see it doesn't overheat; will have to look calculate that still.
Even so, I may still use an extra old trafo, depending on the number of lights I use.

Hi Tom and all,
After reading the brochure for the 5126 (thanks for the link) I am starting to wonder if a schematic to make one is around.
WRT to the Diode set up, was there a link to a full schematic and parts list? I am not really a electronics whiz, but I can follow a schematic and build it like a puzzle.
- Mark

Hi Tom and all,

I went to Abra electronics again today and asked him about the Diode set-up.
He sold me 3amp diodes, however, for Marklin analog it requires only AC, does it not?
Once the current goes through the Diode chain, he told me it changes the current to DC.
I am a novice at the circuit building game, so any guidance would be helpful.

Did they say anything on Stummi's forum about slow train control with AC?
I looked up the thread with google translator and it seems [if translation is correct] that he was looking for slowing down his DC tram.
Link to translated thread: http://bit.ly/18Jh2DV

Question then:
Does anyone have other suggestions for the best way to create a circuit to slow down an analog Marklin AC loco step-by-step, for use in automatic train control.

My number one complaint about the Viessman 5216 is having to concern myself with heat production and having to mount it face up as per the recommendations in the PDF, instead of under the layout where it could have been tucked out of the way.
This would not be so convenient for a portable layout, and would take up room on the control panel.

I did buy a standard wall dimmer today for 600W light which I will try tomorrow.
Guessing it may not be sensitive enough for the gradual change. Overkill?

The other problem with a wall dimmer is that it will not work for digital, as I'd like to have that option.

And even if this does work, my idea was only to use it to tweek the current supply for different locos that require different power needs.

The other idea about using a alternate trafo is ok, (I have a bunch) but not the best option, since I want to have the person controlling on this small layout/loop with only one control. For the girls especially, worrying about two trafos for our main control seems an unnecessary complication.

Any suggestions are welcome!
Mark

Dimmer *may* look like it is working for a while, but I would be very careful.
A dimmer will introduce sharp edges/ high frequencies in the power supply to the motors.
They **will** not like it if subjected too long to that kind of treatment: the connections inside the motor (especially on the commutator) could overheat and destroy it.
Tom's suggestion of anti-parallel diodes is a very good one, it is simple, inexpensive and it will not destroy or overheat your motor.
Simplicity is the mother of reliability too.
When you go to digital, all you'll have to do is to remove a few 50 cents diodes...
Plus my two cents of advice..
Cheers

A diode is like a one-way door. By putting two diodes in anti-parallel, we have a one-way in-door and and a one-way out-door - thus we allow traffic in both ways (AC), but we slow it down a bit.
If one diode blocks, then the other will allow current to pass through. The diodes only convert about 0.6 V into warmth, but allow AC to pass through. And that's the desired effect: reduce the voltage a little bit.

With purely analogue locos, you could try just one diode. This would convert AC to DC, the effective voltage would be 50%.

Using pairs of anti-parallel diodes allows to reduce the voltage in smaller steps - and it should also work for locos with decoders.

For analog use, if you wanted to have separate control of trains entering and leaving the station, I would simply go with a separate transformer and isolated sections for the station tracks. If you wanted to go one step farther, you could set up a series of switches, so that you could select either the mainline or station transformer for control of each track. This would mean that open tracks could be powered by the mainline, while tracks with incoming or departing trains could be controlled by the station transformer. You would have to make sure that the switches would prevent the two transformers from being connected to the same track at the same time.

If you have four tracks in your station, you could use one transformer and control which track was in use through signals or you could break it down into two or more transformers, up to one transformer per track.

One last possibility. Taking a 240V transformer and running it of 120VAC in Montreal would give you an effective way of controlling low speed movement. The only thing is that I doubt that you could initalize a reverse pulse, and the locomotive might take off at high speed if you tried.

Converting your loks to digital and using either your 6021 or a new MS/CS would enable you to control each train individually, making a second transformer not necessary.

Regards

Mike C

Thanks Mike and Tom,

Using a 240V trafo is a really interesting option. I have an old 220V "Super" which is ok since I am only using our analog locos for this arrangement.
I had no idea they would run well that way.
Have you heard of other Marklinists doing this?

At some later point I may combine both secondary trafo with the diode arrangement so I can tweek the levels appropriate to the power consumption of the respective locos. I also like your suggestion about the main and secondary lines.

This arrangement is our very small Madchenbahn in a 3'x5' layout. So only one siding.
I will post results when I get the slow train arrangement in order.

Thanks again gentlemen.
- Mark

Maybe I am late to this subject, but anti-parallel diodes is EXACLTY how I control my trains on a rather big analog layout!

Basically the power to my tracks is fixed, from several different trafos, depending on sections (going up, going down, hidden, parade, etc)

All locomotives have 0, 1, 2 -or however many pairs of diodes needed inside them, in series with the motor. Thereby adjusting the speed of each loco, in regards to the fixed track voltage.

Lastly, series of relays change the fixed power to the tracks, swtiching in "None" or several pairs of parallel diodes, so as to make "soft acceleration" possible, in front of visible signals on the track (and also for slowing down in difficult sections in hidden areas)

It´s very SIMPLE, RELAIBLE and CHEAP -as already mentioned by a few here.

In the 7 years (I think) that I have used the system, I have never burned a diode. (I think each one is 2mm diamter and 4mm long. Maybe the 5W units H0 talks about). -And I have had several derailments and short-circuits. I have even had the solder of the diodes melt, because of shorts(!) -So they can even work like fuses... ;-)


BTW -and almost off topic; Here´s a rather old drawing of the braking-system. It´s a little outdated (as the system has been modified a little) -but I think it shows the main idea;

This looks great hxmiesa!
I have yet to implement the diodes, but have things set up with separate feeds to isolated track to try it.
The one problem I expect is that, since our "Mädchenbahn" layout is only 3x5 feet, I have very little space to slow down and speed up.
One standard length M-track per drop in power.

Getting a bit off-topic, but to update, I regret somewhat having chosen industrial curves, even though the locos we are using are small. .... I have an incline with an industrial curve and those "one-sleeper" tracks used to make up space are a pain for derailment...
once I work out the bugs, the diodes go in.

Today we had day one of the train show in Montreal, and we managed to get things running with 3 trains, catenary "game" of one train obeying the signals manual where the other two run automatically, the incline and tunnels. The response was really good for a half-built layout. M
ore later on this. This is a continuation of this topic:
https://www.marklin-user...aspx?g=posts&t=27100

- Mark

These diodes are used inside some locomotives to permanently reduce the speed of individual locos.

The diodes used to slow down trains in front of the signal are not shown on the plan (these would go between red and A, B, C, and D on the plan).

Sorry, no drawing. The inside of the locos is really simple; The diodes are in SERIES with the motor, after the direction-change-relay. More modern Delta and Digital locos are normally so well-behaved (=slow) that no additional diodes are necessary.
Power from the track must reach the decoder (or direction-change-relay) without passing through diodes.
Of course this setup makes normal analog direction-change impulses impossible on the braking-sections, if the signal is showing Hp0. (Anyway its not needed)