Questions About LEGO Train Regulator

[Mr Hobbles]

I just built my first LEGO train set today, the 4512 Cargo Train, and I am very pleased with my choice. My next one will hopefully be 10001 Metroliner. :-D

Anyway, back on point. After about 15 minutes of playing with the assembled train, I took a screwdriver to the bottom of the train regulator to take a look at the electrics inside. I was surprised by the simplicity of it. 8-

[Hinckley]

...um...yes mr. hobbles, the train goes around in a circle, like magic!

;-) you're really smart. I can't follow your post. What I will say is the 9V trains are better!

[WesternOutlaw]

Mr. H: I've got a few transformers as a big fan of Lego trains. They definately transfer power at incrementals rates as you've indicated, rather than gradual power like traditional HO train transformers (or a light dimmer switch). I have not tried rewiring the inner-workings to change this, and not sure if you can. I'm a bit of a purist and careful with my Lego, so I would probably never try.

But I understand what your asking, just haven't tried it.

[SavaTheAggie]

It really isn't as noticable if you get in to MOC trains. Once you get into trains with 7, 10 cars behind the locomotive, the speeds decrease considerably, so the increments become less noticable.

Of course you can always add a second regulator to make up for that, but that's neither here nor there.

I can't answer your question though, I've never tried fiddling with the internal workings of anything electronic, at least not in that way.

--Tony

[Lego Amaryl]

@hinckley39: 12V trains are the best, not the 9V ones! ;-)

If I remember well, old 12V transformers offer a gradual voltage regulations. Maybe, you can use one of them, provided that you manage to "stop" the output at 9V (there was a way to stop it at 4.5V). Building a connecting cable between the two systems should not be difficult. Moreover, in this way you could also use the 12V fixed output to provide your city with illumination...

[Hinckley]

@hinckley39: 12V trains are the best, not the 9V ones! ;-)

:'-( I never had one of the 12 volts. All I know is that the 9V are better than the RC.

[Lego Amaryl]

I agree... Every time Lego changes its trains, it makes them simpler than before...

When I was a kid, I was really disappointed when Lego discontinued 12V trains and introduced the 9V ones. Unifying the electric system was a good thing, but why didn't 9V trains have automated switching tracks, illumination, and so on, like 12V? Did Lego think that kids were becoming less smart (or patient) to build such complex things?

[Hinckley]

And that's kind of what I thought with the RC trains. Do they think that kids don't understand DC?

I wonder if they run some ridiculous focus groups to come up with stuff like this. Maybe they made a deal with a battery company...

[Mr Hobbles]

Personally I think the 9V would be better than the 12V mainly due to the slightly more realistic track. Also, it wouldn't have been difficult to implement switch motors, signals, etc...I don't know why they didn't.

Anyway, I opened up my regulator and had another look and I don't think it would be too hard to put in a variable resister. I'm gonna shop around and see if I can find one that would be suitable. Maplin here I come. :-)

TheBrickster: Yes, I'm a purist too I don't like modified LEGO bricks, but you could hardly call it a brick. Any modifications wouldn't affect the outside, just the inside, so you wouldn't notice the difference. This is one modification I really do want to do, I don't like juddery start-stop trains. :-P

[SavaTheAggie]

And that's kind of what I thought with the RC trains. Do they think that kids don't understand DC?

I wonder if they run some ridiculous focus groups to come up with stuff like this. Maybe they made a deal with a battery company...

I asked Steve Witt about why LEGO was making the IR trains when the 9v trains seemed just fine, and he explained it to me this way: 9v trains plug into the wall.

You cannot, at least in the US, target a toy to a child under the age of 8 that plugs into the wall. Because of this, LEGO could not target nearly a third of their target audience, the 6-12 year old set, with 9v trains.

By removing the plug in the wall and going to full battery operation, LEGO could target the IR trains to 6 and 7 year olds.

I have other personal theories concerning IR Trains, but this is why, in my understanding of what I'm told, LEGO created the IR trains.

--Tony

[highlandcattle]

When I got this set at an age of nine I really had problems to getting it to work properly. The only reason I still use 12v volt is because of nostalgia and because I already have so much of it. It would be to expensive to change all that. But one can not deny that 9v trains actually run much smoother then 12v. Sure the system was way cooler but it was also waay to expensive for kids back then. I never got any other gift except from 12v electronics, simply because it was so expensive

[Brickthus]

Personally I think the 9V would be better than the 12V mainly due to the slightly more realistic track. Also, it wouldn't have been difficult to implement switch motors, signals, etc...I don't know why they didn't.

Anyway, I opened up my regulator and had another look and I don't think it would be too hard to put in a variable resister. I'm gonna shop around and see if I can find one that would be suitable. Maplin here I come. :-)

TheBrickster: Yes, I'm a purist too I don't like modified LEGO bricks, but you could hardly call it a brick. Any modifications wouldn't affect the outside, just the inside, so you wouldn't notice the difference. This is one modification I really do want to do, I don't like juddery start-stop trains. :-P

The circuit diagram of the 9V train controller is here:

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1559700

As you will see, it's a standard 3-pin regulator design, with the voltage varied by tapping off the resistor chain. Some people have substituted the regulator with a 5-Amp version, for driving trains with several motors, but some other components need uprating as well, as well as using a more powerful transformer at the wall.

The controller is designed so that the minimum useful voltage of just under 3V is at the first notch. LEGO 9V train motors under any kind of load don't do much below this voltage. It is possible to stop the dial at the point mid-way between 0 and 1 such that resistor R3 is shorted out, giving a lower voltage that will just move the motor. However, it's useless for all but 0-4-0 light engine movements.

If you want to avoid juddery start-stop trains, you really need a Pulse Width Modulation controller. The advantage of this is that the motor sees pulses of full power even from the lowest speed, so it has more torque when starting away from a station.

The disadvantage of using PWM with LEGO 9V train motors is that they buzz horribly. All that buzzing noise puts heat and vibration into the motor coils. The 12V train motors coped better with it, but the 12V train controller was more like a traditional train controller in that it uses a tapped transformer. Its supply is also rectified but not totally smoothed, so it gives the 12V motor the extra torque of a PWM controller.

I advise looking in The Complete Book of Model Railway Electronics by Roger Amos ISBN 1-85260-288-0 if you want to get further into model railway electronics. That book has 6 controller designs, auto start-stop, track circuits and more.

I personally use LEGO 9V train controllers only in the yard of my 9V railway. On the main lines I use a Maplin dual 30V 3A bench power supply (at 9V or less of course, usually set to 1.5 Amps per track). This gives smooth power, which the 9V motors prefer, and has worked well at 2-day exhibitions with trains running constantly at up to 8V 1 Amp (for a 4-motor train) all day. The switch-overs between trains take more current when both are working at the same time. The power supply is an analogue one with variable resistors for voltage (coarse and fine) and current limit. Not sure if you can still get those or whether they're all digital LED displays now (harder to read with varying voltages and currents).

I don't mod more than I have to, but anything beyond the feed wire to the track is fair game (cut a 9V lead in half and put 12V plugs on the end :-) ). I reserve the right to make LEGO train electronics what it should be in my quest to build a realistic 8mm scale model railway out of LEGO :-P

Mark

[Mr Hobbles]

Ahh I see, so instead of changing the resistor, it adds more onto a resistor chain. This makes sense.

I take it PWM works pretty much the same way as pulse jet engine, ie. instead of a constant low speed force, it's several spaced pulses of a higher speed.

I'm not all that interested in model railways, I just want slightly smoother train operation. I'm considering heading home and fetching my Dad's old 12v model railway controller, it should do the trick. Although I might still make that modification to the LEGO controller. :-)

Thanks for the info! :-D