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Electify Your Train Switches

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#76 re465


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Posted 21 April 2012 - 10:49 AM

View Postdlp4341, on 03 August 2010 - 07:35 AM, said:

Posted Image
simplest solution would be to get back the 70026, 12V Remote Control Switch Motor
as 9V version ;)
I have tried too a lot all kind of solution, 90-100% of legos mades.
With/without PF, 1 micro-motor too!
Go and check out, maybe you find some ideas.

Edited by re465, 21 April 2012 - 11:09 AM.

#77 Hanso


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Posted 04 January 2013 - 06:57 AM

Hi Folks,

I am new to this Forum, so maybe I am telling you nothing new. But I have also created an automated switch, in two flavours:

1) PF controlled

2) Mindstorms controlled (as you can see, it has also a feedback mechanism)

Wissel Aansturing (Mindstorms).jpg

Together with a small group of colleagues, I am building a fully automated train layout. We will use about five NXT controllers, and the software will be written in the programming language Microsoft C#. Two trains will run in parallel, the computer should prevent collisions.

We have been at Lego World 2012 in Zwolle (The Netherlands) with a first version of the train layout: it runs with one train only, and the switches were not functional yet. You can find an impression here: http://www.youtube.c...SiouxNETonTrack.

Edited by Hanso, 04 January 2013 - 07:11 AM.

#78 Mark Bellis

Mark Bellis

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Posted 05 January 2013 - 03:57 PM

The new LEGO PF Servo Motor will be out as a single-item set in March this year.
That means this simple solution will be available without buying too many 9398 Crawler sets:

Posted Image

Just a 9V supply and a 1-way switched supply is enough to drive the LEGO PF Servo Motor as it returns to the centre position when C1/C2 power is removed.
I drive the servo with a standard PF battery box and pole reverser switch (one way and centre only, the other way disabled with plates blocking the lever).
I tested it successfully with several lead added so I know it will work 2 metres from the control panel.
The PF pole reverser switches make a control panel quite easily and the extra little switch allows the user to set the polarity for pairs of facing points (which is why I petitioned for it to be added).

In the picture the mast foot clamps the point slider casing to the motor mechanism, keeping the end of the rack in the lever shoe under high torque.
The lever raises the red piece when the point is set curved.
The mechanism is designed to minimise the profile close to the track, to accommodate large train overhangs that would knock a yellow lever out of place.
This solution is designed for best reliability in places you can't see or reach over a 2-day show, such as a fiddle yard under the station (hence the stanchion).

The NXT would not provide more than C1/C2 with the standard NXT-to-PF converter lead but the PF lead could be hacked to add a 9V supply for several servo motors if necessary, or a bridge rectifier could be added to each lead if single motor sub-system autonomy was required.
I dare say an easier PF Servo Drive solution for the NXT may present itself in the future.  I can see NXTs driving PF Servos being popular for robotics.
For the moment the easiest no-mod NXT solution is to use a PF IR Receiver and for the NXT to drive it (or several of them) with an IR Link sensor (which are on January sale at LS@H).

More mechanism pics in this folder.

This is simpler than my previous solution, which used either PF, monkey or 71427/43362 gearmotors but more gears:
Posted Image

This previous solution fell foul of a sticking switch point.  It stuck just a bit more than the torque of the white clutch gear.  The clutch gear would eventually wear out, which is why I went for the servo motor solution instead - more torque, no wear-out mechanism and open-loop deterministic position - it ticks all the boxes!

Mark J E Bellis - 8mm Scale LEGO Railways, Scenery and Technic. Visit My Brickshelf
Posted ImagePosted Image  Posted Image

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