Subject:
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Re: 12V and 9V on same track footprint
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Newsgroups:
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lugnet.trains
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Date:
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Tue, 1 Apr 2003 18:45:36 GMT
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Viewed:
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1160 times
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As you say this is hardly possible.
We did that in 2001 (www.hot.ee/sonnich/lego/ - under galleries you will
find the Baltic Train Event), and found it hard (impossible) with curved
rails. We used straight rail for a "border" station between the systems.
I have been working on a project to make one engine work on both systems, it
seems possible but hard.
Some ideas:
1. should use the most powerfull source
2. should NOT run if polarities are different
3. minimum voltage drop
I made a design for that but never had the time to use it. Mail me if you
want the schematic
The last is hard to overcome, I use diodes (drops 1.2 volts). It solves
problem one though
The output was planned with a H-bridge, I never had the time to search for
such one, but the time for (step)motor drivers.
Part 2 is solved with NAND gates.
There is another problem here - if you have both powersupplies on, there
might be an offset (they are galvanic separated from the mains, but it never
works 100% (noticed the electric shock you get when you connect the TV
cable?) - the power from the offset might be little but present and
eventually enough to fry semiconductors, which could give the system a short
life :-(
The solution is to connect the 2 grounds, but that means opening the
powersupplies. Another solution is using 4 resistors to connect in one
point. Not sure how the last part will work.... might give it another offset
but at least less.
The problem is also to make the system run on very low voltages. Usually
there is never less than 3V out, which is just enough to make CMOS works -
but that is 1.8V if we have the 1.2 voltage drop.
To detect this I use optocoplers. It was the best i could think of as it
will always give a signal if there is something present. There must be a
better solution, but the problem here is we don't really know what is there
when it off and so.
I built 7-wide as it works on 12V tracks and looks "right".
Andy Stringer <Andrew_D_Stringer@hotmail.com> wrote in message
news:HCnLLw.599@lugnet.com...
> I've also been considering (as I believe many people have), the ways in
> which 12V and 9V trains might run together. Slotting the 12V conductor • rails
> into 9V track seems the most obvious solution, but there are two major
> problems; it doesn't work for the curves and the points are never going to
> be electrified without some serious chopping of conductor rails (has • anyone
> tried this?).
>
> The other possibility seems like a non-starter at first - electrify 12V
> rails for 9V use. This would possibly be a better solution in my opinion, • as
> I prefer the 12V point geometry (although it's no good if you like to • build
> 8-wide). Other than using sticky copper tape (well known to slot car
> enthusiasts) I can't think of a valid way of doing this.
>
> Which leads us back to adapting the 9V motor for 12V track - maybe Ben
> (Beneke) could manufacture us some? (I've actually had the pleasure of
> meeting Ben and his adapted motors are very neat).
>
> Andy
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Message is in Reply To:
 | | Re: 12V and 9V on same track footprint
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| I've also been considering (as I believe many people have), the ways in which 12V and 9V trains might run together. Slotting the 12V conductor rails into 9V track seems the most obvious solution, but there are two major problems; it doesn't work for (...) (22 years ago, 1-Apr-03, to lugnet.trains)
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