# Skip a Stop



## toddalin (Jan 4, 2008)

With the exception of one loop, all trains on the T&LB get to rest as much as they run (continuously for hours on end). The loop that doesn't stop includes the grade (<2%), and even pulling short trains, this loop tends to burn out the motors on my USA Trains.

So I decided that this year we would add a stop at the aerial tramway to let passengers load/unload. This is accomplished using a reed switch to detect the engine at the tramway, 556 chips, to handle the timing, and relays to handle the current routing. A second platform was added in Lizard Lane and the trains will also stop here.

When the train passes the reed, a relay cuts power to the block and a second relay kicks in simultaneously sending reduced voltage to the track (for an adjustable period of time) so the trains slows before stopping with the coaches at the platform. The trains then wait for up to ~1-1/2 minutes (adjustable) before another relay kicks in (for an adjustable period of time) again sending reduced power, but a bit more than during the slowing relay, so the trains leave slowly then speed up when the system cuts out (the main relay is normally closed).

As an added extra, another relay is used to sense the track voltage and when a certain voltage is exceeded (adjustable), the trains will slow faster so as not to have the lead coach overshoot the platform at the tramway.

Finally, because the platform in Lizard Lane is located in the electrical block next to that being protected, trains would not stop when proceeding in one direction because they will travel beyond the protected block before coming to a stop and this next block would be live. (These trains would slow for a moment then speed up and proceed on). So in this case a relay/diode detects the track polarity and if the trains are heading in this direction, this platform (i.e., reed switch) is ignored and the trains would proceed on to the tramway.

I had everything working and Linda was watching it and asked, "Are the trains going to stop every time?" 

OK, how can we make the trains only stop every "so many" times though the station?  

Then it occurred to me, when the trains power back up from the stop, this triggers another 555 chip with a period adjustable for up to ~3-1/2 minutes. This opens the normally closed relay contact between the reed switches and circuit board so the reeds are ignored until this 555 chip times out, again closing the relay and activating the reed switches. So the trains will ignore the reeds for up to 3-1/2 minutes. But the time can also be set for just a few seconds so that if two engines with magnets were running in a consist, the second magnet could be ignored rather than stopping the train again while still in the station.


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## chuck n (Jan 2, 2008)

I'm not big into electronics, but could you use a group of relays, where each time the engine passes it trips the next relay until the last one stops the train? 

Chuck


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## toddalin (Jan 4, 2008)

chuck n said:


> I'm not big into electronics, but could you use a group of relays, where each time the engine passes it trips the next relay until the last one stops the train?
> 
> Chuck


 
Yes, it could be also done that way. The results would be a bit different, but it could provide the desired effect.

This will result in more randomness, because on occasion, the train will wait for another train at the X-ing and this will change the timing between the two stations so the trains may stop at one station or the other depending on... If you daisy chain the relays, the results would always be the same.


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## SD90WLMT (Feb 16, 2010)

Can you explain how the ''Space & Time continuing Theory" works here...?

Is it possible in the overall randomness of it all for two trains to occupy the same space at the same time..?

......what prevents a crash in this setting..?

Just wondering outloud!!!
....Dirk...


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## toddalin (Jan 4, 2008)

SD90WLMT said:


> Can you explain how the ''Space & Time continuing Theory" works here...?
> 
> Is it possible in the overall randomness of it all for two trains to occupy the same space at the same time..?
> 
> ...


 
The Tortoise Bump Accident Sentinal System (Bump A.S.S.) takes care of that so that two trains cannot occupy the same space at the same time. The Bump A.S.S. system was my first exposure to 555 timing circuits and was where I devised the use of track gaps instead of reed switches so that any engine or rail car with metal wheels could be detected.

From there is was a natural jump to "relay logic circuits" to supplement the chip circuits.


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## toddalin (Jan 4, 2008)

I tried it out and fine tuned the new electronics over the weekend. This is very cool!  (Even Linda was impressed. )

If it takes a minute to make a loop, and I set it for (e.g.) 1 minute and 10 seconds, the train will make a loop and a half alternating between the station at Lizard Lane and the aerial tram.

Set it for 2 minutes 10 seconds, and the train do two loops before alternating, etc.


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