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Subject: 
Re: So THAT's what it does...
Newsgroups: 
lugnet.trains
Date: 
Mon, 8 May 2006 17:28:01 GMT
Viewed: 
3551 times
  
In lugnet.trains, Jason J. Railton wrote:
   Final post then - Tim jumped the gun a bit with sidebarring me, as this is the final image:

snipped

  
What I’d love to be able to do is detect the current flow of a running motor in the supply wire. Then I could build a simple sound-activated reverser, that holds off until the train has reached the other end. But, I can’t find a suitable component to sense the current, that wouldn’t be fried by a transformer on full power.

This is a nice project for Mindstorms, but I think my solution is a lot cheaper to implement. I’m currently working on a modification to turn two switches for shuttling two trains.

Jason R

Jason, nice work.

I had been toying with the idea of using a RCX or a timer circuit for the same thing. You can even put a few extra back to back diode isolated tracks before the end sections to simulate acceleration and deceleration. And get stopped train detection. http://home.cogeco.ca/~rpaisley4/AutoRevCheap.html



A comonly used “sensor” for track occupancy detection is a pair of power diodes back to back. Put these in series with the track power connection to an isolated section of track. When a train moves onto the block, it closes the circuit, and you get 0.7v across the diodes. The polarity tells you the direction the the motor is traveling.
http://home.cogeco.ca/~rpaisley4/BODGP.html http://home.cogeco.ca/~rpaisley4/CircuitIndex.html#24

Mat



Message has 1 Reply:
  Re: So THAT's what it does...
 
(...) Ah, now that's a good idea. A couple of diodes in series could cope with the power, and provide a consistent and measurable cue that current is flowing. I could use that to turn off a sound sensor whilst the train is moving, then enable it (...) (19 years ago, 9-May-06, to lugnet.trains, FTX)

Message is in Reply To:
  So THAT's what it does...
 
Final post then - Tim jumped the gun a bit with sidebarring me, as this is the final image: (URL) for gallery>> Click for gallery. (URL) I've included pictures of my modified track: (2 URLs) I've also included a few diagrams of what the diode does: (...) (19 years ago, 8-May-06, to lugnet.trains, FTX)  

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