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David Prentice
03/18/12 04:53
Read: 468 times
Wormshill
England


 
#186767 - Sprung door with microswitch.
Responding to: Per Westermark's previous message
High tech solutions are not always appropriate.

A simple lightly sprung door can operate a mechanical microswitch.

1. easy to clean and maintain by unskilled operators.
2. can work in the dirty conditions.
3. microswitch is cheap and reliable.

Photocells, lasers, magnets, are more complex and susceptible to dirt, dust, iron particles ...

Some years ago, some friends from our computer club were drinking a beer at an outside cafe in Amsterdam (I think). As a tram approached, we speculated as to which track it would take.

We suggested computer controlled points, CCTV, hand of God, ...

In fact what happened was that the tram driver approached slowly. Examined the state of the points. Took an large crowbar from the tram. Set the points to his chosen route. Climbed back into the tram. Continued his journey.

David.

List of 23 messages in thread
TopicAuthorDate
counting objects inserted in tube      Damir Tadic      03/17/12 02:28      
   Cheaper?      Per Westermark      03/17/12 06:44      
      counting objects inserted in tube      Damir Tadic      03/17/12 11:31      
         What is the purpose of counting?      Andy Neil      03/17/12 11:42      
         Mirrors or multiple beams - still extremely cheap      Per Westermark      03/17/12 14:31      
         I guess there is a language problem here      Erik Malund      03/17/12 17:52      
            Specification Inadequate - Language Barrier?      Andy Neil      03/18/12 01:45      
               determine when receptacle at end of tube is full - Deja Vu?      Andy Neil      03/18/12 01:47      
            Language Barrier      Damir Tadic      03/18/12 13:54      
               "Simple and cheap" or dead reliable?        Kai Klaas      03/18/12 15:47      
               Not a solution?      Andy Neil      03/19/12 01:02      
               simple and cheap      Erik Malund      03/19/12 06:56      
   Do you know...      Kai Klaas      03/17/12 07:07      
   I hope      Erik Malund      03/17/12 08:45      
      eh?      Andy Neil      03/17/12 11:31      
         eh?      Erik Malund      03/17/12 17:42      
            Possible      Andy Neil      03/18/12 01:33      
               All This Pontificating....      Michael Karas      03/18/12 03:00      
                  Is a answer more important than the "correct" answer?      Per Westermark      03/18/12 04:17      
                     Sprung door with microswitch.      David Prentice      03/18/12 04:53      
                        Maybe but the bigger question was: what was tram destination      Per Westermark      03/18/12 06:17      
                        Already been suggested!      Andy Neil      03/18/12 08:10      
                  That information was not initially available      Andy Neil      03/18/12 08:07      

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