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Subject: 
A LEGO double-throw switch?
Newsgroups: 
lugnet.robotics
Date: 
Mon, 22 Aug 2005 19:05:37 GMT
Viewed: 
931 times
  
   So I've got an application where a forklift loads a crate onto a conveyor
belt. I could then start the conveyor belt up by having the forklift throw a
polarity switch. What I would *like* is that when the crate gets to the other
end, it somehow stops the conveyor motor again, (here's the tricky part),
leaving the system in a state where the next forklift delivery can re-trigger
the whole system from the "front end", as it were.
   Oh, did I mention I wanted to do this with just polarity switches, no RCX or
other "intelligent" systems in the loop?
   The picture I've got in my mind is something like a light with two wall
switches - change the state of either switch, it changes the state of the light.
I'm thinking I can do it with a looong string from the terminal end back to a
polarity switch at the head of the line, but it seems... clunky. Is there any
electrical solution? Can I reproduce my household wiring in LEGO (I promise I'll
keep the voltage... a *little* lower)?

--
Brian Davis



Message has 7 Replies:
  Re: A LEGO double-throw switch?
 
(...) Yes I'm sorry for not drawing it.. but here goes Imagine you have a cable with ground and a cable with 9V You need two single pole, double throw switches (I don't know what kind lego switches are) For both switches, connect one throw to 9V and (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
  Re: A LEGO double-throw switch?
 
(...) Hi Brian, How will the package arriving at the other end "throw a switch?". Is there enough friction between the package and the belt? Will there be a mechanism in the belt itself to "go halfway and stop"? If you only used one polarity switch, (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
  Re: A LEGO double-throw switch?
 
(...) Ok, Here's a partial solution (assuming you don't want to mechanically link the ends together). Given: Polarity Switch 1 - rotated forward by Forklift Polarity Switch 2 - rotated forward by crate when it arrives at the end Motor - located by (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
  Re: A LEGO double-throw switch?
 
(...) Brian - Since I am a spark head...let me just say....this would be interesting. Presumably, you are moving a polarity switch from one "on" position to the next when you hit it...because going to an "off" position would disable the system. (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
  Re: A LEGO double-throw switch?
 
(...) We can use two polarity reversors to create a three way switch. Set two polarity reversors side by side, linked by an axle. Set it up so that when one reversor is on (no matter the polarity), the other is off. If we drive 9V into both (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
  Re: A LEGO double-throw switch?
 
(...) The following design will turn a polarity switch into a two-way splitter. (URL) That is, the switch controls whether the input will go to the left output or the right. Use two of these, one at each ends of the conveyor belt, to make a (...) (19 years ago, 24-Aug-05, to lugnet.robotics)
  Re: A LEGO double-throw switch?
 
(...) So.... what was the final solution for this? Kev (19 years ago, 21-Sep-05, to lugnet.robotics)

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