 | | A LEGO double-throw switch?
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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 (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) 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)
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| | Re: A LEGO double-throw switch?
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(...) hmm. At first, I would say "No". When you flip your switches at home, the switches could be in either of two states when the lights are "on". (one up, other down OR one down, other up) However, the LEGO polarity switches don't have to act like (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) 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)
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| | Re: A LEGO double-throw switch?
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(...) No, I think you should use one polarity switch, without handle to greatly reduce the friction needed to throw it. Putting the crate on the conveyor throws the switch, and when the crate gets to the other end it could push a lever, or better (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) 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)
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| | Re: A LEGO double-throw switch?
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(...) Since turning the 9V wire connectors 90 degrees reverse the polarity, can't you play with how the wires are connected to the switches to re-reverse the polarity on one wire? (...) -Kyle (19 years ago, 22-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) No, because it's only wrong half the time. HOWEVER, now that I think about it, you could mechanically connect two polarity switches together at the end with the motor. Then, instead of connecting one wire from each of the polarity switches to (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) I agree the simplest solution is to use a single switch with one linkage operated by the forklift to switch it on, and another linkage operated by the falling crate, that switches it back off, ready for the forklift. ROSCO (19 years ago, 22-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) 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)
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| | Re: A LEGO double-throw switch?
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In lugnet.robotics, Steve Hassenplug (& others) wrote: [snip a bunch of good ideas] Wow, ask a simple question... Currently I'm planning on using one switch that is normally off, and when the forklift delivers a crate it turns it "on-fwd". When the (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Ideally I'd like the package/crate itself to throw the switch, probably via pushing on an axle or liftarm extending from beneath. If friction is too low, I can always use a longer lever arm. Another alternative is to have the crate at the end (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Okay Brian - an electrical way...and remember, you didn't say "cheap" electrical way... So - we all marvel at the efficiency of Lego motors, right? You could put a motor at the tail end of the conveyor where the crate will hit it...it can be (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) 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)
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| | Re: A LEGO double-throw switch?
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(...) Only one problem...if you link the switches with an axel, they will be oriented such that they are always both on or both off. The on and off positions are 45 degrees out of phase, not 90... The concept is good (at least I think it will work (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) My bad! I've not used them much, but when I thought about how they were designed, I realized you are right. (...) This means gears, but gears mean play. One should be able to cancel the play by using a total of four gears. One gear for each (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Actually, I am not convinced it means gears. One of the switches could be mounted with a 45 degree tilt. This would remove the issue of play in the gears. You could also link the handle holes of the polarity switches with a solid piece (as (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Sure! Some assembly required! (URL) (...) Kev (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Linking via the handles would cause problems. First, there is a great deal of friction added to the system when an axle is in that hole. Second, I think the proposed method requires the switches to continue rotating the same direction. Steve (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) So - tilting one of the switches is probably the best approach. But I want to know where Brian Davis is. He started this blasted discussion :) And, Kevin, should I just send you my mailing address so you send me the parts? :) (BTW - it didn't (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) I was assuming that handles would not be used, because the switches would have to be "reset" if handles were used. Yes, the proposed solution would require one way rotation, but I assume that this would be simply done given the axle going (...) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) I'm pretty sure you can download the parts here: (URL) (19 years ago, 23-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Well, given that technic is quantized down to stud or half stud sizes, the solution may not be obvious. The easiest angles to create are due to 3-4-5 triangles. Most of the bent liftarms are bent based on those angles. The tri-blade liftarms (...) (19 years ago, 24-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Actually, I was working on this very thing (45 degree angles) for a new GBC module over the weekend. (you remember GBC, don't you? You know, the creature that wouldn't die :) - thanks Steve for such a wonderful way to waste all my free time :) (...) (19 years ago, 24-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) I'm here - just amazed at the chaos I kicked up :-). Incidently, I've grown to hate those tank tread belts (those, originally, were going to be the conveyor, but they are just too stiff). I've now got more ideas running around in my head as to (...) (19 years ago, 24-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) 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)
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| | Re: A LEGO double-throw switch?
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(...) Or, connect it to a technic turntable, so you can rotate it to any angle you want. ROSCO (19 years ago, 24-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) Which you can make rigid by merely using a rack or worm gear, and depending on space - some additional gears to displace the locking mechanism, however there may still be some play in that. OrionRobots (19 years ago, 25-Aug-05, to lugnet.robotics)
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| | FischerTechnik
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late last night I stumbled onto their website: (URL) vaguely remember playing with a set when I was maybe 10 yrs old. They seem to be trying to compete with Mindstorms lately, especially in the educational market. Does anyone have a set, and/or have (...) (19 years ago, 26-Aug-05, to lugnet.robotics)
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| | RE: FischerTechnik
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Have you seen the new Vex robotics stuff from Radio Shack? I think that is more of a competitor to mindstorms (several people on this list now have some experience with that). Larrry Whitman larry.whitman@wichita.edu (...) (19 years ago, 26-Aug-05, to lugnet.robotics)
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| | Re: FischerTechnik
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(...) Try here: (URL) (19 years ago, 27-Aug-05, to lugnet.robotics)
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| | Re: FischerTechnik
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(...) I don't see them as competitors. Here they are amicably side by side: (URL) LEGO, FT, and now Vex. They each have their own strengths and weaknesses. I use them all :) CS (19 years ago, 28-Aug-05, to lugnet.robotics, FTX)
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| | Re: A LEGO double-throw switch?
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"Steve Hassenplug" <Steve@TeamHassenplug.org> wrote in message news:24907.66.84.205...air.com... (...) I required something that will elimiate the need to worry about which way the motor is running, a one way foolproof motor drive mechanism might (...) (19 years ago, 29-Aug-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) So.... what was the final solution for this? Kev (19 years ago, 21-Sep-05, to lugnet.robotics)
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| | Re: A LEGO double-throw switch?
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(...) First, I learned a *lot*, so thank you all. As for which "solution" I ended up using, first disclaimer, I've not yet built a "crate conveyor". But some prototyping showed that the tank treads just have too much bending friction for what I (...) (19 years ago, 22-Sep-05, to lugnet.robotics)
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