Hi Azrael,

I know electrical contacts may be inexpensive, but kids spit and chew on
them just to make them corrode :) use plastic blocks that allow IR beams
through them (holes, IR panel, or IR clear plastic in the first place)

If that makes the cost too much, then since the blocks will presumable line
up well, embed a coil in the plastic (or up against a thin spot) and 'pulse'
the comms through.

Sounds like a good project.  Will you GPL the code ;-)


        cya,    Andrew...

PS:make the coils big enough and the 'equals' block can pulse power out to
the rest...   maybe...

> -----Original Message-----
> From: Azrael [SMTP:dunsms@RPI.EDU]
> Sent: Wednesday, October 13, 1999 12:53 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      What's in the train? The whole story.
>
>     Ok, since this post has gotten so many replies and gone off on more
> tangents than i thought possible I'll give the concept I'm working on.
> And
> maybe clear up some of the confusion that has arisin from my analogy.
>
>     The real project is designing "smart" building-blocks.  Around the
> size
> of Duplo blocks or other large "Lego" like blocks.  The goal is to create
> a
> set of blocks that can do math when connected in a correct order.  There
> will be number blocks, addition, subtraction, multiplication, and division
> blocks.  All of them are like the cars in the train.  The Equals block
> works
> like the engine to gather the order and type of block conected to it and
> computer the equation.  With such a small size, electrical contacts seem
> the
> most inexpensive way to go.  My buget is as low as I can make it.  The
> lower
> the better.  I went for a PIC that would just meet my needs (at $.90
> wholesale) and plastic and phone jack connectors for my contacts.  The
> block
> is being desiged by another group memeber but we are looking at cents
> each.
> The blocks cannot be plugged in backwards, they have a front and back.
>
> Dan Larson made a nice picture to illustrate this
>
>
> -----     -----     -----     -----     -----
> |   |---->|   |---->|   |---->|   |---->|   |
> | 7 |     | = |     | 5 |     | + |     | 2 |
> |   |<----|   |<----|   |<----|   |<----|   |
> -----     -----     -----     -----     -----
>
> Speed is pretty much not an issue, under a second is fine. In reality it
> should do it in a fraction of that.
>
> The Equals block is going to be an impresive bit of code, we have a lot
> more
> blocks than just numbers and simple math.  Since all the others are just
> slaves with an ID code, it all lies in there.
>
> If anyone has any input still,  I'm still open.  This is the second try at
> this project, now with a PIC chip and i hope i can acomplish my goal.
>
> -Stu