Azrael, Inductive power transfer can be very efficient (over 90%) and is quite easy to implement. At the power levels you are liable to need a U core about 10mm x 5mm legs would probably suffice if you can reduce the gap to a few mm (which you should be able to do). Signalling can be carried out over the same circuit with power off (alternate between power and data),. I am sending at 115 kbps over such an arrangement :-) although I do use different power and data cores. Power core needs to be resonant if large air gaps are used but is entirely workable non resonant with small air gaps. Capacitive coupling is another useable signalling technique. You may even be able to do power transfer capacitively if you have a high enough frequency - although this may raise some challenging EMC considerations. regards, Russell McMahon _____________________________ >From another world - www.easttimor.com What can one man* do? Help the hungry at no cost to yourself! at http://www.thehungersite.com/ (* - or woman, child or internet enabled intelligent entity :-)) -----Original Message----- From: McMeikan, Andrew To: PICLIST@MITVMA.MIT.EDU Date: Wednesday, 13 October 1999 18:35 Subject: Re: What's in the train? The whole story. PIC'a'Block >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 >