AVR-Chat

On Fri, 18 Feb 2005 19:26:17 -0000, Dave Mucha <dave_mucha@yahoo.com>  
wrote:

>
> IR would be fine, prefer to have extreemly close and not something
> that would work more than an inch apart.
> And, yes, each unit will have a battery.  Most likely a flat cell
> phone batt or similar
> Dave


I think coils would be better then.
My guts tell me it is easier to make it only work on close distances with  
coils. Light doesn't work well that way i fear, in air.

Can you guarantee some sort of alignment, like, imagining the pack of  
cards, that it would always lie flat and never stand on-edge? The RFID  
systems seems to have big problems with alignment, so if you were to use  
field strength as distance indicator you'd need to guarantee some  
alignment. I think the coupling between two flat coils could be used well,  
know the inductive-recharge contactless toothbrushes?

Sound might be another option, but can be disturbed by noise, depends on  
what you are doing.

Electric contacts seem only reasonable if you can ensure positioning etc.


ST