June 17, 2010
about 2 years ago
A few notes regarding what I discovered while playing with this part:
My original hook up had my 0-scope and notebook (the ID2 was plugged into the notebook for power) powered from a wall plug. The results were lousy and inconsistent. Ran everything off battery (no grounds) and, after tuning the antenna, wound up with better than 6" of repeatable range. Figured I had a ground-loop which would go away with only one device connected to AC but it didn’t work that way. With either the scope or the laptop connected to AC the range was shortened, sometimes to nothing. I need to re-test all that because maybe I did something stupid. It wouldn’t be the first time.
Building and tuning the antenna:
First off, get some construction paper and glue and build a good coil form so you have closely spaced turns. Five or six inch diameter is a good start. I got down to 4" before I ran out of wire and they all worked about the same. You want a groove to lay the wire in that keeps it closely wound so, whatever gauge wire you’re working with, figure about 70 turns and do the math to figure the width and depth of the groove. The turns don’t have to be wound perfectly, just fill up the groove evenly and keep the wires tight but not too tight (like a woman’s skirt, short enough to be interesting but long enough to cover the subject).
I wound up an antenna according to the data sheet recommendations, plus a couple turns. Hooked up my scope and unwound a couple turns until I got the max peak to peak voltage across the antenna, something like 180v. Unhooked the scope and the distance dropped a couple inches. Scratched my head and then thought “AH HA, probe capacitance!” plugged in a small capacitor parallel to the antenna coil and got the range back. I just ordered an LCR meter and think if I can tune the antenna exactly I might get more range. BUT, at this frequency we’re talking magnetic coupling, not RF, so any metal close by will likely de-tune everything and adversely effect range.
As for why the short range in the video, my guess is in the video everything was done on a metal desk. On the other hand, I just ordered an ID-20 to play with so, we’ll see.
For those looking for an antenna, I haven’t bought one of these but you could try: http://www.rfidshop.com/idi001-lf-antenna-for-id2-reader-19-p.asp
News - Eagle 6 Has Landed
about 3 years ago
A heads up regarding version 6 (including 6.1). When you upgrade at least sometimes it seems that restricted areas that are in libraries aren’t honored by the auto router, so it routs through them. The DRC will catch the errors and you can hand-rout to correct but…
Restricted areas that are designed on the board are honored.
No public wish lists :(
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