Alt-BEAM Archive
Message #08428
To: beam@sgiblab.sgi.com, beamboter@hotmail.com
From: "Ben Hitchcock" beh01@uow.edu.au
Date: Sun, 19 Dec 1999 15:01:08 +1100
Subject: [alt-beam] Re: OT:Car Remotes...Clarification
>From: "Jim Cook"
>I messed up, I wasen't clear, I think.
>
>I am refering to the little key chain Car ALARM remotes, which lock and
>unlock the doors, and set the alarm.
Ahhhh.
Well in that case, it's usually around 300 MHz. The higher frequency is so
you can use a smaller transmitting aerial.
>Any one know about those?
>
>As for the Crystal it has 315M6, and 591. Any guess which is the freq.?
I would guess that your doodad transmits at 315 MHz. If the silver thing is
sort of flat and disc shaped like a little button, check underneath the
board to see how many legs it has. If it has three then it is almost
certainly a SAW (Surface Acoustic Wave) resonator. I have no idea how these
are different to a normal crystal resonator but apparently they are.
I just completed a project for university using one of these devices. If
anyone's interested, you can find schematics and pictures at:
http://www.wollongong.apana.org.au/~ben/elec250/
There's a pretty poor excuse for an index there but that's all I did in the
time I had available.
There's the product webpage as well, but it's not that interesting - mostly
just pages trying to entice you to buy the product (It's not really for sale
but we have to pretend for the uni's sake).
It's at
http://www.wollongong.apana.org.au/~ben/elec250web/
Ben Hitchcock
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