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[aprssig] Killer APRS use! ;)

Dave Baxter dave at emv.co.uk
Thu Mar 9 09:08:53 UTC 2006

The "Transponder" class of device is probably the better bet, than an
APRS beacon.

I used to have some designs for a single transistor VHF "Pinger" you
could detect with a normal broadcast RX.  It just "pinged" once a second
or so, very short pulse duration, more a ringing LC circuit kicked by a
unijunction I think.

Worked off a single dry cell, but no idea where the designs are now :(
I had one once that someone else built, was a bit of fun to throw it in
the garden over my shoulder, then DF it.

I seem to remember the basic circuit was from a medical journal of all
places, something to do with a body core temperature measurement task.
(The patient was suposed to ingest the thing!)  The C of the LC tank,
was the thermal sensor affecting the RF frequency of course.

Dave G0WBX.

> -----Original Message-----
> From: Alan WA4SCA [mailto:WA4SCA at AMSAT.ORG] 
> Sent: Wednesday, March 08, 2006 1:14 PM
> To: 'TAPR APRS Mailing List'
> Subject: [aprssig] Killer APRS use! ;)
> Hi,
> I came across the following application, which seems custom 
> made for APRS, on REC.RADIO.AMATEUR.EQUIPMENT.  Assuming 
> Shelly is not a Galapagos turtle, it will need a very small unit.  ;)
> Alan
> ==========================================================
> Every year, Shelly the tortoise gets lost or manages to 
> escape the garden.
> It can take days to find her.  I would like to build a 
> locating device so that I can track her down.
> The basic requirements are:
> a) that the 'transmitter (transponder?) on the tortoise is as 
> small as possible.
> b) that it can be made by an electronics numpty.  I  have 
> basic soldering skills, and can eventually work out a circuit diagram.
> Can anyone point me in the right direction?
> Floatything (an escapee from uk.rec.sailing) 
> ============================================================

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