Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!amdcad!neptune!zahid
From: zahid@neptune.AMD.COM (Zahid Ahsanullah)
Newsgroups: sci.electronics
Subject: Re: Extremely small transmitter - help!
Message-ID: <522@neptune.AMD.COM>
Date: 9 Feb 88 00:33:07 GMT
References: <1434@obelix.liu.se>
Reply-To: zahid@neptune.AMD.COM (Zahid Ahsanullah)
Distribution: na
Organization: Advanced Micro Devices, Inc., Austin, Texas
Lines: 34

In article <1434@obelix.liu.se> per-el@obelix.liu.se (Per Elmdahl) writes:
>
>Hello, world!\n
>
>A friend of mine wanted some advice, so I decided to ask the Net!
>
>My friend is attending a course where he is going to make an
>electronic construction. His project consists of constructing 
>and building a tiny transmitter for measuring the temperature
>in the stomach of a snake! (Can you believe it?). Now he is 
>-- 
> / Per Elmdahl  SM5OCI  ( enea!liuida!obelix!per-el , per-el@obelix.liu.se )

I don't know if this is going to be tiny enough but if he builds a bridge
circuit with one of the arms of the bridge being a 1mm dia glass thermistor
caliberated over the desired temperature range. He can then run the output 
through a voltage to frequency convertor which feeds a single transister (pnp) 
rf oscillator using the following specs on the tank circuit.

	1000 Pf capitor in parallel with a coil made up of
	30 turns of 25 SWG wire center tapped at 15 turns.

This would give him a short range transmitter of maybe 100 ft if powered
with 4.5 volts, transmitting at top band range. The transister used can be
any low power oscillator (AF117 is a good one). The receiver should be capable
of converting frequency to temperature.

Circuits similar to the one I've described can be found in any electronics
circuits manual type books. Have him look under microphone transmitters.

Hope this helps him somewhat.
			
					regards
					 Zahid