very small low power simple transmitter (ideally single chip)?

something like this?

martin

Yes exactly thanks!

One more Q..

Where might I source in a suitable small crystal for operation at somewhere between 144 and 146MHz?

ta

The best commercial tags still seem to use 2 or 3 transistors, with the smallest available SMD parts.

If you want a lot of choice, and various circuits to experiment with, I'd recommend you ask your local library to see if they can get the following:

"Scientific American" (Amateur Scientist columm, pgs 128-134) of March

"Mammal Review" pgs 118-141 Dec 1978. (This one is very good, and very practical)

"Biomedical Telemetry", MacKay 1968 (Wiley and Sons)

"Wildlife Radio Tagging, Equipment, Techniques and Analysis", Kenward, 1987

"A Manual for Wildlife Radio Tagging", Kenward, 2001.

The last two are pretty comprehensive, but include a lot on collecting and analysing data, probably not what you need.

Barry Lennox.

martin

Cat collar transmitters and receivers are commercially available.

But only absolute f*****ts buy them.

Go ahead - make my day.

........ Phil

...and I'm sure you have the ham radio license required for transmission in this band? And if you do, why are you asking the question in the first place?

Jim

I'd buy one of those $5, 418 Mhz transmitters. Then you need a PIC12F200 running in low power mode to send bursts of signal and extend the battery life.

Luhan

Ooops, that would be PIC10F200. 53 cents from Mouser.

Luhan

=============================== Why not bootleg something low power on the bottom end of the AM band and sniff it with a regular radio?

An antenna that would be at all effective on the AM band wouldn't fit on a cat. :-)

Radio Shack has key fob transmitters, but you'd have to hack a little micropower pulser, maybe a CMOS 555, or a 556 to do bursts.

A PIC, maybe, if he already has the development kit and knows how to program it.

Cheers! Rich

Hey, I believe I've been 'misquoted'!!!

Luhan

If it's under 100mW, is that not legal?

Mark

Is there an accepted band for use with animal tracking, rather than ther usual unlicenced bands?

martin

No. it has to be on specified band segments. Wade through CFR 47 for all the regulations for the US. Most other countries have similar regulations and laws.

No. For Part 15 rules (unlicensed operation), see

which says, in part....

Subpart C_Intentional Radiators

Sec. 15.209 Radiated emission limits; general requirements.

(a) Except as provided elsewhere in this subpart, the emissions from

an intentional radiator shall not exceed the field strength levels

specified in the following table:

------------------------------------------------------------------------

Measurement

Frequency (MHz) Field strength distance

(microvolts/meter) (meters)

------------------------------------------------------------------------

0.490-1.705...................... 24000/F(kHz) 30

30-88............................ 100 ** 3

216-960.......................... 200 ** 3

Above 960........................ 500 3

------------------------------------------------------------------------

According to the above, you are allowed 200 uV/m at 3 meters.

This is equivalent to 13 nanowatts of isotropically radiated power.

Cheers, John

I guess that makes my 500 milliwatt, 560,000 Gigahertz transmitter illegal!!!

(LED flashlight)

Luhan

It might be called out on this:

Or you could look at Radio Control eauipnent - they seem to be allowed a decent range, and AFAIK they don't need licenses. Have you ever been to a place where a bunch of folks are flying RC planes? They each have a streamer attached to their antenna, and the color of the streamer corresponds to which freq. they're on in the channel - it's sort of a gentleman's agreement that they won't step on each other's signals.

I have no idea what the common frequencies are[1] - a cat would look a little funny with a 6' whip antenna sticking out of its collar. ;-)

Good Luck! Rich [1] ISTR somewhere around 27 MHz and somewhere around 49 MHz, but quote me at your own risk! :-)

And even less, if your antenna has gain, right? Because it still has to be < 200 uV/m at 3 meters, looking right up the throat of the antenna, right?

So, what's the deal with those RF modems with thousands of meters' range? Are they, like, pre-licensed or something?

And will a signal that weak reach an RC airplane that's, say, 300m away?

Anyway, here's some frequencies:

Cheers! Rich