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

M

#### megoodsen

Jan 1, 1970
0
I'd like to build a very small, low power RF transmitter circuit that
is small and light enough (and cheap enough not to worry about) to be
attached to a cats collar.
I just want it to transmit either a constant or pulsed carrier (pulsed
prob best for battery life) of a known frequency, that I can monitor
with a receiver and DF antenna.

There must be single chip transmitters about these days?

Anyone suggest suitable circuit?

M

#### martin griffith

Jan 1, 1970
0
I'd like to build a very small, low power RF transmitter circuit that
is small and light enough (and cheap enough not to worry about) to be
attached to a cats collar.
I just want it to transmit either a constant or pulsed carrier (pulsed
prob best for battery life) of a known frequency, that I can monitor
with a receiver and DF antenna.

There must be single chip transmitters about these days?

Anyone suggest suitable circuit?
something like this?

http://www.jbgizmo.com/page4.html

martin

M

#### megoodsen

Jan 1, 1970
0
One more Q..

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

ta

B

#### Barry Lennox

Jan 1, 1970
0
I'd like to build a very small, low power RF transmitter circuit that
is small and light enough (and cheap enough not to worry about) to be
attached to a cats collar.
I just want it to transmit either a constant or pulsed carrier (pulsed
prob best for battery life) of a known frequency, that I can monitor
with a receiver and DF antenna.

There must be single chip transmitters about these days?

Anyone suggest suitable circuit?

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
1968 . You can get all the Amateur Scientist articles on 2 x CDs for
about $30 now. "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. P #### Phil Allison Jan 1, 1970 0 ** Groper alert ! Yes exactly thanks! ** Lotsa luck - that schem is fake. Cat collar transmitters and receivers are commercially available. But only absolute fuckwits buy them. Go ahead - make my day. ......... Phil R #### RST Engineering $$jw$$ Jan 1, 1970 0 ....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 L #### Luhan Jan 1, 1970 0 megoodsen said: I'd like to build a very small, low power RF transmitter circuit that is small and light enough (and cheap enough not to worry about) to be attached to a cats collar. I just want it to transmit either a constant or pulsed carrier (pulsed prob best for battery life) of a known frequency, that I can monitor with a receiver and DF antenna. There must be single chip transmitters about these days? Anyone suggest suitable circuit? 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

L

#### Luhan

Jan 1, 1970
0
Luhan said:
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

B

#### BobG

Jan 1, 1970
0
===============================
Why not bootleg something low power on the bottom end of the AM band
and sniff it with a regular radio?

R

#### Rich Grise

Jan 1, 1970
0
===============================
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

L

#### Luhan

Jan 1, 1970
0
BobG said:
===============================
Why not bootleg something low power on the bottom end of the AM band
and sniff it with a regular radio?

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

Luhan

M

#### Mark

Jan 1, 1970
0
RST said:
...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

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

Mark

M

#### martin griffith

Jan 1, 1970
0
...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
Is there an accepted band for use with animal tracking, rather than
ther usual unlicenced bands?

martin

M

#### Michael A. Terrell

Jan 1, 1970
0
Mark said:
If it's under 100mW, is that not legal?

Mark

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.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

J

#### John - KD5YI

Jan 1, 1970
0
Mark said:
If it's under 100mW, is that not legal?

Mark

No. For Part 15 rules (unlicensed operation), see
http://www.access.gpo.gov/nara/cfr/waisidx_05/47cfr15_05.html

which says, in part....

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)

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

0.009-0.490...................... 2400/F(kHz) 300

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

1.705-30.0....................... 30 30

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

88-216........................... 150 ** 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

L

#### Luhan

Jan 1, 1970
0
John said:
No. For Part 15 rules (unlicensed operation), see
http://www.access.gpo.gov/nara/cfr/waisidx_05/47cfr15_05.html

which says, in part....

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)

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

0.009-0.490...................... 2400/F(kHz) 300

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

1.705-30.0....................... 30 30

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

88-216........................... 150 ** 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

R

#### Rich Grise

Jan 1, 1970
0
On Fri, 18 Aug 2006 10:24:01 -0700, in sci.electronics.design "RST

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

It might be called out on this:
http://www.ntia.doc.gov/osmhome/allochrt.pdf#search="allochrt.pdf"

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

R

#### Rich Grise

Jan 1, 1970
0
No. For Part 15 rules (unlicensed operation), see
http://www.access.gpo.gov/nara/cfr/waisidx_05/47cfr15_05.html

which says, in part....

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)

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

0.009-0.490...................... 2400/F(kHz) 300

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

1.705-30.0....................... 30 30

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

88-216........................... 150 ** 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.

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:
http://www.modelaircraft.org/Comp/frequency.htm

Cheers!
Rich

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