[Oracle]

Hi,

I am interested in adding a tracking transmitter. I was thinking of scratch building it from circuit schematics I found on the internet. I like to scratch build circuits as a hobby too. I was think of using the transmitter M15m (147.460 Mhz) from www.jbgizmo.com/page32 and one of the receivers from www.open-circuit.co.uk

Anyway, before diving into this project, I would like some help. I am not licenced as a HAM or anything. But if forced to, then I will be. I am planning to only use it as a tracking tx for my plane in case its lost, nothing else.

From what I understand, this frequency would be for licenced users? But are there any frequencies unlicenced people can use?? most in particularly like in the 150mhz, or 220mhz?

Or limited power output in order to be allowed? The transmitter I listed used intervals of 1 second, in CW. It used a single cell "button cell" those watch type batteries, so the power output is very small. It does say the range is about 400 yrds.

I did look at some "commercial" tracking transmitters for r/c and some of them are offered for the unlicenced user in American and UK. I am uncertain what the regulations are for CANADA.

Can someone clearify please.
Thanks.

[Shawn68z]

You might want to look into Lynx Technologies

http://www.linxtechnologies.com/

they make RF links (TX'er and RX'er). Most of the frequencies they use are in the unlicensed 2.4Ghz range. If you buy there modules, they are already passed by the FCC, so they shouldn't be a problem.

Instead of a RF signal, what about a audiable alarm (like those electronic rape buzzers) you could set it up to an accelerometer to only go off after a crash (say 35 G's?). Plane hits the ground and the buzzer sounds for awhile. Pretty loud, and you wouldn't have a problem with the RF TX'er interfering with the planes RX'er.

Heck, if you are going to have a transmitter on your plane, you should add GPS to the plane too! futurelec.com sells GPS IC chips for $40.

Shawn.

[Oracle]

Thanks for the quick reply.

I rather not buy completed units since they are priced expensive. There is an electronics components company near me with low prices. Judging from the cicruit schematic, I can make a transmitter for about $5 - 10 Cdn. Also, I like to solder...hehe.

I looked at the "sound" alarm types, but that does not interest me, heck, it would be more fun pulling out the antenna and headphones, and trying to find the model.

Any other help with concerns of the frequency and power output regulations for non-licenced user topic, would be greatly appreciated.

Thanks.

[Dave Holmes]

A lost model alarm is the simplest way to go. It plugs into an unused socket on your Rx, or into an occupied one via a Y cable. When it loses Tx signal (ie you turn it off) it detects the absence of control pulses and starts to sound. I can hear mine from over 100 feet. (variable depending on wind direction and ambient noise)

Also serves to warn you your receiver is still on if you turn off your Tx after a flight, and if you turn the Rx on first and you DON'T hear a tone, you want to check for someone with a Tx on your channel.

Here are three circuits on line. Neither is the one I used, but I am having difficulty locating the site where I got my circuit.

http://www.bumpygreen.co.uk/Articles...modelalarm.php

http://www.uoguelph.ca/~antoon/gadgets/locator.htm

http://homepages.tesco.net/ada.tippett/Radio4.htm#G

If you are not into fine soldering, you can buy ready built ones for about 20 bucks. One important point, most of the sounders need to be vented to the open air, not closed up in the fusilage. That will cut the volume hugely. I know a piece of tissue paper over the vent hole on my sounder cuts the volume about 50%, or about 3db, so I cut a hole in the bottom of the fuse and glued it in with goop.

My experience has been that you can walk right past a plane in tall grass or brush, and be within 2 meters or less and miss it. But with one of these babies on board if you are in the ball park, you are good, unless it is a really bad crash and the battery gets disconnected. (Yep, that's happened too!)

To avoid that you could power the alarm from its own pack, taping it to the alarm and run two wires, negative (common) and signal across to the Rx, so if it gets disconnected it will sound as well.[/url]

[Dave Holmes]

I found a copy of the circuit I use. the most expensive part is the sounder from "The Source" (aka Radio Shack)

Substitute a 2N3904 for the BC237 transistor and a pair of 2N3906s for the BC327s. Wire it up on a bit of veroboard and it's less than 1 inch square.

[Shawn68z]

Thanks Dave!

Thats definately a cheap piece of insurance when hunting for your plane!


Shawn.

[Oracle]

Nice circuits for the sound alerms.

I am gonna stick with radio ones. A person had mentioned to me that maybe 150-160 Mhz and 217 Mhz could be used by non-HAM licenced people, but with limitations in power output, but this was uncertain. Would be good to know if someone knows this better???

Anyway, in the meantime, I am thinking of maybe going for the HAM licence and avoid the headaches. That morse code looks interesting too, although it is not required for the exam.

[Ken Currell]

Hi

Why don't you check with industry Canada about the use of those frequencies.

That would be your best bet. They should know the answers to your questions.

Cheers

[Oracle]

Hmm, that didnt occur to me...LOL. I shall.

I did call up Radio Amateurs of Canada association and they did not know for certain either. But, definitely industry Canada must know this.

Thanks.

[Dave Holmes]

As long as you're under 100 milliwatts to the output stage of a transmitter, you're ok. (That's input power to the final amplifier, not power to the antenna)

There are several circuits on Tony Van Roon's web site at the U of Guelph that may do the job, most of which broadcast in the lower end of the FM radio band, so a small hand held transistor radio with a directional antenna would work as a DF.

The first link is to a "tracking transmitter" circuit, but it has no description detailing operating frequency, etc.

The second actually looks the most promising, as it provides and audible signal in a receiver.

The remaining four are FM voice transmitters, so you would have to add an audio oscillator in place of the mic to modulate the carrier.

http://www.uoguelph.ca/~antoon/circ/txtrack.htm

http://www.uoguelph.ca/~antoon/circ/tx15trak.htm

http://www.uoguelph.ca/~antoon/circ/fmt1.htm

http://www.uoguelph.ca/~antoon/circ/fmt2.htm

http://www.uoguelph.ca/~antoon/circ/fmt3.htm

http://www.uoguelph.ca/~antoon/circ/fmt4.html

Also, he has a whole page of links to RC related electronic projects, most on his own site, some not.
http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm

Plus two more:

http://www.jbgizmo.com/page21.html

http://www.jbgizmo.com/page22.html