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Author Topic: Locating tiny models in long grass  (Read 1198 times)
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Tapio Linkosalo
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« on: July 20, 2010, 07:44:06 AM »

After a couple of weeks of paddling around the lake Saimaa, I return to my experiences in the Swedish Glider Cup. Had great fun tinkering my two "Rakt Upp" models, even though looking backwards I was just like Mick Page describes in his Aeromodeller article: had trimmed the models in nice and calm, came around with high spirits, and then realized that on a real contest day there may be turbulence around!

But my point is, actually, that I had real hard times finding the models after flights. So I wonder if there would be any technical means to help finding the models? The smallest radio beacons are several grams, so that it too much? How about some beepers? Especially if the model would sport a digital timer, then the tiny lipo battery could be used also to power the beeper, so a tiny piezo might not add more weight than half a gram maybe? Or maybe add a LED and wait for the evening to locate the model :-)
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Tmat
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« Reply #1 on: July 20, 2010, 08:12:26 AM »

Yes, finding the little critters in long grass is a challenge Tapio. Bright fluorescent colors help for the wing tips and also the stab and fin tips. A beacon might help, but it's almost not worth the risk to a good beacon?

A beeper might be a good idea if the weight isn't too high. A 17" to 18" span clg can still be useful for contests at an all up weight of 30 grams (although 24 to 27 gm is perhaps more ideal) so you can have some weight to play with. I've added a 3.5 gram altimeter to a 26 gram model (18" span) and saw very little change in the altitude and the glide was a bit more stable in the turbulence. That's about the weight of a beacon so it's do-able.

LED's might be even more useful in flight to allow the timekeppers to keep sight of small models!

Keep paddling, you're getting good ideas!

Tony
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ArneH
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« Reply #2 on: July 23, 2010, 06:08:33 PM »

I have played with the idea of using a key finder to find lost objects. It might be to big, but maybe it's possible to only use the electronic in it.

You can read more here:

 http://www.keyringer.com/

Smart little thing I think I need for everyday use. Roll Eyes
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Re: Locating tiny models in long grass
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Tapio Linkosalo
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« Reply #3 on: July 28, 2010, 09:04:44 AM »

Keep paddling, you're getting good ideas!

Wish I could, as the heat wave still is parked over Finland, today 33C, while temperatures over 25C are typically unusual in Finland. This is the warmest summer in the past 100 years! It seems that the hot air is flowing in from southern Asia, while the winds usually blow from Central Europe.

Anyway. Have been browsing HobbyKing web pages. They have a new, interesting servo that weights only 1.7 grams. Add to that a 50mAh lipo cell (1,8) and a PIC microchip (neglectable weight), you might get a (multifunction) timer with beeper to 4 grams. Gotta order some parts a give it a go!
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Tmat
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« Reply #4 on: July 28, 2010, 11:32:38 AM »

You can get some very small 20 mah Lipos for about 5 dollars. I believe that they weigh 0.8 grams. Should be enough juice.

Tony
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Tapio Linkosalo
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« Reply #5 on: July 28, 2010, 04:37:59 PM »

But maybe not enough juice for the beeper?
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Tmat
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« Reply #6 on: July 28, 2010, 06:11:59 PM »

Ahh, the beeper!

What beeper did you have in mind Tapio?

Tony
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danberry
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« Reply #7 on: July 29, 2010, 12:16:28 AM »

Get a greeting card that plays a tune when opened. Strip the card and use the device.
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Tapio Linkosalo
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« Reply #8 on: July 29, 2010, 12:34:38 AM »

Yep, something like that. The greeting cards use simple piezo-electric "disks" as sound devices, the electronics in the "card" send square waves at different frequencies to the disk to play different tunes. If we have the (PIC) microcontroller onboard, it can do the frequency part. I have not yet digged into actual parts, but small beepers should weight less than half a gram.

Thinking back while I write this, the RAM3 logger also has quite a loud beeper. Have to see, what component it uses. I'll be back.

Edit: found it: Cui Inc. CCV-084B16. Magnetic buzzer, not piezo. Requires square wave to run. Loud! (When I download my logger data to PC, I usually cover the holes of the logger with fingers to get rid of the annoying modem noise the unit emits, as the beeper shares a output pin with the serial send...); min 85 /typ. 90) dBA at 10cm. Weight 0.46 grams. Available for instance at Digikey: http://parts.digikey.com/1/parts/66-buzzer-audio-magnetic-3-6vdc-smd-ccv-084b16.html
« Last Edit: July 29, 2010, 02:18:20 AM by Tapio Linkosalo » Logged
Maxout
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« Reply #9 on: July 29, 2010, 12:11:37 PM »

Tapio,

 Hmm... I like the looks of that unit. It says 3.6 VDC, so does that mean we just supply it that power and it gives us noise, or is there a controller input required as well? I'm really interested in getting some of these for my scale jobs, as the inability to get an exact location on a model cost me a placing at the nationals.
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Tmat
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« Reply #10 on: July 29, 2010, 12:39:06 PM »

Very interesting beeper Tapio!

I just found the spec sheet: http://www.cui.com/getPDF.aspx?filename=CCV-084B16.pdf

You need to give it a square wave at a certain frequency Joshua, so you can't just connect it to a battery.

The current draw seems high though Tapio (110 mah). A 50 mah battery would be dead in less than 1/2 hour. Perhaps it should be pulsed to give short "tweets"? And of course only after DT. Certainly a good little device for catapult gliders or small rubber models in tall grass or crops.

I also like the idea of the key finder type of device. Then the battery is only used when you push the button and only when you are close to the model.

Tony
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Tapio Linkosalo
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« Reply #11 on: July 29, 2010, 12:49:11 PM »

You need to give it a square wave at a certain frequency Joshua, so you can't just connect it to a battery.

Quite right.


The current draw seems high though Tapio (110 mah). A 50 mah battery would be dead in less than 1/2 hour. Perhaps it should be pulsed to give short "tweets"? And of course only after DT.

Yup, the high current (I guess it is the same for all critters making 90dB noise... current is energy is strong sound) is the reason I think a larger battery is needed, it all boils down to the C-rate of discharge. And yes, shorter beeps should be OK. As a matter of fact, beep-beep-beep -sound is easier to recognize than constant buzzing, that can merge into the general noise background, or the tinnitus in your ears.
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szastoupil
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« Reply #12 on: August 04, 2010, 03:10:34 PM »

Something like this may be something to consider. Yet another variant of a keyfinder. They are saying 5 grams for the tag, but not sure if that is with or without battery. Put the tag on a diet by removing the case and LED.

http://www.loc8tor.com/Store/product/Loc8tor-Lite,154,110.aspx

Scott
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Tmat
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« Reply #13 on: August 13, 2010, 01:13:51 PM »

Scott, that is an even more interesting locator! I think you are right. You should be able to ditch the plastic case and might even be able to replace the two batteries with a small Lipo that should be much lighter (20 to 50 mah).

A bit pricey as a system, but if it allowed me to find a small model in a crop or long grass it would be worth it.

Tony
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