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I teach photography/graphics at Beaufort High in Beaufort, South Carolina and we've done several high altitude balloon launches and have gotten some great photos. You can see them online at www.TheTalon.SmugMug.com/misc/space. In the past we've sent up a 9V piezo buzzer. I can't tell you how much it improves my life when we try to find the capsule.

Our next launch will involve a camcorder. I'd like to listen to it without hearing the buzzer. I wanted to use an arduino as a timer. It looks like I could use the sample blinking LED script to make it work... Just take out the line that turns it off and make it count to 7,200,000 (2hrs) before it starts.

Will I run into any problems with this?

73 and thanks in advance for the advice!  smiley
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Great pictures !

You can use the routine perfectly for a buzzer.

How did you track your Blimp by the way ?  Reading a 73 I'd guess a yagi  smiley-grin

I don't really know what the max. altitude for GPS modules is, wouldn't that be more interesting ?
Besides retrieving  your blimp you could use it to log all flightdata on an SD-card or Eeprom.


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"73" in amateur radio shorthand means "Best Wishes". And it’s a weather balloon…a 6ft wide, 1,200g weather balloon, not a blimp.  smiley-razz

There’s no real retrieving the balloon. When it reaches a certain altitude it bursts. Think of a sub…when it reaches a certain depth it gets crushed because of the pressure pushing in. When a balloon goes up, there is less pressure pushing in, allowing the balloon to expand. It will double in size every 18,000 feet. It can only stretch so far and at a certain altitude, a little over 100,000 ft, it bursts and the payload floats down via a parachute.

The upper limit of GPS devices depends on the GPS. The government limits GPS by speed and altitude. A GPS cannot work if it's moving faster than 999 mph AND is over 60,000 ft. Basically, they don't want anyone using a GPS to guide a missile. To comply most manufactures cap their GPS's at 60,000 ft.

I've got two devices for tracking. The first is a SPOT satellite transmitter. It gets a position from a GPS then transmits it to satellite every 10 minutes. You can read the location from a website. The site can be public or it can be protected with a password. Unfortunately the SPOT will not tell altitude. It's also only rated to 30,000 ft. On the upside, it will give you position on the ground.

The second device is an amateur radio (ham) transmitter. Every 30 seconds it sends a position report. It tells me longitude, latitude, altitude, speed and direction. I can download the flight data from http://aprs.fi after the flight. The GPS attached to the ham transmitter (a Garmin 18x) will work above 60,000 feet.

I use the buzzer because even though you get VERY accurate position reports, it’s hard to find a capsule that’s sometimes 50 feet up a tree. Not with the buzzer. You can hear it 500 yards away and close in easily. The only problem is, this time I’m also sending up a HD video camera and I don’t want to hear the buzzer the whole time.

I just ordered the starter kit from adafruit. I think the arduino combined with a ham radio license will definitely put me near the top of the nerd scale. A slide rule can’t be far off.  smiley-wink
« Last Edit: March 10, 2011, 09:36:54 pm by tstowe » Logged

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Now, since my buzzer is rated for 9V, I won’t need to use a resistor…right? Just set it up like this but with a jumper where the resistor is located? Or can I just plug the buzzer in directly to the arduino?


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I see you guys aren't a real talkative bunch.    smiley-confuse
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nr Bundaberg, Australia
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If it's rated at 9v how well does it work at 5?

What's your VIN?

I think you will need to drive the buzzer from VIN with a transistor.

_____
Rob
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Sorry for not responding, It's been a bit like a circus over here, no balloons unfortunately.

To be honest, I don't know much about buzzers. I would think one could attach a buzzer the way you like, but I'd check how much milli-Amperes will flow by hooking it directly to 5V.

More as 40mA on a pin might damage the controller. In that case you'll need a resistor (making the buzzer less loud) or transistor capable of driving higher currents.

100.000 feet sounds great, living close to the beach I met some guys taking KAP-pictures (Kite aerial Photography) last year. They didn't need a buzzer, but... didn't get much higher as 1200-1400 feet. (still very impressive and great pictures)

Thanks for explaining how you do track the balloon, it's interesting to read. A few "centuries" ago I've been sysop of a packet-radio-BBS on CB for a few years, every two weeks we had an ARDF-contest with Hams, so my first guesses were Yagi, Parabolic antenna or GPS. But... Internet became available, nr. of users dropped rapidly and I took a left turn where I could have turned right.

73+55  smiley,

Bart.


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A 9v buzzer probably will run at 5v but not very loudly. Plug it in a see.

40mA is the absolute max and should not be used, 20 is safer.

If you use a transistor from 5v you will only get ~4.3v across the buzzer, so that's even worse.

If you are happy with the 5v sound you could use a FET, OR if the buzzer draws < say ~25mA drive it directly.

As I said, I think you will need to drive the buzzer from VIN with a transistor.

EDIT: The ABI-001 peizo buzzer works from 2-12v and draws 7mA. I plan to use one on a board I'm currently designing and drive it direct, but that's just for a keypad beep, I don't know how loud it will be.

_____
Rob
« Last Edit: March 13, 2011, 07:48:37 pm by Graynomad » Logged

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The buzzer is rated from 7 to 14V…Ok, remember, I’m new to this…so I’d go from the VIN power pin to a transistor, then to the buzzer?
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Normally you do this

VIN---BUZZER---TRANSISTOR----GND

Have a look in the playground for motor or solenoid driving, it's the same principle.

______
Rob
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Graynomad...thanks for the info. I'll look into that.

KE7GKP...That’s a little more than I want to get into (right now anyway). But it’s not that much of a guess. If I put the right amount of helium in the balloon for the weight of the payload and I have the right size parachute, the duration of the flight is fairly predictable. I run predictions (found at http://nearspaceventures.com/w3Baltrak/readyget.pl) that will give me a flight time too.

Now as far as varying the sound, it’s pretty easy to find at a constant buzz. The GPS will get me to within a few hundred feet and it’s so loud, it’s kinda hard to miss at that range. smiley
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I tell you what I wouldn't mind having the arduino do...

I don't use a cutdown device but I wouldn't mind using an arduion to activate one. Basically, what it does is if for some reason something goes wrong...it's going in a direction you didn't expect...it isn't rising fast enough (meaning it would come down somewhere you didn't want)...etc, it would cut the line between the parachute and the balloon. Ideally, it would be controlled by a radio signal on the ground but I've seen them work of off a timer too. Most of them heat up a section of nichrome wire that would cut through the line once activated. smiley
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I'd suggest adding a relay-circuit to heat up nichrome wire.

It could also be done by driving an heavy transistor, finding the right one may take some time and
you probably want to be sure that it works/won't fry while flying.

I'm more interested in digital as power related stuff though, perhaps it could... be done just as well with the right transistor.

http://arduino.cc/playground/uploads/Main/relays.pdf

Without relay you could use a similar circuit and connect the nichrome wire where the coil of the relay is located.


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