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Old Jan 30, 2011, 03:42 AM
PLD
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Altimeter switch / LED-Alert for being 'too high'

With R/C activities coming under a lot more scrutiny these days, we have to do our best to keep within the rules that are laid out to us for the fields we have.

One of the most commonly violated rules seem to be the height/altitude ceiling (300~400' AGL).

After being approached a few times by various people and finally last month, I decided to see what I could do any put together an independent altitude alert system.

The operation is very simple - there's a single button the board which you press X times for X00' altitude (eg, 4 times for 400'). I might change this to 50' increments but for now it'll be 100'. The altitude is saved until you change it again, a single LED on the board will blink out the number to you as a reminder. The board will automatically reset the ground-level to what ever height the plane is set at at the time of being turned on.

The precision of the unit will be about 10~20', so if you set it to 400' AGL you'll have the alarm trigger at 400' +/-20'. I could have built it with a lot more precision but considering that with normal flying we rarely can hold more than 10' altitude precision for long.

On the BACK of the board will rest a nice bright 1W LED, I've not yet worked out what colour to use for optimal visibility but I'm starting with Amber with ~35 lumens output (I can get green at 65 lumens but it's a lot more expensive). Now, as we all have different wants/needs I'll ALSO be producing a version of the board without the LED but with a 2 pin header to let you plug in your own choice of LED/alarm (up to 1A current).

The board is only 1x1", it'll have 4 mounting holes. The LED on the back (for the ones built with that) is only about 8mm diameter and has a beam about 120~140 degrees wide.

The whole system can be powered by a 2S lipo or LiFe or a 5~6 cell Ni pack. I strongly recommend not putting this on your receiver power bus because of the load it'll induce when firing the LED off for the alert.

The cost will be somewhere between $50 and $60 AUD, depends on the numbers I can get sold as the pressure sensor costs quite a lot of money and only when I get to units of 100 orders does it drop down to a sane level.

Paul.
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Old Jan 30, 2011, 03:53 AM
PLD
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I should point out that the LED will be 'strobed' to provide maximum visual impact.
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Old Jan 30, 2011, 04:26 AM
Chillaxin dude!
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interesting concept Paul... watching this one.
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Old Jan 30, 2011, 04:40 AM
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I'd take one of them.

I'm happy to pre order / pre pay if you're sure enough of your ~$60 price point.

A suggestion, in case you're interested, I'd like this to be able to be plugged into my throttle channel and have the esc pluged into it so it can kill the motor above the pre-set altitude.

big
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Old Jan 30, 2011, 04:41 AM
PLD
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It's obviously more of a safety/compliance device than anything really "bling" worthy


The boards have already been put into production but with the Chinese new year I'm not sure as yet when they'll arrive here.

Testing is going to be interesting, I dare say quite a bit of driving up and down the local hills

Paul.
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Old Jan 30, 2011, 04:46 AM
PLD
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Big,

Right now, to provide a throttle-inhibit facility I'd have to change the controller chip or lose the LED-beacon functionality. Actually, the more I think of it the more likely it'd be a separate, slightly more advanced product.

Paul.
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Old Feb 04, 2011, 12:17 AM
PLD
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Hey there folks, just back in finally after being 'lost' for a week due to TWO cyclones hitting the coast during the week.

Anyhow, just had a thought, I could try add a remote-RF alarm option too to the altitude alert, so that you could have it in your pocket and it'll beep when you exceed the preset.

Paul.
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Old Feb 05, 2011, 12:03 AM
PLD
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Haven't had word yet from the PCB factory, though I would expect them to have the boards ready to ship this week.
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Old Feb 05, 2011, 02:38 AM
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G'day Paul, great idea mate. My thoughts would be the rf alarm in your pocket would be much more useful than trying to spot a led at height. Keep it up though :-) I'm forever wondering 'how high is my model?'
Cheers Matt

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Originally Posted by pldaniels View Post
Hey there folks, just back in finally after being 'lost' for a week due to TWO cyclones hitting the coast during the week.

Anyhow, just had a thought, I could try add a remote-RF alarm option too to the altitude alert, so that you could have it in your pocket and it'll beep when you exceed the preset.

Paul.
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Old Feb 05, 2011, 04:04 AM
PLD
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Phoenix,

I'll be offering a swathe of variants. The integrated LED unit will likely be the cheapest option, the RF version going for moderate amount more, such is the unfortunate nature of more features

The real proof of usefulness is going to be when I finally get my hands on these boards and get to build the first couple.

Paul.
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Old Feb 06, 2011, 02:47 AM
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I will be watching developments here Paul....very handy.
Another electronic idea suggestion.....
A friend asked me today if I knew of a warning device that amounts to a stall warning!!! Both he and I (mature years) can let a model on final approach (Flying towards ourselves) get too slow, and cause a tip stall. Nasty. Thinking about it, all we need is a speed device on similar principles to the altimeter. IE, we pre-set a speed, and it sounds an alarm if the model drops below that speed. Something to think about anyway
Cheers,
Adrian
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Old Feb 08, 2011, 02:17 AM
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Thanks for the update Paul. Good work on these inovative RC electronics :-)

Cheers,
Matt

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Originally Posted by pldaniels View Post
Phoenix,

I'll be offering a swathe of variants. The integrated LED unit will likely be the cheapest option, the RF version going for moderate amount more, such is the unfortunate nature of more features

The real proof of usefulness is going to be when I finally get my hands on these boards and get to build the first couple.

Paul.
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Old Feb 08, 2011, 03:36 AM
PLD
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Still no sign of the PCBs yet - I dare say that I won't hear anything until about the 11~12th (as the factories probably don't come back online for a day or so after the end of the Chinese New Year).

Paul.
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Old Feb 09, 2011, 03:30 PM
PLD
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Boards have been FedEx'd ... another 5 days they might be here.
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Old Feb 13, 2011, 11:47 PM
PLD
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Boards have arrived.

I've hand-assembled one, so far the pressure sensor is showing up quite good - giving me 3.90V which translates to 97.22kPa which in turn translates to 390~400m altitude which is correct for this area (the airport is at 1300' ~ 396m).

Now, that was the easy bit... the hard bit is going to be ensuring that the analysis of the voltage (3.90V etc) is done correctly by the opamp and AVR combination.

Paul.
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