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Jan 25, 2004, 04:58 PM
MX
MX
Embedded Systems Engineer
MX's Avatar

Here's how high I flew today.


576 feet, as you can see by my altimeter. This is the prototype
I built. The connector on bottom right is for connecting to the
PC and downloading the altitude logged every second during
flight. The board is mounted on the side of my AP plane. I've
always wondered (and been asked) how high my plane was
when taking pictures. I usually guess about 400 feet, which
was probably pretty close. I went a little higher on this flight
for the altimeter test.

I hope to get a real printed circuit board made up so it will be
much more compact, about 1"x2.5". That ought to fit in the
fuselage of most planes.

MX
Last edited by MX; Jan 25, 2004 at 05:00 PM.
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Jan 25, 2004, 05:52 PM
Registered User
The Other Dave's Avatar
Very cool.

What is it built with as far as componants?

Are you planning on posting a schematic/hex...?
Jan 25, 2004, 06:06 PM
MX
MX
Embedded Systems Engineer
MX's Avatar
It uses a pressure sensor, A/D converter, microcontroller,
LED display, and eeprom.

I'm not sure yet where I'll go with this. I may try to productize
it. A couple of the parts are pretty expensive in single
quantities, so volume may get a better deal. Plus, it's mostly
surface mount parts, a couple having fine-pitch leads. Somewhat
of a challenge to assemble.

Any interest out there if I build these?

MX
Jan 25, 2004, 06:52 PM
Registered User
BAR-STOOL's Avatar
Put me down for 1

I am interested in your 1st one off your production line.


BAR-STOOL
Jan 25, 2004, 07:01 PM
Electric Addict
downeym's Avatar
how much is your target price?
Jan 25, 2004, 07:14 PM
MX
MX
Embedded Systems Engineer
MX's Avatar
Ok, I ran some numbers to see how it would price out. Are you
sitting down? Looks like I'd have to sell for around $80+ to make
it worth doing. That would include the display, the serial cable,
and the PC software. Actually, that's probably pretty competetive
considering it includes all that and logs the data. It would
depend too on what kind of quantity pricing I could get on the
parts. The display and pressure sensor are pretty expensive.

I'd appreciate any feedback anyone has to offer.

MX
Jan 25, 2004, 07:15 PM
SlowStick Test Pilot
patrickegan's Avatar
How much for something a little simpler? Just max alt.
Jan 25, 2004, 07:19 PM
Registered User
BAR-STOOL's Avatar
One question. does it have a reset button to 0 it out on the ground so you could go up again to get some more readings.

BAR-STOOL
Jan 25, 2004, 07:21 PM
Electric Addict
downeym's Avatar
how hard would it be to add another pressure sensor and get airspeed readings also?
Jan 25, 2004, 07:22 PM
MX
MX
Embedded Systems Engineer
MX's Avatar
Like I said, the expensive parts are the display and pressure
sensor, at around $15 each, so for just a device to display
current / max altitude it would probably be around $60. I'm still
looking for a cheaper display. I can go out and buy a calculator
or watch with a display for a few bucks, so if I can find a cheap
supplier of little LCD displays, that would help a lot.

MX
Jan 25, 2004, 07:24 PM
Registered User
BAR-STOOL's Avatar
$80.00 Bucks wow I did not want to buy the cow Just the milk. I think the ALT watch will have to do for me.


BAR-STOOL
Jan 25, 2004, 07:28 PM
Electric Addict
downeym's Avatar
another option would be to use a single LED to blink the altitude.. have 4 LEDs, one for each digit... for example, if the altitude was 1235' it would blink once, wait ,twice, wait, 3 times, wait then 5 times... not fnacy, but the cheapest solution!
Jan 25, 2004, 07:30 PM
Electric Addict
downeym's Avatar
I think most people will just want to know the max altitude too..

The eagle tree system is $150 and will do a lot of stuff. I would concentrate on making it as cheap as possible.. I would aim for <$50...
Jan 25, 2004, 07:34 PM
MX
MX
Embedded Systems Engineer
MX's Avatar
I'll keep working to get the cost down. As pictured above, it's a
pretty high end version. This one can detect changes of one foot,
will log data (at user specified intervals), can measure from below
sea level to over 50,000 feet, PC interface, temperature
compensated, etc. At one measurement per second, it will log
data for over an hour. I wanted mine to do everything I might
need or want.

MX
Jan 25, 2004, 07:39 PM
Electric Addict
downeym's Avatar
you might be able to make a single PCB that can do both... just leave off the LCD and EEPROM and flash a new version of the code... that way you only have to order one board...

Also, if you shoot a board for it, make sure you ask the vendor what size master panel they use. most of the time they will charge you based on this size and you can optimize the board to fit into the panel the most times. You can save a lot of board costs this way too...


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