GPS
FLIGHT |
| After an appropriate amount of
whining, my wife got me a GPS/Flight for my birthday in July 04.
Baddaboom was heading four miles up that summer and I knew we had
reached the limit of visual observation and that the rockets were
getting too expensive to lose. We ordered the PK-STXe-USB
package and added a micro-action board and the digital altimeter |
GPS Flight in foam block for
3" nosecone
|
Of course, like many other
things you buy, accessories are required. The GPS Flight displays
position in degrees with five decimal places. We needed a hand-held GPS
that had a large display (so I could see it without reading glasses) and
could display both degrees, minutes, seconds and degrees with 5 decimal
places. West Marine sold us the
Garmin 76S. |
Garmin 76S with
windshield antennae and car power adapter
 |
We're pretty happy with the
GPS/Flight. Baddaboom flew across the road at October Skies 04 and
(other than up) no one had a clue where it went. We loaded the data from
100' into the Garmin and set off. We followed the road, hiked for awhile
and battled brush for a while. When the Garmin beeped "approaching
destination" I saw the rocket. It was in a field 1.5 miles away in
7' high brush. It would have been lost without the GPS. |
The Dashboard software
running on the laptop is very cool with altimeters and speedometers. We
usually leave the laptop in the car and record a file of each flight.
You even get a plot of the rocket walking to the RSO table, then walking
to the launch pad and eventually flying. The files are pretty easy to
access with Notepad, so you can edit out the down-time and relive the
flight later. |
| The
GPS/Flight has pretty specific voltage requirements and we had a little
trouble at start-up. You have to use 4 NiCad's to keep the voltage under
5V. We did buy the switched, (4)AAA holder with our unit, but we had a
shorted AAA. The unit started up and the LED's blinked as normal, but we
had no communication to the receiver. The GPS will operate at 3.6V, but
the radio quits at 4.2V. |
Our 5 Volt power supply
|
The (4) AAA's run the unit for
about 4 hours if you lower your transmit rate to 1/sec. We never got
friendly with the NiCad's and recharging, so we made a little power
supply that lets us use a 9V Alkaline battery. The power supply uses a
series regulator, an over-voltage clamp and runs for 2 hours and 15 min.
on a fresh 9V battery. You can get back to the original 4 hours with (2)
9 Volt batteries in parallel. |
| Power supply parts list:
9 Volt battery clip w/ wires
LM7805 Series Regulator
1N6373 Transient voltage clamp
4.7 mfd/35V Capacitor
|
Schematic 5V power supply
 |
Assembly
No rocket science here. Identify the leads and solder the clamp and
cap to the regulator. Don't omit the cap, the 7805 is a switching
regulator and produces output noise. Add the wires and cover the whole
thing with shrink tube. Check for +5V output before connecting to
GPS/Flight. |
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