Advertisement
Mounting Your Eggtimer Proton
IMPORTANT: Your Proton must be mounted so that the "UP" labels on the board are
pointed towards the nose cone of your rocket!
The Proton is relatively small and light, and can be mounted several ways. The most common
way of mounting it is using four #4 screws, either self-tapping screws for wood sleds (put a drop
of CA glue in the hole first to prevent the screws from loosening in flight) or machine screws
(we recommend using Nylon-insert nuts so they don't come loose). We recommend that you use
Nylon washers between the board and the screw heads to prevent any possibility of shorts.
You'll also need to put some kind of spacer between the bottom of the board and the sled, about
3/16" high. There's a mounting template on the Eggtimer Rocketry web site to help you plan
your installation.
We do NOT recommend using double-sided foam "servo" tape to mount the Proton to your AV
sled. There are parts on both sides of the board, so the bottom isn't flat. You won't get 100%
coverage with the servo tape, so there's a potential for it coming loose in flight, which is bad.
Also, when you pull it off, you might lift a part off the PC board... that would be bad too.
However you mount it, be careful not to overtighten the screws and possibly bend the circuit
board. The parts on the bottom of the board can break if you force them against the bottom of
your sled... don't ask us how we know. We recommend that you leave a little space between the
board and the sled... about the thickness of a credit card.
The Proton should be mounted so that the "UP" markings near the WiFi module face the nose of
your rocket. You also want to make sure that the holes are drilled properly so that it faces as
vertically as possible. If you get it a tiny bit crooked it's not going to matter much, but the more
care that you put into the mounting the better your results will be.
Since the Proton primarily uses a barometric pressure sensor to determine altitude, you'll need to
drill a few holes in your AV bay to vent it to the outside air. There's a lot of debate about what
the right size for the holes is, how many, etc., but the most accepted rule of thumb is: One ¼"
diameter hole for every 100 square inches of AV bay volume. For most average AV bays that's
going to be three 3/32" to 3/16" holes.
Now the tricky part is that you don't want ONE vent hole... the optimum number is THREE,
equally spaced along the AV bay perimeter. This works out to about three 5/32" holes for every
100 square inches of volume. That's just about the size of a 4" diameter AV bay that's 8" long,
so you can work up or down based on that. We also recommend that you don't mount it so that
the pressure sensor is directly across from the vent holes in your AV bay. You can get funny
currents during flight, which may compromise the accuracy of the altitude readings.
Wiring Your Eggtimer Proton
The Proton is designed to have the power connector wires directly soldered to the board, and
outputs connected using the screw terminal blocks. You can also omit the terminal blocks for
the outputs and solder pigtails to the output pads on the board, so you can use whatever method
- 6 -
Advertisement
