Download Building a BASIC Stamp I Flight Computer (Powerpoint)

Building a BASIC Stamp I
Flight Computer
(Paul Verhage design)
AEM 1905, Fall 2008
The main item – the homemade (etched
and drilled) printed circuit board (PCB).
Use the circuit layout diagram to help place
components on the printed circuit board.
Here are the sockets, 3-pin male header,
and row of female receptacles.
Here is the BASIC Stamp chip and three
other chips – ask for these once your
board is completed and checked.
Begin building cable connectors by cutting
your ribbon cable in 4 equal pieces then
separating the individual wires.
Take the four green wires and lay them out
with a micro-plug. Shrink wrap color, not
wire color, will indicate polarity.
Plug the micro plug connector together then
use the Helping Hands to hold the wire in
place. Be sure to heat sink the opposite pin!
Solder on each of the 4 wires (gently!) then
add the shrink wrap (watch the colors!).
Here is the connector when separated.
Repeat, making a white, red, and black cable
connector as well. These fit together both
ways so the shrink wrap will indicate polarity.
Notice that your 14-pin socket is actually
half of a 28-pin socket, cut apart for you.
Use your utility knife to cut out three 3 x 2 pin
sections of female receptacle. Cut wide (i.e.
waste 1 set of pins with each cut).
The sockets, 3-pin header, and female
receptacles will go into the non-copper
side of the PCB.
Using the circuit layout diagram, place
them all to make sure they fit the holes.
Start soldering just the sockets – they all
stick up the same distance so you can
solder with the PCB flat on the wood.
Always pause to examine your soldering for
solder bridges and/or poor connections.
When soldering in the 3-pin header, the
short pins go through the board. Heat
sink the pins one by one, as shown below.
Here is the PCB with the four sockets, the
3-pin male header, and the three sets of
female receptacles soldered into place.
Add the three 1k resistors. Notice that
one of them stands on end.
Starting now, clip off excess leads on the
copper side of the board. (Sockets and such
didn’t need clipping – their pins are short.)
I ran out of 2.2 k resistors so make one
by putting a 1k and a 1.2 k resistor in
series. First twist the leads like this.
Then solder the twist together and clip
off the excess wire on that end.
The two 2.2 k (combination) resistors go
into the PCB on end as well.
Insert the electrolytic capacitor, watching
the polarity (+ is marked on the diagram
and – is marked on the capacitor itself).
Carefully bend the legs of the 5-V voltage
regulator, as shown below.
Insert the voltage regulator. The metal
plate (its own heat sink!) should lie flat
on the PCB.
Use a machine screw to heat sink the
voltage regulator to the PCB. We’ll use a
Dremel tool to cut off the excess bolt.
Cut the black jumper wire into 4 pieces, strip
the ends, bend them into a “U” shape.
Insert the jumpers at the four locations
indicated on the circuit layout diagram.
Add cables for the switch (red), battery
pack (white), and indicator LED (green).
Polarity is critical on the last two.
Use the black cable for the pull-beforeflight connection. Polarity doesn’t matter.
Attach the other end of the white cable to
the battery pack. Be sure to match polarity!
Insert the switch into the switch plate
and use hot-glue to hold it there. Solder
the red cable to the switch.
Insert the LED into the switch plate and
use hot-glue to hold it there. Solder the
green cable to the LED, watching polarity.
Use a wire to short-circuit the audio plug,
then reassemble it.
Insert the audio jack into the switch
plate and use hot-glue to hold it there.
Use a multimeter (on the resistance setting)
to figure out which two legs of the audio
jack get shorted when the plug is inserted –
attach the black cable to those two legs.
Have your flight computer board inspected
then get your BASIC Stamp and three other
chips and insert them (the right way around).
Connect your flight computer to your battery
pack and switch plate. We’ll put batteries in
and test them and program them as a class.
Here is a light plastic backing (like Correplast)
for the flight computer.
Use zip ties to attach the backing to the PCB
(to cover up the soldering – this will require
drilling some more holes) then put velcro on it
(to attach the computer in the payload box.)
Incorporate the switch plate permanently into
one side of your payload box. Make sure your
cables will reach to the flight computer and
the battery pack, both of which will be
attached inside the payload box with velcro.