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of terminating the connections you want: barrier strips, solder directly to pigtails, through-
bulkhead terminals, etc. Soldering connections to the board prevents the connections from
coming loose in flight due to vibrations and G-forces.
We've found that simply wire-wrapping the igniters to a "pigtail" wire soldered to the board
works very well for smaller rockets. By soldering the pigtails to the board rather than having
screw terminal blocks, you eliminate the possibility that the wire may work loose from the
terminal in flight. It saves space too, which is usually at a premium with 38mm and skinnier
rockets. We also like the wiring kits sold by Binder Design Rocketry, the wire they supply is
Teflon-jacketed and lends itself well to solder-type wiring. Their charge wells with integral
through-bulkhead terminals als work great for 39mm-54mm rockets.
We recommend using #22-#26 gauge wire for wiring to the Proton board, we like to use the #24
gauge stranded wire that's found in Cat-5 network cables. It's cheap, easy to find, and just the
right size. It's also twisted together in nice solid-striped pairs, so it's easy to tell the "+" from
the "-" wire. If you can, get the "plenum" cable, since it has a Teflon jacket and doesn't melt as
easily when you solder to it as the standard "riser" cable. You can also use solid wire, but solid
wire is harder to work with and has a tendency to break after being bent a few times. These
breaks can be a pain to find, because they are typically inside the insulator jacket where you
can't see them.
If you use stranded wire, you MUST TIN THE WIRES BEFORE SOLDERING TO THE
BOARD. This is to prevent stray "whiskers" of wire strands from coming loose and bridging
pads, or breaking off and landing on the board in some random place. We've seen the results of
this happening, it's not pretty, and they can be very hard to find if the lodge underneath the
processor chip or in some other hidden spot on the board.
If you build the board with the terminal block option, be sure to tin whatever wires you are using
for your igniters before you insert them into the terminal block. Loose strands here can prevent
deployments, if a strand comes loose and lodges in the wrong place it could cause an immediate
deployment when you connect the battery. That would be bad...
Last, but not least, we strongly recommend that all wiring on your sled be zip-tied to the sled so
that there's no chance of any wires coming loose in flight. We've seen it happen, and the results
are not pretty.
The Single-Battery Option
For a single battery, you only need to solder a jumper (or switch, see below) between the B+ and
DP+ pads that are located next to the two BATT pads. This will provide power to the
deployment circuitry directly from the battery. Nothing else is necessary... see the picture below.
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