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If you use a separate deployment battery, remember that you will not see continuity on either
channel until you power on the deployment battery. If you use a switch, we recommend that
you turn it on to test igniter continuity at your work table BEFORE you add the pyro powder to
your charge wells, then shut it off until you're safely on the pad. Turning on the deployment
power does NOT power on the deployment FET; it only allows the trickle current to go through
the circuitry to test continuity.
About Switches...
The Proton is designed so that it will not self-arm itself. If you power it up, it will sit there on
the Status page forever, changing the validation code every 60 seconds... you have to actually
arm it using the validation code in order to start a flight. In addition, the unique dual-ended
deployment output prevents any significant current from getting to the igniter until it's armed
and actually in-flight.
Because of this, for most flights using electronic deployments up through NAR/TRA Level 2
you do not necessarily need a separate power switch if you're using the single-battery option.
You can simply connect the battery to a locking connector such as a JST connector and you're
ready to go until you arm it on the pad. This makes your AV bay build easier and smaller, and of
course it makes your pre-flight procedure a lot simpler.
The Proton is different than most other altimeters because it has dual-ended switching on the
deployment outputs: BOTH the "+" and the "-" side are switched off, leaving the igniter
essentially dead until it's actually in flight (except for a tiny trickle current that's used to test
continuity). For the igniter to fire, both sides have to be activated independently, and this can't
happen until you're in the air and the deployment enabling logic has been triggered.
This meets the NFPA and Tripoli/NAR requirement that pyrotechnics be de-energized until
ready for flight. However, FOR LEVEL 3 CERTIFICATION FLIGHTS ONLY you may need
to add a switch to the pyro outputs. As of the date of publication (Sept. 2018) Tripoli allows
electronic switches for L3 certification projects, subject to the approval of the TAP's. NAR
requires a mechanical disconnect for L3 certification flights.
In the event that you do decide to add a switch, you have a few options, since the Proton can use
a separate power supply for the deployment devices.
If you are using a single battery for both the computer and the deployment side and you need to
use a deployment disconnect switch, you can simply put a switch between the B+ and DP+ pads
instead of a jumper. Turn on the switch when you're on the pad to power up the igniters,
confirm that everything is OK, then arm your Proton and go.
If you are using a separate battery for the deployment side, you can put the switch in series with
the deployment power that goes on the DP+ pad. This is our recommended configuration for
Level 3 rockets because having the separate deployment battery 100% prevents any kind of
deployment glitch from affecting the flight computer side. Doing it this way allows you to
make whatever changes you may need to make (for example, lowering the Main deployment
altitude if the wind picks up a bit) while leaving the deployment side powered off.
Whatever switch you use, make sure that it can handle the expected G forces that you expect the
rocket to experience during flight. In general, we recommend that if you use a slide switch that it
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