Most excellent! Sounds like you all are off to a great start.

For connectors, a JST would probably be fine but I’d think about using a 
terminal block, like one of these:

There are a few other “gotchas” when using an accelerometer, some of which 
you’re probably already familiar with. We can chat more about those off-list, 
or in person sometime. Let me know if you have any other questions!


Wilson Alness<><>

From: Aaron Baker []
Sent: Thursday, November 10, 2016 3:05 PM
To: Wilson Alness; psas-team
Subject: Re: [PSAS] Question for amateur rocketers

We're using a single-cell LiPo, and using a FET to control. A current-limiting 
resistor is gonna be in there!

By "connector" I mean the electrical connector on the board with which we can 
attach leads to the igniter. I was thinking a JST connector or something but 
there's probably a better way. Right now we're planning on using accelerometer 
to control.

Point very well taken on testing!

Thanks Wilson!

On Thu, Nov 10, 2016 at 2:52 PM Wilson Alness 
<<>> wrote:
What sort of battery are you using, LiPo? If you’re using a FETS switch for 
your pyro outputs, you’ll need a resistor otherwise you’ll fuse them shut on 
power-up. As you might imagine this creates a very dangerous situation when you 
have charges hooked up.

Judging only off your demographics, your plans for current sound fine, but 
there are other factors to consider too like what voltage is required for your 
emtaches to fire. 3.3v is probably enough for many, but not all. What type of 
“connector” are you referring to? I’m also curious if you’re using barometric 
or accelerometer.

And test, test, test! I’ve seen far too many expensive lawndarts as a result of 
people flying homebrew recovery systems without testing them.


Wilson Alness<><>

 On Behalf Of Aaron Baker
Sent: Thursday, November 10, 2016 2:45 PM
To: psas-team
Subject: [PSAS] Question for amateur rocketers

I'm trying to design a firing circuit for use on an amateur rocket avionics 
board, for deployment of some kind of device during a flight. The primary use 
is probably parachute deployment, but I could imagine other uses like staging. 
I have a couple questions:

-What kind of current would be useful to have? I'm shooting for a couple 
hundred mA at 3.3 V, but that's just a guess. Need to know for my cap and 
transistor choices.
-What kind of connector would people expect to see in that context?

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