Most commercial electric matches will reliably fire when wired in series.
We don't know what brand Richard's are, so it's hard to say for sure
though.
"Firing more than one electric match per cue": http://www.skylighter.
com/fireworks/how-to/wire-fireworks-displays.asp
Last paragraph: http://wrtiii.net/wordpress/?page_id=122
"4. Series wiring": http://www.pyromate.com/Basics-of-Electrical-Firing.htm
-Andrew
On Tue, Jan 24, 2017 at 12:06 PM, Alexander Jones <uscjones@xxxxxxxxx>
wrote:
Excuse me if I'm misunderstanding the situation, but wouldn't it be a bad
idea to wire them in series? Bc they're designed to kill their own circuit
(or at least add a LOT of resistance to it) when they blow, so if you're
trying to get more than one charge to blow, and they're not backups to each
other (i.e. you need all of them to fire), you'd have one blow, then the
current would drop drastically across the other two and they may not
fire....I would think it'd be better to wire them in parallel so they all
have current available to them at all times, then just limit the current
with a resistor, or, if your concern is destruction of your electronics,
then put some other kind of current limitation circuitry in the line....
something like this: http://www.instructables.com/i
d/World-simpliest-DC-current-limiter/ ....if you don't want to drag
yourself through the math to get the fixed resistor value analytically (so
you don't have a potentiometer in your rocket), you could build the circuit
first with the potentiometer in place to determine what resistance = the
current you want, then replace it with an equivalent fixed-value resistor.
It's a decent amount of work, but it's better than destruction of your
avionics board due to overcurrent or a recovery system failure on what I
assume is a pretty big project, if it has 3 parachutes.
....or just check and see if your avionics board has a current limiter or
overcurrent protection built in....some of them do.
On Tue, Jan 24, 2017 at 11:43 AM, Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx
wrote:
This may be a silly question but have you tested the resistance of the
test leads (by holding the ends together)… ;)
*From:* R Dierking [mailto:applerocketry@xxxxxxxxxxx]
*Sent:* Tuesday, January 24, 2017 11:41 AM
*To:* Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx>; roc-chat@xxxxxxxxxxxxx;
Chris J Kobel <chris.j.kobel@xxxxxxxx>
*Subject:* RE: [roc-chat] Re: Resistance for Electric Matches
Looks like the San Marcos store for me.
Are Cat 3 test leads OK for our purposes? Perhaps I just need better
test leads with clips?
*From: *Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx>
*Sent: *Tuesday, January 24, 2017 11:25 AM
*To: *roc-chat@xxxxxxxxxxxxx; Chris J Kobel <chris.j.kobel@xxxxxxxx>
*Subject: *[roc-chat] Re: Resistance for Electric Matches
Fry’s in Woodland Hills has quite a selection. Check online – it will
tell you what they have in the store nearest you: http://www.frys.com/
*From:* roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@freeli
sts.org <roc-chat-bounce@xxxxxxxxxxxxx>] *On Behalf Of *R Dierking
*Sent:* Tuesday, January 24, 2017 11:20 AM
*To:* Chris J Kobel <chris.j.kobel@xxxxxxxx>; roc-chat@xxxxxxxxxxxxx
*Subject:* [roc-chat] Re: Resistance for Electric Matches
OK, JK, but RSO’s, if you ever see wires sticking out of one of Chris’s
rockets… 😲
He does know his igniters!!!
So, glad I asked about this before conducting my ground test. I had 2
matches with 1.6 ohms and one that was 3.2 ohms that would have invalided
my test. Particularly bad if I would have found out about this later.
Learned: When doing multiple charges in series measure each match (or
igniter), and then all together to check for problems.
Going OT a bit, but does a place like Fry’s have a good selection of
meters? I wonder if I can get a meter that reads resistance better. Maybe
the leads have to be higher quality too?
*From: *Chris J Kobel <chris.j.kobel@xxxxxxxx>
*Sent: *Tuesday, January 24, 2017 10:53 AM
*To: *R Dierking <applerocketry@xxxxxxxxxxx>; roc-chat@xxxxxxxxxxxxx
*Subject: *RE: [roc-chat] Re: Resistance for Electric Matches
Sticks and stones….
*From:* R Dierking [mailto:applerocketry@xxxxxxxxxxx
<applerocketry@xxxxxxxxxxx>]
*Sent:* Tuesday, January 24, 2017 10:51 AM
*To:* Chris J Kobel <chris.j.kobel@xxxxxxxx>; roc-chat@xxxxxxxxxxxxx
*Subject:* RE: [roc-chat] Re: Resistance for Electric Matches
Wow, not bad for a wire twister Chris. 😊
*From: *Chris J Kobel <chris.j.kobel@xxxxxxxx>
*Sent: *Tuesday, January 24, 2017 10:33 AM
*To: *roc-chat@xxxxxxxxxxxxx
*Subject: *[roc-chat] Re: Resistance for Electric Matches
Some info on igniters that I gathered a few years back.
Chris
*From:* roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@freeli
sts.org <roc-chat-bounce@xxxxxxxxxxxxx>] *On Behalf Of *R Dierking
*Sent:* Tuesday, January 24, 2017 10:08 AM
*To:* Andrew Wimmer <xenonrocket@xxxxxxxxx>; roc-chat@xxxxxxxxxxxxx
*Subject:* [roc-chat] Re: Resistance for Electric Matches
To be honest, I don’t know the brand. They are not in the box. They are
however the same color lead wire (black) and appear to be the same make. A
single one is 3.2 ohms.
Richard
*From: *Andrew Wimmer <xenonrocket@xxxxxxxxx>
*Sent: *Tuesday, January 24, 2017 9:56 AM
*To: *roc-chat@xxxxxxxxxxxxx
*Subject: *[roc-chat] Re: Resistance for Electric Matches
What brand electric match?
3 in series should have 3 times the resistance of a single match.
http://www.pyromate.com/Basics-of-Electrical-Firing.htm
-Andrew
On Tue, Jan 24, 2017 at 9:45 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
What’s a good range for the resistance of electric matches?
For my project, there will be 3 parachutes deployed from separate
side-bays and initiating the charges at apogee.
Connecting the matches up in *series* and testing today.
I know the resistance will go up with the series connections, but would
like to get an idea what the range should be.
Thank you,
Richard Dierking
