Do you need the diode for SSR? Or just mechanical coils and relays?
Mike
On Jan 25, 2017, 10:04 AM, at 10:04 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
Thank you David!!!
From: David Erbas-White<mailto:derbas@xxxxxxxxxxxxxxxx>
Sent: Wednesday, January 25, 2017 9:56 AM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: Resistance for Electric Matches
On 1/25/2017 9:38 AM, R Dierking wrote:
Richard,
Ground to brown, positive to yellow. That's not a resistor, it's a
diode and it's hooked up 'backwards' in order to snub the voltage spike
that occurs when you remove the voltage from the solenoid. Otherwise,
it can harm the electronics that you use to apply the voltage. If you
hook up the power supply backwards, you will blow out that diode
(instantly).
DO NOT remove the diode, it won't harm anything.
David Erbas-White
Thank you for posting the link James. Really good read. The info for
figure 4 was interesting and showed the “conduction current of the gas
plasma produced by the burning pyrogen.” Also, the section on using 9
volt batteries was good.
Hopefully, I can go a little OT now and ask about the wiring for some
miniature solenoids I’ve acquired. Please see the attached photo. The
solenoid has a marking that it can be powered by 22 to 30 VDC. The
wires are yellow and brown. Do you know what the polarity would be?
Also, there’s a small resistor across the leads. Without me guessing,
what is the purpose of this resistor and should the solenoid work
without it? Is this the kind of thing that may improve the performance
of e-matches?
Thank you,
Richard Dierking
From: James Dougherty<mailto:jafrado@xxxxxxxxx>
Sent: Tuesday, January 24, 2017 9:22 PM
To: ROC Chat<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: Resistance for Electric Matches
And yeah Richard, what Kurt said.
On Tue, Jan 24, 2017 at 9:21 PM, James Dougherty
<jafrado@xxxxxxxxx<mailto:jafrado@xxxxxxxxx>> wrote:
hey great thread.
Old. but good - not sure if you guys read Rob's ignitor testing ...
https://web.archive.org/web/20121119015627/http://www.gwiz-partners.com/igniters.pdf
You'll find the DF N28F is very much equivalent to an MJG J-tek and
there is a good
reason for that - your standard Automotive airbag used to have 2 of
these babies in it.
Kind of crazy when you think that in an accident you're Airbag
deployment is relying
on 2 Ohms of load and a one dollar e-match. :-)
On Tue, Jan 24, 2017 at 3:23 PM, Chris Spurgeon
<chris@xxxxxxxxxxxxxxxxx<mailto:chris@xxxxxxxxxxxxxxxxx>> wrote:
I wonder if it could also be the case that at the instant when one of
the igniters burns through, all of them are already so hot that they’ve
reached a point of no return and are going to ignite even without
further electric current?
On Jan 24, 2017, at 1:02 PM, R Dierking
<applerocketry@xxxxxxxxxxx<mailto:applerocketry@xxxxxxxxxxx>> wrote:
Yup, I know, hard to believe series is better. But, it is. It took a
lot of convincing (Allen) and testing for me to swallow that, but it
works great.
However, you have to test before you launch! I provided test points on
the airframe to test the amount of resistance of the series before
launching.
Now, if I could only get the damn hatch to blow off. ☹
From: Alexander Jones<mailto:uscjones@xxxxxxxxx>
Sent: Tuesday, January 24, 2017 12:06 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Cc: R Dierking<mailto:applerocketry@xxxxxxxxxxx>; Chris J
Kobel<mailto:chris.j.kobel@xxxxxxxx>
Subject: Re: [roc-chat] Re: Resistance for Electric Matches
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/id/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<mailto: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<mailto:applerocketry@xxxxxxxxxxx>]
Sent: Tuesday, January 24, 2017 11:41 AM
To: Adrian P. Bailey
<adrian@xxxxxxxxxxxxxxx<mailto:adrian@xxxxxxxxxxxxxxx>>;
roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>; Chris J Kobel
<chris.j.kobel@xxxxxxxx<mailto: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<mailto:adrian@xxxxxxxxxxxxxxx>
Sent: Tuesday, January 24, 2017 11:25 AM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>; Chris J
Kobel<mailto: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@xxxxxxxxxxxxx>
[mailto: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<mailto:chris.j.kobel@xxxxxxxx>>;
roc-chat@xxxxxxxxxxxxx<mailto: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<mailto:chris.j.kobel@xxxxxxxx>
Sent: Tuesday, January 24, 2017 10:53 AM
To: R Dierking<mailto:applerocketry@xxxxxxxxxxx>;
roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: RE: [roc-chat] Re: Resistance for Electric Matches
Sticks and stones….
From: R Dierking [mailto:applerocketry@xxxxxxxxxxx]
Sent: Tuesday, January 24, 2017 10:51 AM
To: Chris J Kobel
<chris.j.kobel@xxxxxxxx<mailto:chris.j.kobel@xxxxxxxx>>;
roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: RE: [roc-chat] Re: Resistance for Electric Matches
Wow, not bad for a wire twister Chris. 😊
From: Chris J Kobel<mailto:chris.j.kobel@xxxxxxxx>
Sent: Tuesday, January 24, 2017 10:33 AM
To: roc-chat@xxxxxxxxxxxxx<mailto: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@xxxxxxxxxxxxx>
[mailto:roc-chat-bounce@xxxxxxxxxxxxx] On Behalf Of R Dierking
Sent: Tuesday, January 24, 2017 10:08 AM
To: Andrew Wimmer
<xenonrocket@xxxxxxxxx<mailto:xenonrocket@xxxxxxxxx>>;
roc-chat@xxxxxxxxxxxxx<mailto: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<mailto:xenonrocket@xxxxxxxxx>
Sent: Tuesday, January 24, 2017 9:56 AM
To: roc-chat@xxxxxxxxxxxxx<mailto: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<mailto: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
