DD ematches

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Please....consider the potential problems of encouraging the purchase of matches/lighters/whatever that you know aren't shipped properly.

The more folks post publicly about buying this kind of thing via means that are obviously not being shipped properly, the greater the odds of us incurring the wrath of regulatory agencies.

Buy from suppliers who ship the products legally and with proper paperwork and packaging.

-Kevin
 
troj said:
Please....consider the potential problems of encouraging the purchase of matches/lighters/whatever that you know aren't shipped properly.

The more folks post publicly about buying this kind of thing via means that are obviously not being shipped properly, the greater the odds of us incurring the wrath of regulatory agencies.

Buy from suppliers who ship the products legally and with proper paperwork and packaging.

-Kevin
Click to expand...

Any suggestions as to whom? I honestly don't know where to get e-matches that are shipped legally.
 
I just called PyroDirect to see when they might have some more of the 3' Firewire Initiators back in stock. They have some in storage that they have not unpacked, so they do not show in their inventory. They took my order over the phone and they will ship out Monday.
 
Interestingly enough, Pyro Direct is a bit cheaper than buying direct from MJG.

A box of 80 w/ 3 foot leads from MJG is $68 + $9.10 in shipping.

Two packs of 40 from Pyro Direct is $66.40 + $11.75 in shipping.

If you're buying more than one box, though, MJG's shipping stays the same whereas Pyro Direct goes up, and starts to become more expensive.

-Kevin
 
Is there anywhere to get them with 6-inch leads? Three feet is a lot of waste when going from a terminal block to a charge well.
 
Bat-mite said:
Is there anywhere to get them with 6-inch leads? Three feet is a lot of waste when going from a terminal block to a charge well.
Click to expand...

Nope. Just buy with the shortest leads you can and cut the wire off to the length you need.

-Kevin
 
I ordered some of these (125 units for $23.50) on Sept. 8 and they arrived today. Tested a couple and they test right at 1 ohm resistance. Also tested one with my magnetic apogee detector (Zeptomag) and it fired off flawlessely . . . I even used a 9 volt battery that was low on juice.
 
I've tested around 30 of the Chinese ones. Purchased 100.
1.4-1.7 ohms. Zero failures so far.

Is it feasible to use 2 matches per charge canister? I haven't
Tested for that.
I'm running 9.6 volt block batteries per altimeter.

JP
 
On my L3 I run two per canister with RRC3s and 9 volt batteries.
 
Any issues with running these e-matches from a 12v source instead of 9v, or should I step it down? the fire current on the ones I bought (currently in the mail) is 0.4 amps. Assuming 1.5 ohms, that means it should only take 0.6v to fire them. Double or triple that for good measure and you're at 1.8v and 1.2 amps. Firing with 12v would mean there would be 8 amps going through it?! At 9v there would be 6 amps.
 
The ones I have seen shipped as jewelry, toys and electronics.
 
HighFlight said:
Any issues with running these e-matches from a 12v source instead of 9v, or should I step it down? the fire current on the ones I bought (currently in the mail) is 0.4 amps. Assuming 1.5 ohms, that means it should only take 0.6v to fire them. Double or triple that for good measure and you're at 1.8v and 1.2 amps. Firing with 12v would mean there would be 8 amps going through it?! At 9v there would be 6 amps.
Click to expand...

I'm not sure if upping the voltage is a good idea or not. I had two different commercial matches fail on the same flight using a brand new 9VDC battery on my Perfectflite HiAlt45. Both read 1.0 - 1.2 ohms when installed, had good continuity beeps from the altimeter and neither fired during flight. Both showed open after the flight and the altimeter was beeping the altitude like it was a normal flight. I don't know exactly what happened, but to burn the bridge wire without firing the pyrogen is pretty rare. I my gut says it is more likely with higher voltages/amperes since those are more capable vaporizing the small bridge wire too quickly to ignite the pyrogen. With that said, I would think the matches would be designed to work well with 12 VDC or less since that is standard car battery size and most of the matches are used for pyrotechnic displays and fired from the ground.
 
Handeman said:
I'm not sure if upping the voltage is a good idea or not. I had two different commercial matches fail on the same flight using a brand new 9VDC battery on my Perfectflite HiAlt45. Both read 1.0 - 1.2 ohms when installed, had good continuity beeps from the altimeter and neither fired during flight. Both showed open after the flight and the altimeter was beeping the altitude like it was a normal flight. I don't know exactly what happened, but to burn the bridge wire without firing the pyrogen is pretty rare. I my gut says it is more likely with higher voltages/amperes since those are more capable vaporizing the small bridge wire too quickly to ignite the pyrogen. With that said, I would think the matches would be designed to work well with 12 VDC or less since that is standard car battery size and most of the matches are used for pyrotechnic displays and fired from the ground.
Click to expand...

I agree. More is not necessarily better. It is weird to see two matches fail in that manner but say one has a nick in the bridgewire. One certainly isn't going to see that. Resistance could still be normal and when zapped with a high amp current, the nick fails and the rest of the wire doesn't have time to generate
enough heat flux to start the pyrogen. Again, I think this is a rare event with an ematch but like Mr. Hendrickson points out, light off a lot of matches and one will eventually get to a bad one.

A similar thing can happen with homemade motor igniters. Zap one with a lot of amps and one segment of the nichrome wire may heat unevenly and the overlying pyrogen goes "pop", the wire breaks and no flame. Use a partially charged or "spent" car battery or lead calcium one and the element heats up more slowly increasing the chances the pyrogen will flare and not undergo a localized pop.

Now, if one has dipped a batch of motor igniters and find that they pop instead of flare, there's a little trick that may save them. Gently crack the pyrogen transversely along the length of the pyrogen head. Do it gently so you don't get a large amount to fall off. What I believe might be happening is the cracks allow the gases of early combustion of the pyrogen close to the bridgewire to "vent off", avoid popping and prevent an early bridgewire fracture and failure.
Another thought is the pyrogen cracks allow the heat to escape out and spread out over the pyrogen spreading the initiation heat more gradually. It appears sometimes that an igniter with a long pyrogen head, heat starts from one segment with a crack and propagates from there. Kurt
 
just wanted to report back. The e-matches I bought: https://www.ebay.com/itm/141189409470

...finally arrived, 24 days after I ordered them. Set one off remotely with an RC radio and a receiver-controlled switch, connected to a half-charged 500mAh 3-cell LiPo battery. Worked perfectly. Granted this is only ONE, so not enough to draw statistics on.
 
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