I use ematches (as used for fireworks) which are easily available in the
UK, no license required. Being poor I usually use cheap chinese no-name
ematches, apart from the loud crack! noise they work well and reliably.
They vary a little, but normally the stated all-fire is 500mA or 600mA
or 1A, and no-fire is 50 mA - some have a 200mA no-fire, but I have
never come across one with a no-fire of less than 50 mA.
I stick to 50 mA no-fire and 1A all-fire for everything (except for
flash matches, which need a higher fire current) and haven't gone wrong
yet.
However that is from a user POV, from an ematchmaker POV I suppose
something like 250mA no-fire and 400mA all-fire is probably a good target.
For quicker ignition and good timing I tend to use about 2-3A actual
firing current.
LED continuity testers usually use around 2mA.
Ematches come with wires attached which vary in length from 0.5m to 3m.
They have plastic shrouds on the heads to prevent damage and unwanted
ignition from impact or the next one in a bundle going off.
Short ones are about 15p, long ones are about 60p each in 100's.
They are sold and stored with the far ends of the wires twisted together
to short them. I have never had one go off due to static or EM fields,
and I don't know anyone who has, but it's a cheap safety measure.
You can legally (in the UK) and practically attach them to fireworks set
up in the place where they will be used, and wire them up, the day
before a display. You can't transport ematched fireworks.
They might need some boosting to ignite a large solid, but they ignite
fairly large gunpowder rockets just fine on their own.
On that note, they might be used to ignite eg 10" shells or larger in a
display; they are used (often with double match and wiring) on some
really big parts of the biggest displays - compared to which most
amateur rockets are small stuff.
If I may digress, the cheap ones make a crack! which leads me to believe
they detonate the part closest to the wire which then blows the middle
layer out as burning stuff (the outer layer is plastic waterproofing or
the like). Quiet ones are available but are more expensive.
Sadly I hear ematches are not easily available in some other places than
the UK.
HTH,
Peter Fairbrother
On 05/01/2021 21:00, Dr Edward Jones wrote:
Pretty sure Estes rates their igniters, but I seek a broader base of do-it-yourselfers' wise advice. In my dreams, an igniter will NO-fire with a LED test circuit powered by a hearing aid or watch battery, yet certainly fire with an old-fashion Western Electric 6-vdc Blue-Bell dry cell. I'm hoping to sure-fire ignite at 9-vdc by "small radio cell." What's common practice with small battery ignition, even with a relay?
Thanks again
On Tue, Jan 5, 2021, 13:12 Dr Edward Jones <RocketPioneer@xxxxxxxxx <mailto:RocketPioneer@xxxxxxxxx>> wrote:
Thanks. Want to know what's commonly in practice among thinking
amateurs with commonly used batteries other than car batteries.
On 1/5/21, George Herbert <george.herbert@xxxxxxxxx
<mailto:george.herbert@xxxxxxxxx>> wrote:
> Those would include role (NASA/Space? Military? Amateur?), both
arbitrary
> (static electricity, accidental connection to wall currents etc)
and system
> specific failure modes that need tolerating.
>
> For amateur stuff, with igniters typically not shipped installed &
> disconnected leads until firing, no fire on typical high end static
> discharge is probably good enough.
>
> There are military and NASA specs published if you need to refer
to them.
>
> -George
>
> Sent from my iPhone
>
>> On Jan 5, 2021, at 11:48 AM, Dr Edward Jones
<RocketPioneer@xxxxxxxxx <mailto:RocketPioneer@xxxxxxxxx>>
>> wrote:
>>
>> Are there 'best practices' or usual standards for NO-fire and
>> SURE-fire power for amateur solid rockets? I'm developing some
>> atypical bridgewires. Thanks.
>>
>> Edward in Socorro
>>
>
>