Firing System : Help Needed

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Lloyd
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Re: Firing System : Help Needed

Post by Lloyd »

I don't see the reference zener in that diagram you supplied. Where is it? In that diagram you posted, all the 'ground' references are still at ground.


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Re: Firing System : Help Needed

Post by sambo »

yep, the reference is now ground as now I'm using your method there is no voltage drop to get in the way ? Am I seeing that wrong ?
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Re: Firing System : Help Needed

Post by Lloyd »

OK.. I'm probably confused. Give me an hour or two to absorb the new schematic... dinner's being served, and I'm not as attentive as I should be.

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Re: Firing System : Help Needed

Post by sambo »

Thanks Lloyd ! I know the feeling !

I've been looking into batteries for the firing side and I have found there is an entire trade dealing with Clansman ex-military 24v 5Ah rechargeable batteries such as these :

http://www.ebay.co.uk/itm/Clansman-rech ... SwImRYPAVQ

what do you honestly think ?
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Re: Firing System : Help Needed

Post by Lloyd »

Sorry, Sam.

I had just ONE more thing to do before supper, and ended up slightly injuring a shoulder moving some office furniture -- so I didn't get supper OR get to look at your schematic until this a.m.

That looks pretty good, I think, and although the parts count is a little more, it's conceptually and schematically 'cleaner' than how I first envisioned the change, while accomplishing the same end.

If your +V power supply would be damaged by back-feeding it an over-voltage through 5.6K, you could add a blocking diode between V+ and the common ends of R1, R3-R10, such that the firing supply cannot feed the logic supply. Just anode to V+, and cathode to the commons of that resistor network.

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Re: Firing System : Help Needed

Post by Lloyd »

"http://www.ebay.co.uk/itm/Clansman-rech ... SwImRYPAVQ

what do you honestly think ?"
-----------------------------------

Well first of all, I see they refuse to post to the US. That's good, because with a name like "Clansman", they'd probably all get thrown overboard at the port, anyway!

I don't know, Sam. So much depends upon the age of a battery, even if it has never been used. Some "new old stock" things are great. Others are trash.

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Re: Firing System : Help Needed

Post by sambo »

"Having spent several more days I have essentially arrived at the same problem with referencing to ground and the circuit yields erratic results. I really need to build a voltage ladder I think as you initially described. Or perhaps I should take a break and actually go and do some pyro - might be better !"
00000000000

Man! Sensing shorts vs. "very low resistance" is a 'delicate' operation. Best to make some pyro for a while, and just 'think on it'. Even my 'diode ladder' idea may not be accurate-enough. Across an array of tolerances of components, it might not be possible to correctly sense a dead-short relative to a 0.1ohm resistance.

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Re: Firing System : Help Needed

Post by Tyvole »

Personally, I think you're on a hiding to nothing trying to differentiate. You would need a four-wire connection at the load and the capability to accurately measure a handful of millivolts, so it's not practical in the field. Taking measurements at any sensible distance away from the load or on the other side of any connections and the test results would be nonsense. Sure, a dead short would mean an inconvenient failure to fire at the required time, but even if the failure was not obvious, the post-show inspection should reveal this so that appropriate action can be taken. If correct procedures are followed, it's a fairly safe failure mode. Just my halfpenny worth.
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Lloyd
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Re: Firing System : Help Needed

Post by Lloyd »

I agree.

Sensing a dead-short AT THE BOX might be reasonably done with precision components. Sensing it over 30M of shooting wire, not so much.

FWIW, a VERY brief visual inspection of an ematch head will usually reveal if it's been shorted by a crossed-over lead wire or a solder bridge.

It very rarely happens that the solder bridge is AT the resistance wire crossover (of course, under the comp, so invisible), but most shorted matches I've discovered were shorted in the general vicinity of where the leads attach.

I'm remiss for not having mentioned this earlier, and might have caused Sam more work than it was worth to try... <sorry>


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Re: Firing System : Help Needed

Post by sambo »

ok, well no apology required and Tyvole that's the kind of advice i need. So ! if i scrap the short sensing I have just halved my board cost by doubling the no. of available channels and i don't need the multiplexer ! so a new much simplified schematic coming up !
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Re: Firing System : Help Needed

Post by Tyvole »

Glad I could help, Sam. There's a reason that the main players don't bother to look for short-circuits. I don't know much about firing systems, but back in the day I was a test gear repair and calibration guy. Measuring low resistances is tricky, comparing them, even harder. Even something as daft as a kinked wire could throw off your measurements. To my mind, as Lloyd suggested, visually checking for shorts during rigging and electrically for continuity is the way to go.
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Re: Firing System : Help Needed

Post by sambo »

Well thanks as I now have a working prototype of sorts. There are a couple of issues I need to fix. The first is adequate decoupling and I'm going to need to decouple the 24v firing supply - I'm not really sure how I should go about this so I guess I have some more reading to do.

Lloyd, Infineon make a 24V version of their high side switch and I'll be using a 24V supply ( see here : http://www.infineon.com/dgdl/Infineon-B ... 8da0081a8d ) However, my feeling is that the IC we have chosen ( BTS5020-2EKA ) is more than adequate and can be safely run with a 24v supply under these conditions. Do you agree ?

Sam
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Re: Firing System : Help Needed

Post by Lloyd »

Sam,
The specs say its good operating all the way to 28VDC, so 24V looks just fine to me.

So far as power supply decoupling: Before you make too many choices, you need to define a few more things, like wire size for the power supply, distance of the power supply from the board, type of battery (some have higher internal resistance than other), connector types... and anything else you can think of that will affect the noise on the supply rail at the firing box.

One of the simplest decoupling schemes for distantly-powered devices is just a single blocking diode that allows current flow into the board, but not out, and a nice fat capacitor on the panel side of that diode that will charge up and carry the panel through short dips in the outside-world supply voltage.

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Re: Firing System : Help Needed

Post by sambo »

Hi Lloyd,

i've looked at an extensive list of battery types and capacities, including electric bicycle batteries, motorbike batteries, LiPos etc. I've come back to the same simple idea and I see that the cobra system does the same : 9v PP3 batteries !. See this excerpt from their website ( you can also find the manual there ) :

"The 18M uses three 9v (PP3) batteries. One of the 9v batteries is used to power the system operations only. The other two 9v batteries are used to fire cues only. By separating the power sources, you can ensure that full power is always available to fire cues even if the system has been left on for a long time.

The 18M also has a power conserving sleep mode. When powering off the 18R or 18R2 remote, the 18M will automatically fall asleep and conserve power for up to 24 hours. This allows you to place and arm your modules into position hours before the show begins. Then, when turning on your 18R or 18R2 remote, the module wakes up and is ready to fire.

On average, customers replace the same single 9v operational battery every 5 shows. It is not uncommon for customers to use the same operational battery for 10-15+ shows. It is not required to replace the batteries for every show. In fact, the two 9v firing batteries can commonly last 20-30+ shows. "

so, I'm thinking of simply using 3 x PP3 batteries to give me a firing voltage of 27V. The internal resistance of those batteries each is around 1.5 ohms which isn't ideal but clearly they work for Cobra !

seems lighter, cheaper and more convenient and easier for people to source than lead-acid type batteries.

What do you think ?

Sam.
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Re: Firing System : Help Needed

Post by sambo »

To cheat even more, they have done all the calculations for me !

Max e-Match / Igniters
22 AWG / 0.644 mm thick

Wire Length | Max Series | Max Parallel
--------------------------------------
50ft . / 15m | 10 | 4
100ft. / 30m | 9 | 3
260ft. / 80m | 8 | 3
820ft./ 250m | 6 | 2

24 AWG / 0.511mm thick

Wire Length |Max Series | Max Parallel
-------------------------------------
50ft . / 15m | 6 | 3
100ft. / 30m | 5 | 2
260ft. / 80m | 4 | 2
820ft. / 250m | 3 | 1
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Re: Firing System : Help Needed

Post by Lloyd »

"...seems lighter, cheaper and more convenient and easier for people to source than lead-acid type batteries."

------------
Sam, I agree with all of their premises AND yours, except for the last clause of that above statement.

The circuitry might run nearly forever on one PP3-style 9V, but I would NEVER trust PP3 types to reliably deliver enough firing current.

I know what their 'specifications' are. I also know how wildly off-spec many consumer brands are, and even the 'name brands' like DuraCell can sometimes fail on the max-available-current part. Failures in the weldment of the inter-cell straps or corrosion between cells in those not welded can KILL that spec in a heartbeat.

Although that might be fine in a CD-player, it doesn't 'play' well on a scripted fireworks show.

I'd put a 9V 'transistor' battery in the control, but I'd fire on two 12V (small) lead-acids. There are some pretty small ones. It's not cheaper, but I think it's safer.

Alternatively, I'd go along with some sub-C sized NiCd cells. But unless you buy model airplane packs, you'd have to weld them up yourself, which is an additional issue. A couple of 9.6V NiCd packs would join-up easily with the right connectors, and would be both relatively inexpensive, and readily available.

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Re: Firing System : Help Needed

Post by sambo »

ok, well, I completely take your point, and I have to defer to your expertise yet again on this one. Seems odd, though, that what I would consider to be a big brand would be recommending 2 x PP3 batteries for their cues for an entire show. They claim 10 - 15 shows per. pair of batteries ! Surely they would want to either sell the unit with rechargeable batteries integral within it or recommend the most reliable option ? ! ? !
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Re: Firing System : Help Needed

Post by sambo »

I think this would be my cost vs spec compromise ( obviously I would need 2 of them ) :

http://www.ebay.co.uk/itm/131220177132

Datasheet is here :

https://www.batterymasters.co.uk/Produc ... 2-TECH.pdf
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Re: Firing System : Help Needed

Post by Boophoenix »

Sambo, it's just become shared knowledge not long ago the energizer industrial batteries vastly out preform any other in the 9v line up. I believe Scott did some testing himself and agreed to that information. Prior he only recommended Duracell and Energizer batteries for his system.

Depending on the power draw to run your system ya might consider how Scott set his up too. Very often I have to replace the P1 battery, but the P2 batteries are still in good shape.

I have it on good authority Lloyd has a Cobra remote and a module or two sitting in a corner somewhere. I doubt it's been powered up in a while and should probably have the batteries removed.
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Re: Firing System : Help Needed

Post by sambo »

Interesting Brad...

Lloyd, what do you make of that ( Brad's points ) - this one has seriously got my brain in a twist.

I have just ordered 2 of the 12v batteries above - trigger happy I know !
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Re: Firing System : Help Needed

Post by Lloyd »

sambo wrote:Interesting Brad...

Lloyd, what do you make of that ( Brad's points ) - this one has seriously got my brain in a twist.

I have just ordered 2 of the 12v batteries above - trigger happy I know !
--------------
Here's what I make of them:

1)I have it on good authority Lloyd has a Cobra remote and a module or two sitting in a corner somewhere. I doubt it's been powered up in a while and should probably have the batteries removed.

It HAS been powered up periodically (because I know the worth of that), and it HAS had the batteries removed, some time ago, actually! They're still 'in the box' with the unit, but not in the battery-holder, and with a label indicating the NECESSARY frequency of inspection. (I've made that mistake before, but I won't make it on THAT equipment! I do the same on my own stuff. <grin>)

2) If Bradley says a particular make and brand of battery is reliable, then I'd trust him. He shoots with them a lot.

A great deal depends upon the firing-wire length. If the unit is within 3M of the matches, I'd not have a problem with it, even with my previous 'cautions'. Further than that, you'd have to ask Bradley about their performance -- by actual brand and model.

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Re: Firing System : Help Needed

Post by sambo »

ok,

well I have the lead acid batteries on order now so I have it covered and that's the spec I'll work to. Wouldn't it be nice to have this up and running cheaper than a commercial system, more reliable and home built

;-)
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Re: Firing System : Help Needed

Post by Boophoenix »

I really enjoy my Cobra. I've had very few failures that weren't my own fault. I can only think of one I never did figure out what caused it. You may find this interesting I predominantly shoot Talons as I like the added safety in some of the things I set up to shoot.

I have shot dual Talons with 3m leads off of slats with a 25m cables without any trouble. I don't use Ematches unless I'm shootings fireballs normally and planning to try those with Talon which should work just as well.
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Re: Firing System : Help Needed

Post by sambo »

Brad I'm thinking of trying to be as versatile as possible on the firing circuit. Given I have FETS that can handle up to 28v and several amps of current I think I can be. I might try and rig a board that will allow selection of different firing voltages.

Sam.
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Re: Firing System : Help Needed

Post by sambo »

Just a quick update on this project. I'm up to my eyeballs in writing code for this at the moment, having fun and games trying to interface to my xbees which then need to wirelessly communicate with the remote modules and needing to extend the communications protocol to do so.

For this I will need to put together another board but hopefully will have something to "show" soon.

Here is a video of the first board cycling a binary count test.

<***warning it's nearly 16mb***>

http://www.pyrobin.com/files/IMG_1580.MOV
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Re: Firing System : Help Needed

Post by Boophoenix »

Very cool Sambo. While I'm not very versed in electronics the gifts of talent people show never seems to amaze me here.
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Re: Firing System : Help Needed

Post by sambo »

Thanks Boo, I've had some really great help here.
The key thing here is going to be how much the build cost for the boards turns out at. The software will cost nothing as it's just my time.

Still working at it ;-)
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Re: Firing System : Help Needed

Post by Pyro-Gear »

You have done well Sam, the PCB printing would be costly in small amounts, I use a Fire Tech system http://ftek.eu/ it is an incredible bit of kit, but it would be nice to have a Pyro-Gear system in the offering.
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Re: Firing System : Help Needed

Post by dave321 »

ken,

you have a firetek system :o

that's like WOW ! you lucky person.

what do you have, 48e, 48s or the other module with 2 slats on the side ?
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Re: Firing System : Help Needed

Post by Pyro-Gear »

It’s a 48s they don’t cost a lot Dave.
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Re: Firing System : Help Needed

Post by Boophoenix »

I've seen those in my searching around. Glad ya like it Ken. I do like the Pelican cases over the seahorse cases I feel the Pelicans offer a little better flame resistance.

Two major things that bother me one I can't review any pricing that always a huge turn off to me the other I won't watch the first video. That Dave annoys me so much I can't stand to watch his videos if it's like most of his the video it will be 3/4 him and a 1/4 the firing system.

I've been quite pleased with My Cobra. I just wish I could talk Scott into a capacitive discharge module, lol.

I may have to investigate this one a little more someday.
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Re: Firing System : Help Needed

Post by Locky Smith »

I have just donated my fireTek 48s system to a lucky member of this forum. I'm sure they will put it to better use than I ever have.
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Re: Firing System : Help Needed

Post by Boophoenix »

Boy that sounds like someone got a nice gift. The pyro generousity never seems to lack the opportunity to surprise me.
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Re: Firing System : Help Needed

Post by Pyro-Gear »

Locky Smith wrote:I have just donated my fireTek 48s system to a lucky member of this forum. I'm sure they will put it to better use than I ever have.
Going out the country Locky ? ;)
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Re: Firing System : Help Needed

Post by Locky Smith »

You guess correct Ken, trouble is they require another 115 modules to rent for August.
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Re: Firing System : Help Needed

Post by Pyro-Gear »

Good call, get in contact with FT or should I say let them, FT have a 24hr support team the system is stunning and so expandable.
I can see you will be getting a front row seat and more Pyro tuition you could imagine.
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Re: Firing System : Help Needed

Post by Boophoenix »

It seems that many of the firing systems have stellar reputations of support.

Even though Scott ( Cobra's owner ) fields the calls himself personally he has spoken to me on New Years when I clearly told him I wasn't shooting for another few days and was fine waiting a couple of days. Even before I met him personally. I have worked with him a personal shoot of his since which was a blast. Those firing system guys do it up big when they wanna impress.
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Re: Firing System : Help Needed

Post by sambo »

just another quick update. I'm in for another re-design. the 100K series resistors I was using to protect the Op-Amps of course limits the firing current to 0.1mA so it won't be firing much :oops:

Pete Hand has kindly offered to help me out and he has some serious expertise in PCB design so I'm likely to be going back to using FETs to protect the firing lines and I'll keep you posted.

On a positive note, I have all the wireless communication working and Windows Client in Java so I'm 70 - 80% there !

Sam.
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Re: Firing System : Help Needed

Post by Lloyd »

Aw... Sambo! Does this mean we're 'breaking up'? <sob!>

<grin>
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Re: Firing System : Help Needed

Post by richardh08 »

Way to go Sam! I'm really impressed with what you have accomplished so far.
Even when I'm wrong, I'm convincing.
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Re: Firing System : Help Needed

Post by sambo »

Lloyd wrote:Aw... Sambo! Does this mean we're 'breaking up'? <sob!>

<grin>
Lloyd
no, the love is still there ! And thank you Richard. In fact I'm victim of the old thinking too hard syndrome again, the resistors aren't in series so there must be another problem and i've found a short on my prototype but i don't know where yet.

Pete has steered me away from Eagle which has helped a lot. He has also introduced some other thoughts and concepts which I'm struggling to keep up with but i'm just about hanging in there. FYI Lloyd, he has switched out the op-amps to LM339 ( which I have knocking around ) as this means I can drop the Zeners as they handle up to 39V or so. He has also switched the FETs to P-channel which have lower on-resistance and there is a cost saving. I'm trying to put together a new schematic.

Sam.
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Re: Firing System : Help Needed

Post by sambo »

Apologies for the large file, but I am still prototyping - this is the original circuit with the Smart FETs. Will be a while before I have a professionally manufactured board but Im getting there. Warning ! The file is around 20mb :

http://www.pyrobin.com/files/IMG_1688.MOV
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Re: Firing System : Help Needed

Post by Pyro-Gear »

Keep up the good work Sam it’s looking good, is your intention to market the product at some point.
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Re: Firing System : Help Needed

Post by Boophoenix »

The combined skill, experience, and creativity here trips me out. It's amazing
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Re: Firing System : Help Needed

Post by Pyro-Gear »

Sure a lot of people will appreciate that comment Brad, it’s what we do, we just keep moving forward.
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Re: Firing System : Help Needed

Post by sambo »

Thanks guys. The encouragement helps. My intention was to offer this to the community. I'd be happy to donate it to the pyro-gear cause. Still have a long way to go with it though.

Sam.
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