Help finding components

There are a number of companies that make these, such as Panasonic (Japan), MaxFarad (Korea), ELNA, Nichicon and NuinTCK (Korea). They are commonly called Double layer electrolytic capacitors, Super Capacitors or Ultracapacitors (depending on type and brand). I dont know what country you are in so I cannot suggest which local distributors might supply thes brands. Most have a working voltage of

You don't mention the voltage rating or the peak current that you need to supply. I think what you need is a double layer or "supercap". They are available in a 22F, 2.5V rating. See the Digikey catalog, for example. If you need higher voltage, you may have to use a series-parallel combination to get the capacitance/voltage combination that you need. You also may have to connect some equalizing resistors in parallel with each series cap. Regards, Jon

thanks for your help

Looking at how expensive they are, a series configuration is not an option.

I need a lot of charge and a peak voltage of 200 VDC at the output of the circuit. I think can i use a voltage multiplier (diode cascade) ladder, with the capacitor discharge through it. Will this work?

Thanks

Look at the igniters' specs. What's the minimum current you need to put through them to make sure they fire reliably, and for how long? What's their resistance like; what's the minimum voltage you need to sustain across them during the above period?

There's a reason most folks ignite rockets with batteries rather than capacitors, whether ordinary, super, or ultra.

Mark L. Fergerson

What? What are the capacitors for? People have been doing this for decades, with no need for such an exotic part.

Besides which, for firework ignitors, I wouldn't trust any purely electronic solution, especally at what sounds like your level of expertise. I'd go for something like a gearmotor driving a switch array with a cam, or driving some kind of rotary switch itself.

Well, OK, there _are_ ways of doing it electronically that could be made reliable, but how much time do you have to spend learning how to do it?

Good Luck! Rich

On Mon, 13 Feb 2006 19:18:22 +0000, thorin92 top-posted:

What the hell do you need 200V for? You can fire squibs with a 6V lantern battery!

Go lurk news:rec.pyrotechnics for awhile - something will show up.

Good Luck! Rich

Do you mean for their stored charge ?

The large 'super caps' that are available aren't made for rapid discharge. Maybe you should reconsider your approach.

Graham

A person using a nail board and a watch with a second hand (or counting intervals "one thousand-one, one thousand-two, one thousand-three...") should be able to ignite 15 pieces of fireworks at one-second intervals!

Works great for me for small finales you want to shoot electrical and not to bring all the equipment.

pyrohobie

While capacitive disccharge firing boxes are today widely used in both commercial blasting and fireworks, the construction and safe use of one is far beyond the capabilities of someone believing that they need "ten

To echo Mike's post, what this poster needs is a "nail board", sopmething simple to construct and easy to understand.

Over the years, I've constructed roughly 15 simple BC (battery/capacitor) firing systems (none of which involved electronics) using capacitors ranging from 20 to 50 MFD charged by battery to voltages between 67.5 through 180 volts. All functioned as intended.

Just for the record, I've never seen even a 1 Farad capacitor rated at over a few volts, which suggest to me a lack of electrical know-how on the part of the original poster.

I would suggest that the most basic method for discharging 15 fireworks spaced one second apart would be to connect them together with 1-second of fast Visco, pleated quickmatch, or 1-second timing fuse between them. Beyond that, a nail board is likely a simple solution.

Harry C.

Rich Grise wrote:

Here is a simple model rocket launch sequencer using 555 chips and a single trigger to launch standard igniter based rockets at preset intervals. Scaleable to as many rockets as you need.

Just power of a 12V car (or similar) battery. No 20F caps at 200VDC? required (and A LOT simpler).

If you take apart one of those 'fluorescent low energy mini lightbulbs' you'll find 15-20uFd 200V electrolytic caps among other components. you can get these bulbs cheap now under $3.00 and there's 20bucks worth of parts.

Yabbut, he'd need at least ten million of them to get his required capacitance.

Best regards, Spehro Pefhany

Capacitors definitly come around these ratings! Most car audiophiles use these on their 12vdc systems , most in the 1-2 farad range! But no to get a little spark you definitly wouldn't need something this large!

As well 'Power factor correction systems' (Research it on the web to long to explain) uses high voltage capacitors at very high ratings as well !

Rob

Precisely. They are not capacitors in the conventional sense of the term, more closely approximating a storage battery.

Turning to firing system basics, the amount of energy stored in a capacitor is given:

Q = 1/2 CV^2 Where:

Q = Stored energy in Joules C = Capacitance in Farads V = Charged potential in Volts

Since the stored energy is proportional to the square of the voltage but only directly with capacitance, the design of capacitive discharge firing sytems are generally optimized when relatively small capacitors charged to high voltages are employed.

An added benefit of this approach is that it minimizes the effects of firing cable resistance through the use of high firing voltages, in turn allowing longer runs of smaller gauge cable.

This is why so many pyros have converted the flash circuity in disposable cameras to serve this function.

Harry C.

One step above the disosable camera system is Honeywell photo flash units. Many have a 2 second recharge so with a little visco, you can have 1 second ignition. 1000 V spike very quickly tapers to 380 V. Yes you can fry your self. In one setup, I attached brass wipers with detents to the underside of the flash unit. These wipers contact pairs of rivets on peg board framed with 2x2 stock. 42 cues with ten igniters possible per cue. If you don't share grounds, this system can not back feed so you do not need diodes. Just add a fire button, and wipers. On/off switch, charge indicator are already built in! There is a quick recharge self defence stun zapper that looks promissing for long chains. While not very sexy, this system works every time and cost squat. I bought a like new thyristor model still in the box for $10.

hmmm...... a 20 farad cap would be the size of a tall building, He most likely meant 20ufd.