21 replies to this topic

[dr thrust]

thank you! just bought some from that ebay store , now got to wait for it to plop through the letter box! ps whats the poly stuff for?

[Asteroid]

It's mouldable plastic which melts at 60C and then solidifies again around 45C. Not so useful in pyro that I can think of, but great for whatever use you can imagine for it. Ergonomic handles are a good one

[dr thrust]

great for whatever use you can imagine for it. Ergonomic handles are a good one
[/quote]
fork handles?

[MFX]

Ah polymorph, excelent stuff for making low temperature molds, jigs for holding small/awkwardly shaped parts etc. but don't leave a lump of it on a car carpet on a hot day, you'll spend ages seperating it from the carpet fibres , particularly if it's set hard again

[Arthur Brown]

Remember that the camera flash will produce about 350 volts Cat5 cable is not spec'd for this and will break over - dumping all the power that should go to the igniter.

If you really need the 350v then the cable must be adequate, and you must be certain that the switches etc on the control box are OK at 350VDC

Proper professional HV firers have a safety circuit to stop them being fired into a high resistance ( >200 ohms) so that you cannot fire it into a person.

A device using a couple of PP3 batteries and a DC-DC converter can operate at around 48v and have a capacitor to discharge through the igniter. Or you could get a stack of AA or better batteries adding up to 48v.

Rocket igniters, esp DIY ones need more power than commercial pyro igniters, Le Maitre igniters are 20mA no fire and 500mA all fire so all you have to do is drive half an amp for a few milliseconds. This igniter is about 1 ohm so all you have to do is calculate the volts drop along your control wire at half an amp and supply a bit more.

[YT2095]

and it Might be an idea to have a Double switch and an Indicator, else you risk doing what a mate of mine did with a similar set up, and fused his Push-to-make switch shut and there was still power in the wire, when he went to check the post ignition ematch, he got a pisser off it!

2 switches in series is all you`ll need, so if you fuse the One, the other will break as it had already made a positive contact without a High voltage across it.


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[dr thrust]

sound advice, the caps always seem to have a bit left in them after firing i also was fuseing switches together but have got over this with a thinner nichrome wire and a small 12v relay,but i dont know if its worth all the trouble sometimes it works,sometimes not, works about 80% i would say.

[/right]

[right]

[ri also you have to wait for the damm thing to recharge,ok if your firing one rocket,no good if you have ten people watching you small back garden display