To make this very blunt, I've actually used the reed relay from an old "101 Circuit Experiments" kit from Radio Shack (I think that was the name of it) to do something very similar to this. A couple of those big 6V lantern batteries can drive all sorts of stuff, managed safely by a relay.
Loki, I'm well aware that there's not enough juice from the LPT port to trigger the igniters, which is why I was suggesting a simple reed relay.
Here's the deal... A reed relay (which is common as dirt, literally-) has four (sometimes six) poles. The first two, which are your control, drive a little electromagnet (or solenoid--and the 5V from the LPT should be enough) which pulls a tiny metal arm (or sometimes a small ball of mercury) up against a pair of contacts, closing the circuit on the second set of poles. The six-pole relays just have two set of poles--one that's normally closed, and one that's normally open. So basically, you run a small amount of current through the control, and it closes the switch that allows you to have a larger amount of current running through the other side. Used this way, it can act like a transistor (with very high switching times, mind you) allowing you to control a "big" current with a "little" one.
lol no there is not enough juice to launch rockets just straight from an LPT port which I found out a while ago, however I only started this idea after I made a stop light and a music box using visual basic and turing programming languages to operate them. So I thought that I would be fun to have the ability to launch multiple rockets in sequence or a rocket with multiple engines, I know the ranges I have to stay out of for the safeties lol, but a smaller battery has solved my theoretical output problem according to my multimeter and express SCH lol but thanks for reminding me of relays I will use them on some other project later.
Actually, the 5V that comes off the pins of the LPT port should be enough to pull the reed switch closed, and you can run some pretty substantial current (by comparison) through the other side of it since it's electrically isolated. I wouldn't go crazy and try say, 110VAC through one without checking the specs on it first, but the 12-18VDC most people fire model rocket engines with should be cake. See http://en.wikipedia.org/wiki/Relay
Thanks for your help lol, I fixed my problem by using a smaller battery as an amplifier rather then the 9 volt battery that tripped my multimeter to lift off when the circuit was low.
You're an ignorant n00b and a coward. The amount of time you've been a member of Gaia doesn't change that.
By the way, please learn to read so that you can read forum rules and know why you don't post a bunch of HijackThis crap to get people to do your crapwork for you. If you could read, you'd also have known how to run the automated anti-virus removal tools listed in the forum sticky so that you wouldn't need to try to wrangle someone else into doing your crapwork, chumpcakes.
Vandalising this section with your comments isn't doing anything but showing everyone what a cowardly twit you are.
'Disabled my PMs, so this is the only way to thank you for that comment in my thread . I do appreciate l337-free criticism, though; so thanks.
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It's amazing to me that in this day and age that there are people stupid enough to think kidnapping and torture are perfectly normal parts of any sort of penetration testing procedure.
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