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Old May 11, 2012, 10:59 PM
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Legot's Avatar
United States, AZ, Gilbert
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Originally Posted by Endlesslag View Post
I used a brushed ESC and the estes igniters to launch em,
I had a friend do that with some rockets and Jato a plane a couple years ago, the video's lost on youtube somewhere, but it worked the first time, and splintered the plane the second

It does get me thinking though, I'll see if I can do up a little something that can light something by an rx channel.
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Old May 11, 2012, 11:09 PM
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United States, KY, Paducah
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TP, how old are you?? If you're a senior, you're way younger than I had thought. I would've guessed mid-twenties or so. You're more like around my age I'm guessing (I'm 16).

I had seen on the Internet past night that you could use a brushed ESC to give power to an igniter. I thought this was a pretty cool idea. I'll be on the lookout for cheap brushed ESCs now. I wouldn't guess I would need anything bigger than a 10amp one. Whadaya think?
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Old May 11, 2012, 11:18 PM
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USA, VA, Spotsylvania
Joined Jan 2011
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Quote:
Originally Posted by PyroMan View Post
TP, how old are you?? If you're a senior, you're way younger than I had thought. I would've guessed mid-twenties or so. You're more like around my age I'm guessing (I'm 16).

I had seen on the Internet past night that you could use a brushed ESC to give power to an igniter. I thought this was a pretty cool idea. I'll be on the lookout for cheap brushed ESCs now. I wouldn't guess I would need anything bigger than a 10amp one. Whadaya think?
http://www.amainhobbies.com/product_...rce=google_ext

Should do the trick, HK has some but they're out of stock for right now.

Also...maybe there is hope for the future generation, there's quite a few more of us younger kids into RC than I thought. Unfortunately we're few and far between...Guess we have DARPA to thank for the internet, and therefore rcgroups
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Old May 11, 2012, 11:25 PM
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United States, AK, Fairbanks
Joined Aug 2009
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I'm 17. I should technically be a junior, but I decided that 8th grade wasn't really necessary so I'm a year ahead of myself

Those ignitors won't take much current at all. I just dug a couple out and fried 'em up with them hooked to my wattmeter. First one went too fast to get a reading, but the second hit a 0.15A measured peak at 7.57V input. Now my room smells like... death...

In short, a 10A ESC is plenty
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Old May 11, 2012, 11:29 PM
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Originally Posted by PyroMan View Post
TP, how old are you?? If you're a senior, you're way younger than I had thought. I would've guessed mid-twenties or so. You're more like around my age I'm guessing (I'm 16).

I had seen on the Internet past night that you could use a brushed ESC to give power to an igniter. I thought this was a pretty cool idea. I'll be on the lookout for cheap brushed ESCs now. I wouldn't guess I would need anything bigger than a 10amp one. Whadaya think?
Well to light one with a "general purpose" igniter, like for rockets, you would probably need 2.125 volts at 14.16 amps according to this.
http://www.gwiz-partners.com/igniters.pdf
Which would translate to somewhere around a maximum of 2.5 amps @ 12v, and like 6A @ 5v.

Note that those currents are only for like 3 or 4ms, so even a <1 amp ESC should handle it.

I'm right now I'm seeing about making a bare bones brushed ESC for use with this stuff, just to get it going for people who don't want to but esc's. If I'm capable of it, It will be designed by morning Especially now that I'm done with the Apush test.

So, a 10 amp brushed ESC is still overkill.
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Old May 11, 2012, 11:38 PM
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Keep Ohm's Law in mind... Increasing the voltage would just crank the current up even more (but the thing will burn a heck of a lot faster). I'd say you could probably get away with using servo guts for ignition purposes.

There are more attractive options. If you have an extra proportional channel (knob, slider etc.) you could do the math and get some resistors wired up in series with your ignitors, and then wire those all up in parallel with your ESC. Advancing the slider would slowly increase the voltage across your ignitor/resistor combos and you'd be able to control multiple independent ignitions off one channel. It might take some fooling to get it figured out, though.
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Old May 11, 2012, 11:47 PM
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That's clever, I was just thinking about using a non-proportional channel and using a small potentiometer to to set a delay on each charge by using an Attiny as a processor, I was also thinking about using discrete components, but It would be too heavy for what it needs to do.

A mcu would make it a whole lot easier to do the proportional channel idea too. Add a few transistors to either idea, hook it up to the flight pack, and those things would be going off perfectly.
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Old May 11, 2012, 11:51 PM
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Quote:
Originally Posted by C₄H₁₀ View Post
I'm 17. I should technically be a junior, but I decided that 8th grade wasn't really necessary so I'm a year ahead of myself

Those ignitors won't take much current at all. I just dug a couple out and fried 'em up with them hooked to my wattmeter. First one went too fast to get a reading, but the second hit a 0.15A measured peak at 7.57V input. Now my room smells like... death...

In short, a 10A ESC is plenty
Same here, I'm technically supposed to be a sophomore, but I skipped 6th or 7th grade (can't remember which one) so I'm ahead also.

Legot, that would be very handy if you could make your own brushed ESCs. I thought they would've been cheaper since everyone is pretty much going to brushless :rollseyes:
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Old May 11, 2012, 11:53 PM
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Originally Posted by Legot View Post
That's clever, I was just thinking about using a non-proportional channel and using a small potentiometer to to set a delay on each charge by using an Attiny as a processor, I was also thinking about using discrete components, but It would be too heavy for what it needs to do.

A mcu would make it a whole lot easier to do the proportional channel idea too. Add a few transistors to either idea, hook it up to the flight pack, and those things would be going off perfectly.
I don't know too, too much about electronics - so what's an mcu?
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Old May 11, 2012, 11:59 PM
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Originally Posted by PyroMan View Post
I don't know too, too much about electronics - so what's an mcu?
A MicroController Unit, if you've ever heard of arduino, it's the main chip on those things.

And since I think I'll go the mcu route, I'll be using arduino since it's easiest for me, and easiest for most people as well, lol.
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Old May 12, 2012, 12:15 AM
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Ohhh okay. Yeah.
I hope you figure this out so I can have my own for cheap. My older brother is really into electronics and is normally either routing a PCB on the computer, soldering, or programming his arduino so I think he'll be able to build me an ESC. . .
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Old May 12, 2012, 01:04 PM
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United States, IA, Coralville
Joined Jun 2011
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What if you used the flash charging circuit from a disposable camera, which charges up a capacitor to around 180V, and then use a transistor connected to your receiver to trigger it so it would light up the igniter? That would eliminate having to supply large amounts of current. Just an idea.


I find it amusing how launching fire from the sky is a topic that attracts almost exclusively us high-schoolers. I'm a Junior.
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Old May 12, 2012, 02:53 PM
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I'm pretty sure there are more than just high schoolers interested in it... How do you explain the MQ-1?
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Old May 12, 2012, 02:57 PM
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Originally Posted by C₄H₁₀ View Post
I'm pretty sure there are more than just high schoolers interested in it... How do you explain the MQ-1?
Isn't it obvious - they had highschoolers working for the governent.
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Old May 13, 2012, 12:21 AM
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Okay so I was playing around with a busted servo's guts for a switch of sorts for an igniter. Since the servo kinda acts like a brushed ESC, i think it could work quite well. I dont know if it would pull too many amps with just the servo so I was thinking i could use the servo to engage a relay with 9v and such. I only got to look at it for like half an hour, maybe I'll yet some time tomorrow. . .
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