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RF controller for remote ignition

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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RF controller for remote ignition

Unread postAuthor: MrCrowley » Mon Nov 26, 2012 7:39 pm

For those of you that are familiar with my remote ignition circuit that I used on my piston hybrid, you know it uses a doorbell circuit and relay to switch the stungun ignition on and off. The first circuit worked great but I decided to replace it after I possibly destroyed one of its transistors when soldering one of the wires back on after it fell off. Since then I've been through 2 or 3 other doorbell circuits (got them for free) which were the updated version of the original circuit. These never seemed to work as well as the first one and after awhile they eventually stopped working all together.

I believe POLAND_SPUD and a few others suggested I should've used a cheap RF circuit with an in-built controller for switching 12V instead of a doorbell circuit. Now that my trusted doorbell circuit is out of production and replaced by some piece of crap, I decided to buy one of these.

I've known about them for awhile as I've been tempted to use them to control LED circuits (which they are designed to do) but I never got around to actually buying one. I bought mine from deal extreme as I've used that site before and they have free shipping but they might be cheaper on eBay for some of you (plus, shipping is slow on DE; took almost a month to get here from the day I placed the order).

Anyway, it arrived in the mail today. It wouldn't work on only a 9V battery so I beefed it up to 14V (was easier then trying to get exactly 12V) and it worked great controlling a 12v computer fan. The dimming function would also control the fan speed. I could trigger it from at least 30m away, behind fences, or behind cars. I haven't yet tried it out on the stungun yet. There's still a risk that the stungun could short circuit and find its way to the 12v controller so I need to think of some good ways to insulate the stungun. Currently, my ignition circuit will short circuit when attached to the hybrid cannon if the electrodes are held too far apart; the spark jumps from the stungun circuit, through the bottom of its project box, to the cannon chamber, to the metal hose clamp, and from there either to my hand on the toggle switches or through the toggle switches and in to the main project box housing the batteries and other circuits. I've placed big chunks of rubber surrounding most of the stungun circuit but it simply sparks through any gap in the rubber (where the rubber meets the project box or another piece of rubber). Think I'll have to make a little rubber enclosure for it :D

TL;DR - If you want a cheap remote ignition circuit, buy one like this. All you need to do is wire your 12V batteries to one side and the stungun to the other.

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Unread postAuthor: saefroch » Mon Nov 26, 2012 7:45 pm

Just a note, if you have or can make ceramic feedthroughs, they will work better than rubber.

I think I'll be investing in one of these, great idea! Love to see a demo video :wink:
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Unread postAuthor: jackssmirkingrevenge » Tue Nov 27, 2012 2:07 am

Potential for accidental firing from external interference?
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Unread postAuthor: MrCrowley » Tue Nov 27, 2012 2:16 am

Probably more so than the doorbell, don't remember seeing any switches to change the frequency code or whatever. Think I'll be alright though, I shouldn't be close enough to any interfering devices when shooting these days.
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Unread postAuthor: MrCrowley » Wed Nov 28, 2012 5:25 pm

Actually, there is one problem I forgot to mention. I'm pretty sure this controller circuit has memory so that when it is next turned on (i.e. connected to a battery), it remembers what dim setting it was on and whether the circuit was opened or closed. If the circuit was disconnected from the batteries when it was in the 'closed' position (letting the 12V power the load/stungun), I think that when it is connected again it will resume as if the circuit is closed. If I'm about to fire the cannon and flick the toggle switch that disconnects/connects the battery from the RF controller, I could end up firing the cannon when I'm next to it if the circuit is already in the closed position.

Not sure how I can get around this problem :?

edit: it's worse than I first suspected, by default it switches to the closed position when the batteries are disconnected and then reconnected. I could move my toggle switch from between the 12V battery and the controller to the output of the controller and stungun but I think that might use up battery whilst idle. Instead, I could move the toggle to the latter position and put another switch between the battery and controller input. When I turn this switch on, I have to make sure the repositioned toggle switch is in the open position so no spark will go to the chamber. I then have to press a button on the remote to switch the controller to open, then switch the toggle to close and then get in to position to fire the cannon via the remote.
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Unread postAuthor: jrrdw » Thu Nov 29, 2012 5:31 am

You should buy a 15 dollar cell phone and keep the number to yourself. Don't hook it up until it's been turned on for at least 2 minutes to clear any add minutes messages. Then just text "FIRE" to your cannon to fire it.

I think that would be less trouble then the RF unit your working with now. Less outside interference as well.
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Unread postAuthor: POLAND_SPUD » Thu Nov 29, 2012 8:32 am

You should buy a 15 dollar cell phone and keep the number to yourself. Don't hook it up until it's been turned on for at least 2 minutes to clear any add minutes messages. Then just text "FIRE" to your cannon to fire it.

I think that would be less trouble then the RF unit your working with now. Less outside interference as well.
even when I got a prepaid SIM card I got a bunch of calls and texts from companies trying to sell me some sh## - no idea how they got my number - I assume one could select them at random

since anyone can call that number the gun can pretty much fire at any moment



You could use arduino board and AT commands to send and read texts - if you can find a phone that has TTL compatible serial pins (there are some but mostly older ones)
If you can get one you could have a remote ignition system that fires the gun only if the phone receives a text that contain a specific code (eg. 'fire' or 'ignite')


though if you have arduino you might as well spend 10$ and buy a bluetooth module - then use this one your phone >>
http://www.spudfiles.com/forums/fueling ... 24760.html
:D
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Unread postAuthor: dewey-1 » Thu Nov 29, 2012 11:34 am

This one has better control than the "dimmer" type.
Think of a garage door opener remote system. You only toggle the remote once.

http://dx.com/p/wireless-remote-control ... 12v-126958

The LED dimmer type is not what you need. It has a "latched" on condition so you control brightess. You need to toggle the remote two times for "On-Off".

You want a "momentary" On function for your application. This what the doorbell type remotes use, it is "momentary" for the melody duration.

Here is a good explanation of momentary, toggle, and latched.
Sometimes called M,L,T format as mentiones in DX remotes.

http://www.ebay.com/itm/1CH-9V-12V-24V- ... 337a67aa8b


Here is manual link and custom ordering.

http://www.carymart.com/index.php?main_ ... ts_id=1410
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Unread postAuthor: jrrdw » Fri Nov 30, 2012 7:42 am

POLAND_SPUD wrote:even when I got a prepaid SIM card I got a bunch of calls and texts from companies trying to sell me some sh## - no idea how they got my number - I assume one could select them at random


Funny, I've only ever gotten minute warnings from these things but anything is possible.

You could use arduino board and AT commands to send and read texts


That's the best idea. The sequence of events could be programmed to happen right down to the millisecond. Even build in fail safes like for something moving into the line of fire could cancel the event. Using a garage door lasers, if you want to go that far with it...
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Unread postAuthor: POLAND_SPUD » Fri Nov 30, 2012 10:43 am

Funny, I've only ever gotten minute warnings from these things but anything is possible.
AFAIK you've got some sort of list of ppl who don't want to get advertising calls and stuff so probably your situation is a bit better.

ohh found it -> http://www.fcc.gov/encyclopedia/do-not-call-list

Still I wouldn't feel safe knowing that the gun can fire virtually at any moment

The sequence of events could be programmed to happen right down to the millisecond

well maybe not miliseconds but certainly close to 1.5 second, note that the message has to be sent and then received and it doesn't happen instantly

But yeah it is easy - it goes down to sending this command through serial
AT+CMGL="REC UNREAD"



and the mobile returns through serial all of its unread (new) messages - plus some extra data like the number that sent it and date

for example
+CMGL: 1,"REC UNREAD","+85291234567",,"07/02/18,00:05:10+32"
acctual text of the text message.


So you just create an if statement in code that ignites the gun only if the message contains string 'FIRE'... or you might even check if it was sent from your number


lol though now that I think of it... what will the police do when they find a cell phone ignitor (OMG a terrorist)?
lol if you're unlucky you might be on the news
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Unread postAuthor: MrCrowley » Sat Dec 22, 2012 11:00 pm

Now with video:
[youtube]http://www.youtube.com/watch?v=H3OOTvjIBYw[/youtube]
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Unread postAuthor: MrCrowley » Tue Jan 08, 2013 11:30 pm

and a basic How-To guide:
[youtube]http://www.youtube.com/watch?v=3aVlZ58YTVQ[/youtube]
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Unread postAuthor: wyz2285 » Wed Jan 09, 2013 3:16 am

That's what I usei in my hybrid, a remote controled 12v relay.
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