Radio Frequency Launch Controller (mods move if in wrong forum)

[ben]

I figured it would go here since it is scratchbuilt. I am wanting to build a launch controller that is radio control using a Linx RF module

www.linxtechnologies.com

I want it to be 12 volt and have a ignitor continuity test. I was wondering i anyone could help me with this. I know how to make a "normal" 12V launch controller with igniter test etc. but I didn't know about a RF one. all I need is a simple explination about hookup. other than that I am set! Leeme know if anyone has pics of one. I would like to use this at my clube so they will have a wireless HPR pad.

thanx, Ben

 

[m85476585]

Basically the receiver will trigger a relay when it receives the launch signal. The relay will supply 12V to the igniter. You probably want to use some pretty big relays (maybe in parallel) so it can fly any HPR flight. You might even need a series of relays if the receiver has low output power, for example if it can supply only 50mA you could have a relay with a trigger current of about 20mA turn on some big relays which might need up to 1A. The bigger relay(s) could them fire the igniter.

You might want to get permission from your club because there is some debate about whether a wireless controller is safe. You could add a safety override so people can disable it at the pad if they are paranoid. You might also want dual pads in case someone wants to fly a hybrid rocket.

 

[jderimig]

There are of things you have to worry about when using a basic TX/RX pair, but the most important is how to avoid accidental triggers.

I would recommend buying a basic inexpensive wireless module that has a rolling code security system.

Very inexpensive systems can be found here

www.hobbyengineering.com/SectionRF.html

I have built a four channel pad with the 4 channel UHF unit and works great. Range is about 200 feet with the included keyfob, could get even more if I elevated the receiver antenna.

Good luck!
jd

 

[ben]

I plan on "scratchbuilding" the circuit. I like the rolling code idea but I think this will be ok. There are only one (maybe 2) people that have L2 to fly Hybrids and the fild is H and I on good days capable. This launcher will be F,G,H launcher. I am using it with a Rail for the MPR and HPR rockets. I plna on having the actual reciever box about 10feet away with a safety/arm switch. So if a mishap hapens the person will be at least 10 feet away. and the only way to Arm the launcher is by going to the box on the pad and arming it with a switch. I also was reading about a thing with relays where you could trip the relays if you don't want to launch. if you disarm the launcher at the transmitter it automaticaly disarms the pad box. Lemme know if that is posible!

thanx, Ben

 

[sylvie369]

I would want to know for sure that there were no other RF devices in the area before I went to the pad. Just disabling the one transmitter doesn't really "safe" the system if there are other transmitting things around, right? That's why digital code systems are so much safer - it's not just a signal, but a particular coded signal that trips the relay. I'd look carefully into JD's advice.

 

[stevem]

Ben, please read this thread if you have not already.

This is a project that could potentially be very dangerous - especially at a club.

I built a wireless 12v launch system and i love it. I feel it is a very safe system but yet I would not be so brave as to use it at a club launch. If I hurt myself that's one thing, but if I hurt others, well that's a horrible thing to have to live with.

Please consider using a premade wireless receiver and transmitter that uses rolling codes and has redundant relays.

 

[ben]

after thinking about it I have decided to get a rolling code 2 channel instead of scrathbuild. It is safer that way. That is very true that hurting anyone but myself is hard to live with I will ask Tom (RSO/LCO) what he thinks about it. If all else fails I can use it by myself with my launcher bymyself.

thanx, Ben

 

[sylvie369]

Originally posted by ben
after thinking about it I have decided to get a rolling code 2 channel instead of scrathbuild. It is safer that way. That is very true that hurting anyone but myself is hard to live with I will ask Tom (RSO/LCO) what he thinks about it. If all else fails I can use it by myself with my launcher bymyself.

Yeah! Good decision.

Hurting yourself would be pretty hard to live with as well. I'm very happy to still have all of my body parts intact in my mid-40s.

While I'm on the soapbox, take good care of your hearing as well (no loud music in ear buds!).

 

[ben]

I don't have to worry about music. I don't listen to the music that you can get a beat from when all you have is a subwoofer I am to much of a chicken to do to any crazy stunts so I will have all my body parts unless rocketry kills me

thanx, Ben

 

[sylvie369]

Originally posted by ben
I don't have to worry about music. I don't listen to the music that you can get a beat from when all you have is a subwoofer I am to much of a chicken to do to any crazy stunts so I will have all my body parts unless rocketry kills me

Well, some crazy stunts are worth it (I've got some great pictures of myself pulling 3+ Gs in an aerobatic Grob 103 sailplane over Hawaii and climbing Mount St. Victoire in Provence, and great memories of Grateful Dead tours in the 80s). Don't be too chicken. Just make sure that if you hurt yourself, it was doing something worthwhile, not testing a homemade device that you could predicted in advance might have problems.

 

[by basher]

I use a two channel system with rolling code keys. The first press "arms" the system with a latching relay, then the second press fires, then safes, the system. 30+ launches. All good.

When I find the box it came in, I'll post the dealers name.

 

[stevem]

this is the one I use

it was inexpensive and very easy to set up. The transmitter can easily be taken apart. I soldered wires in parallel to the switches on the transmitter board and then connected them to the pushbuttons on my hand held controller.