Also would be nice to have a launch timer. Press the button and a countdown starts.

Thanks

For the box to launch prematurely, you have to have TWO failing components: The relay AND the first safety switch. So there’s no single point of failure.

Also, I think you guys should keep things in perspective: This box is meant for model rockets. What if water gets into your “Estes” ignition trigger and shorts the contacts? What if you drop that “Aerotech” launch box, it falls apart (which it does quite easily) and the right pieces of metal come together? There’s definitely an end to what you can prevent. The idea is to not have a single point of failure, i.e. don’t rely solely on a relay, don’t rely entirely on software, always require at least two different actions to be taken for a launch to happen (i.e. not just one single pushbutton)

I know this would never happen but i was just wondering, is there any safety device in place in case the device did develop a fault? I mean if for example water got in the unit and shorted the relay contacts making it activate?

I’ve posted the sourcecode, along with answers to your questions, here: http://www.playspoon.com/forum/index.php?topic=33

Could you possibly add some extra info?
- post the software
- list the sources/part #s for the switches, covers, and button
- what were the considerations in picking the PLED? Was it easy to use?

Harnessing the power of the internet, does any other reader have a reliable source for PLED displays? Do they all take a lot of power? I need a day-time readable output.

Thanks for the great write-up. Slick project!

Keys as mentioned above are a great idea, but like modern cars, don’t forget to add some kind of passive RFID system (different from the one from TI that was cracked a few years ago).

And one more thing – a local destruct mechanism to punish those who misuse the device. Poison gas, perhaps; we don’t want to harm the device.

Quote from http://www.osddisplays.com/pled.php

“Recently several of the world’s largest PLED panel manufacturers have announced their withdrawal from PLED production because of financial reasons. The withdrawal of these suppliers will have a direct effect on the availability of critical components that sustain OSD’s PLED module production.”

Quote from http://www.lcdforums.com/forums/viewtopic.php?p=17963

“Due to our PLED (Polymeric Light Emitting Diode) supplier announcing that they are no longer going
to be manufacturing this technology, we, Matrix Orbital, hereby submit this letter to inform you that we
must discontinue all of our products that use PLED technology.
…
Please note that PLED technology will be discontinued throughout the entire industry. It does not only
affect Matrix Orbital.”

If you have any links to places where I can get monochrome PLED (not OLED) character and/or graphical displays, please do post them!

I can buy them from several places. how the hell is something that is readily available rare?

I have some rare ardunio kits I’d like to sell for top dollar!

Switch 1 removes all power from the device. It is a safety switch that you will have a hard time toggling by accident – and even if you can do that, you still have to have a software failure and/or a problem with the relay *at the same time*.

So really, I see no problem there. Of course you could use a second port of the controller to switch a second relay. But the most important safety feature is the ability to physically remove power and thus override any individual software or relay problem.

As it is now, you should only enable switch 1 if you are ready to launch, just as you disable the safety of a gun only when you’re about to fire.