Rocketry recovery deployment timer

I've attached a foto (if it uploads!!) of a 2 channel G-Switch activated timer for deploying the recovery system of my high power rockets..

Fully programmable dual channel output
30Amp mosfet outputs to fire the charges..
Launch detect
16X2 LCD to show status of the timer.
Clumsy user detection prevents premature ejection charge firing.
Usable to about 4 minutes straight up at Mach 2... Dunno how high that is!!!

Uses a 16F676 pic.
coded using Proton Plus + Compiler

I'll put a zip of the PCB and HEX file up if anyone is interested..

Thanks for the photo.

What is the G switch? I presume it is an acceleration sensor. Are they easily obtainable?

Len,

the G-Switches are simply acceleration triggered switches, and are very easily available. They come in a range of different activation levels too..
The ones I use are produced by Assemtech, and every major component reseller seems to stock them. UK price is about £2.50 each..

I've attached another foto, if you look under the LCD, you can just make out the gold coloured G-Switch.

Pretty neat, looks like the Robin PCB I just had made. Do you have a schematic you can post?

Does it launch with the rocket or stay on the ground? If it stays on the ground what is the acceleration switch for?

William At MyBlueRoom said:

Does it launch with the rocket or stay on the ground? If it stays on the ground what is the acceleration switch for?

Click to expand...

I think you already answered your own question?.

It goes up with the rocket... And hopefully, back down under a parachute... Ballistic recovery has a tendency to bollox the electronics and airframe!!!!!

I don't have a schematic as such, it was all done as a direct pcb layout from scraps of paper, direct into Sprint.. The pcb layout does have the comp overlay. It's such a simple circuit, that it should be easy to follow what's going on from the overlay...
Took longer to get the code working right.... All done in Proton picbasic, over a couple of evenings..

I'll post a link to the zip soon...

I had a sort of related question - why does it have an LCD on it? I think I'd figure out a way to remove it for flight.

I thought it did, but isn't weight and size a problem? Why are you sending the LCD display up?

People tend to think that a light rocket will perform better than a heavier (note, not heavy) one.... Try throwing a feather and then try throwing a pea.... A pea will go further.. Most rockets NEED some extra weight in the nose, to keep the CG in front of the center of pressure.. The display goes up with the rest of the avionics because it is easier that way.. And I have immediate visual confirmation of the flight events.. My timer is used as a backup for the primary flight logging avionics.. Big rockets are expensive to lose... And that's why I also use an RF beacon to locate it on the ground... All designed, coded and built by me!!!

The LCD is a standard 16x2 parallel LED backlit display, used in 4 bit mode. I think I paid about £2.00 on ebay... (Futurlec do some great deals on LCD's too...)
But at the end of the day, there was nothing available on the market that did the job, so I built my own... And got a great deal of satisfaction doing it. OOOPS.. rambling on.. SORRY!