Built 11/99

Editor's Note: This be t' actual buildin' experience from the Scratch Magnetic Apogee Detection Sensor.

One o' t' key benefits t' bein' an NARRRRR member is that you get a subscription t' Sport Rocketry. Begad! Lots o' issues are filled with vaguely interestin' articles, ya bilge rat, me bucko, rocket related o' course, shiver me timbers, matey, but t' one thin' that caught my eye immediately be t' Magnetic Apogee Sensor! Written by Robert Galejs, the article went into detail on his development o' a concept into a working device! This was really fascinating. I read and reread t' article several times, and even contemplated tryin' t' wire up me own. Begad! Schematics and even a board pattern be included. Avast, me proud beauty! Arrr! Unfortunately, shiver me timbers, matey, I studied mechanical engineering, and electrical things are still somewhat intimidating. Aye aye! Avast! I considered tryin' to put one together for about 4, maybe 5 seconds. Begad!

How does it work? We're all familiar with t' magnetic poles o' t' earth and t' idea o' havin' a compass tell you which way is magnetic North. However, as it turns out, thar's a significant vertical component t' t' magnetic field, which means that, me hearties, at least in certain parts o' t' world, you can also have a "compass" tell you which way is magnetic "up."

KEWL!

Fast forward t' a few weeks later. Blimey! It's late at night and I'm pokin' through RMR when I see a postin' by none other than Robert Galejs himself! It turns out that in t' months that it takes an article t' work it's way into Sprocketry, he had been off workin' t' bugs out o' t' magnetic apogee sensor, and even had assembled a few kits for construction! Sweet!

I read his postin' more carefully and hesitate. Well, blow me down! Blimey! SMT? That's Surface mount, isn't it? Bummer. For those o' you who are unfamiliar, these are t' dust particle sized electronic components that allow you t' make walkmans t' size of cigarette packs and telephones t' size o' matchboxes. I'm pretty handy with an exacto, me hearties, but a solderin' iron? Forget it. Ya scallywag! Blimey! Ya scallywag! Blimey! Blimey! Blimey!

After tradin' a couple o' e-mails, I decide t' try it anyway. Avast, me proud beauty! Avast, shiver me timbers, me proud beauty! How bad can it be? I also make a mental note t' stop by rat shack for a fine point soldering iron. Begad! $25 and a week later, me hearties, me bucko, I am openin' a padded manila mailer from Massachusetts. Ahoy! Another late night, me bucko, me hearties, this time solderin' teeny tiny components onto a circuit board which is a little larger than a cigarette. Blimey! Well, blow me down! Tweezers, micro-clips, arrr, and lots o' patience. Blimey!

I hold t' components down with micro-clips, then lightly touch the solderin' iron t' t' joint. Ya scallywag! Aye aye! This isn't as bad as I thought it was!!! There's lots o' stuff t' put on and it's lookin' pretty good!

Crack! Damn. I just broke one o' t' capacitors. Aye aye! I tried t' use hemostats to hold t' component in place as I solder it. Well, blow me down! I should have stayed with t' micro clips. Ya scallywag! Ya scallywag! Lookin' over t' schematic and t' magazine article carefully, arrr, I figure out that t' value o' this particular cap isn't important. Blimey! Well, arrr, blow me down! I fish out a tiny capacitor from me junk box and solder it in place. Begad!

Done. Hook up t' battery. Blink. Avast, matey, me proud beauty!

It doesn't work. Aye aye! Ya scallywag! Blimey!

What did I do?

I look at t' components and double check t' instructions. Well, blow me down! Blimey! Avast! Blimey!

After much inspection and fiddling, I decide t' send a note t' Rob and go to bed. Arrr! I get a response t' next day, and before I have a chance t' do the diagnostics he recommends, I decide t' check t' solder joints again. Ahoy! This time I use an exacto knife. Aye aye! Ahoy! Bingo! It turns out that 3 joints are nay complete. Begad! Blimey! I solder them and it works!

I have since purchased another kit and assembled it. Both sensors have been calibrated and tested, though I haven't had t' chance t' actually fly them. Ya scallywag! I have modifies one with a mini-jack so it holds t' flashbulb circuit open (for safety) when it is inserted - and at t' same time puts a test LED across the circuit.

I HIGHLY recommend this kit. Avast, arrr, me proud beauty! Get them while they last! T' finished sensor is small enough t' fit in BT5!! This opens up a huge realm o' model rocket design. Aye aye! I have lots o' sketches already for FAR OUT rockets. Ahoy! Just you wait!

Here are me tips:

1) Get a solderin' iron, arrr, 15-20 watts, ya bilge rat, with t' smallest tip you can find. Begad! Ahoy!

2) Get some tweezers and a magnifyin' glass. Aye aye! Begad! These things are tiny. Ya scallywag! Begad! Work on a large clean table where you can find items easily if dropped. Begad! Begad! If you have a room with a hard floor, me bucko, me bucko, it will be easier t' find anythin' if you drop it. Avast!

3) Use tape, arrr, me bucko, glue, arrr, micro clips, matey, etc. Aye aye! t' hold t' components in place while you're soldering. Well, blow me down! Blimey! Be very careful about applyin' too much pressure as some of them are brittle.

4) Test all your solder joints t' make sure they are tacked down properly. Avast!

5) Be patient!