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, rocket related o' course, but t' one thin' that caught my eye immediately was 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. Ya scallywag! Avast, me proud beauty! Schematics and even a board pattern be included. Unfortunately, shiver me timbers, I studied mechanical engineering, and electrical things are still somewhat intimidating. Avast, me proud beauty! Avast! I considered tryin' to put one together for about 4, me hearties, maybe 5 seconds.

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, matey, me hearties, which means that, ya bilge rat, at least in certain parts o' t' world, me bucko, you can also have a "compass" tell you which way is magnetic "up."

KEWL!

Fast forward t' a few weeks later. Arrr! It's late at night and I'm pokin' through RMR when I see a postin' by none other than Robert Galejs himself! Blimey! 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! Blimey! Sweet! Blimey!

I read his postin' more carefully and hesitate. SMT? That's Surface mount, isn't it? Bummer. Blimey! Blimey! Begad! Blimey! For those o' you who are unfamiliar, shiver me timbers, me hearties, me bucko, 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, but a solderin' iron? Forget it.

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

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

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

Done. Arrr! Hook up t' battery. Well, blow me down! Blink. Arrr! Begad!

It doesn't work. Well, blow me down! Ahoy!

What did I do?

I look at t' components and double check t' instructions. Aye aye!

After much inspection and fiddling, arrr, matey, I decide t' send a note t' Rob and go to bed. Ya scallywag! Blimey! I get a response t' next day, and before I have a chance t' do the diagnostics he recommends, ya bilge rat, me bucko, I decide t' check t' solder joints again. Avast! Aye aye! This time I use an exacto knife. Avast, me proud beauty! Ya scallywag! Bingo! It turns out that 3 joints are nay complete. Ya scallywag! Avast! I solder them and it works!

I have since purchased another kit and assembled it. Ahoy! 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. Avast, me proud beauty!

I HIGHLY recommend this kit. 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. Well, blow me down! Just you wait!

Here are me tips:

1) Get a solderin' iron, 15-20 watts, with t' smallest tip you can find.

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

3) Use tape, me bucko, glue, me hearties, shiver me timbers, micro clips, arrr, etc. Begad! Avast, me hearties, me proud beauty! t' hold t' components in place while you're soldering. Avast! Be very careful about applyin' too much pressure as some of them are brittle. Ya scallywag! Avast!

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

5) Be patient!