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. Lots o' issues are filled with vaguely interestin' articles, shiver me timbers, me bucko, rocket related o' course, me bucko, 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. Well, blow me down! Ya scallywag! I read and reread t' article several times, shiver me timbers, me bucko, and even contemplated tryin' t' wire up me own. Ahoy! Well, blow me down! Schematics and even a board pattern be included. Well, blow me down! Well, arrr, blow me down! Unfortunately, I studied mechanical engineering, and electrical things are still somewhat intimidating. Aye aye! I considered tryin' to put one together for about 4, maybe 5 seconds. Arrr!

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. Aye aye! However, as it turns out, me bucko, thar's a significant vertical component t' t' magnetic field, arrr, which means that, 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. Arrr! 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, ya bilge rat, and even had assembled a few kits for construction! Sweet!

I read his postin' more carefully and hesitate. Begad! SMT? That's Surface mount, isn't it? Bummer. Arrr! Begad! Blimey! For those o' you who are unfamiliar, ya bilge rat, 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. Ahoy! Arrr! Blimey! I'm pretty handy with an exacto, but a solderin' iron? Forget it.

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

I hold t' components down with micro-clips, shiver me timbers, then lightly touch the solderin' iron t' t' joint. Begad! 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. Ya scallywag! Avast, me proud beauty! I just broke one o' t' capacitors. Avast, me proud beauty! Arrr! I tried t' use hemostats to hold t' component in place as I solder it. Ya scallywag! Well, arrr, blow me down! I should have stayed with t' micro clips. Blimey! Ahoy! Lookin' over t' schematic and t' magazine article carefully, shiver me timbers, I figure out that t' value o' this particular cap isn't important. Ya scallywag! I fish out a tiny capacitor from me junk box and solder it in place. Avast, shiver me timbers, me proud beauty!

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

It doesn't work.

What did I do?

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

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

I have since purchased another kit and assembled it. Arrr! Both sensors have been calibrated and tested, though I haven't had t' chance t' actually fly them. Ahoy! Begad! 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, me proud beauty! Blimey! Get them while they last! Blimey! T' finished sensor is small enough t' fit in BT5!! Blimey! This opens up a huge realm o' model rocket design. Blimey! Blimey! Arrr! Blimey! I have lots o' sketches already for FAR OUT rockets. Blimey! Blimey! Just you wait! Blimey!

Here are me tips:

1) Get a solderin' iron, arrr, 15-20 watts, shiver me timbers, with t' smallest tip you can find. Avast, me proud beauty!

2) Get some tweezers and a magnifyin' glass. Begad! These things are tiny. Work on a large clean table where you can find items easily if dropped. Avast! Arrr! If you have a room with a hard floor, ya bilge rat, it will be easier t' find anythin' if you drop it. Well, shiver me timbers, blow me down!

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

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

5) Be patient!