Here's some recent projects/happenings. For my new RC plane I needed reasonable charging facilities, because most trickle chargers like the one I got with the RC gear are trash. So after some thinking about building my own charge controller (not too tricky but time-consuming) I bit the bullet and bought this SJ Propo Swallow Advance charger: a very nice bit of equipment, charges pretty much anything from Lead-Acid to Li-Po intelligently, and with nice options. $90, so not exactly breaking the bank.

But the Swallow is DC only, 11-15V, good for taking with you in the car, bad for at home. I hate wallwarts. So I need: DC, preferrably 12V at 3-5A. But I have: loads of lousy underpowered wallwarts (bad) and loads of old garbage (good). Because the old garbage contains the innards of a few Sun SCSI enclosures, some of which came with brilliant fanless Sony-made switching PSUs. APS-28: old, silent, solid, juicy and saucy :-)

Time for the tinker: it simply took a few galvanised nails, some foam and a bit of soldering to convert the Molex outlets to posts for crocodile clamps. (There is extra insulation behind the foam, but the sparkies wouldn't be too happy with the design. Screw 'em!)

 2007_03_01-swallow-psu-bare.jpg  2007_03_01-swallow-psu.jpg

That PSU now also replaces three wallwarts, which makes me really happy. I fabricated some custom charging leads from scrap (old wires, some computer connectors, crocodile clamps from rotten test leads etc.) next: one 12V lead for the Yaesu VX5R which has its own charge controller (Li-Ion) and a tiny plug, one 12V fat plug for the CDMA phone's charger-stand (with its own controller).

The fat plug also works with the cordless drill, now and only after I gutted the drill charger stand: first I connected the Swallow to that, but the stand actually contains a few resistors for trickle charging. The Swallow blasted a few Amps at about 19V across that, the resistor got a tiny little bit hot, the stand plastic started growing surrealistic in shape and I quickly stopped things before the Magic Smoke got out. Now: gutless stand, brains in the charger. Me happy.

Another recent successful tinkerproject was modding Guntis' radio: he wanted a remote PTT switch to connect to his small speaker-mike sitting on his shoulder, just like the setup I've used for the last two years. (My new in-helmet setup was tested on Sunday and works superbly.) So I hunted up parts, traced the wiring in his speakermike and Simply Dit It. First I rewired the speakermike to activate on the PTT switch, and then I built a new remote PTT switch from scratch.

Here's the switch I made for him: 100% recycled components! :-)

 2007_02_25-guntis-ptt-side.jpg  2007_02_25-guntis-ptt.jpg

The switch is a leftover from a dead computer mouse that I desoldered, the cable with conveniently moulded-on mono plug comes from a first-crap-then-defunct $50 "stereo system", the button (for improved tactile feedback with gloves) is from the sewing kit my great-aunt left me, and the velcro was a leftover from some other project. Even the idea for the switch is recycled: this guy had it first :-) (Ok, solder, superglue and shrinktube were new. Sue me.)

And the next projects are already on the horizon: exploring the wonderful world of PIC microcontrollers. These things are cool! (I recently spent about $250 on a better multimeter and a bunch of chips, and may soon spend another up-to-$800 on an oscilloscope. Learning electronics is fun, but getting a reasonable set of tools is not -- for a money-concious person like me.)

Here's my first pic circuit: it toggles the led state on every switch activation, debounced in software. Looks like nothing, better stuff to follow soon because I've got shitloads of wacky ideas that I want to implement...

[ published on Thu 01.03.2007 22:21 | filed in interests/tinkering | ]
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© Alexander Zangerl