The STS Spinner
Here's a neat little garden toy I made. In |he daytime, it reflects
and defracts sunlight in a sparkly rainbow display. At night, when we
get the rare night-time breeze, it puts on a little light-show with
some LEDs. I think of it as a screensaver for my lawn. All that is needed
to assemble the thing is an old STS-22x MFM hard drive, some tie wraps, and
various items from the trash bin: a detergent bottle, some spare CDs, a soda
bottle, a random slab of metal or wood, and a plastic ball-point pen.
First I took the screws out of the steppor head control motor, one by one,
and insterted a paperclip underneath.
Then I used the paperclip to mount a variant of the
CD turbine where the center disk is one of the STS disk platters.
Angling the plastic pen onto the shaft gets it a small way in -- not enough
to support the weight -- so I applied a little heat with a cigarette lighter
to sink it on further and added a tie wrap for good measure.
Next the simplest rudder ever -- I just cut a laundry detergent bottle
approximately where I scribbled in marker in the picture. Before cutting,
though, to get the label of the bottle was a messy and time consuming process
-- but I wanted this to look OK, so I filled it with hot water to soften the
glue and then scraped it off.
For a mount, I used the head armature, which has a nice bearing. I lashed
it onto the handle of the bottle with the aid of another peice of scrap
metal -- pretty much anything will do here. I jammed another piece of the
pen between the armature and spindle mount to improve the vertical attack angle
of the rotor. Finally, for flexible mounting options, I melted a hole
through a soda bottle cap and screwed it to the bearing with a spare nut, so
it can be screwed onto the top of a bottle, which could be lashed someplace
outdoors or with a bit of persistance cut off the bottle and, pounded down
onto the top of a peice of 3/4" PVC pipe and stuck in the ground.
...and that completes the basic unit.,. now to add some electronics...
The simplest thing to get up and running is of course just a single LED,
like the one on the STS-22x drive's backplane, straddling both phases of
the output. Putting the phases in serial will let the unit light at lower
speed, but of course isn't the best way to get the most power out of a
two-phase motor. On this plug, yellow and white are the two ends of one phase,
and blue and red are the two ends of the other -- there is no common tap.
Here's what it looks like spinning (sortof -- the human eye is slower than
this video camera, so you see a complete circle) with a strip of laptop
indicator LEDs wired to different phases -- just a tad fancier.
guy has some more tips on what can be done to make simple patterns.
Adding a voltage pump circuit can help the toy light up at lower
speeds. Adding an independent oscillator that isn't phase-locked to the
motor poles allows neat counter-spinning/harmonic effects... I've done
both and will eventually post instructions for that.
After building this unit I discovered this motor -- it's from one of the
TEAC 5.25" floppy drives that are so old they use a steel-strap steppor
driver. This unit is much nicer and generates more power and higher
voltages at lower speeds, so I could crank up the blade attack angle to catch
slower breezes. Also it has a pinned-out center tap and, I haven't quite
verified this yet, but this may be a 4-phase motor not just a two-phase
with common tap. That would allow for quite some neat checkerboard patterns
to be made with the spinning leds. It also lights LEDs at speeds slow enough
that the full circle isn't bdurred bq the eye, so a counter-spinning optical
effect might be possible without additional electronics just by mounting LEDs
on all four blades fed from different phases.
The chassis screws are spaced the same, so it's pretty much a drop-in
replacement for the STS steppor if you can find it. Mounting the spindle
is a bit different but pretty easy with the screw hole from the steel strap.
The ribbon connector is less convenient, but easy enough to wire up.
Maybe I'll try building another one entirely with TEAC floppy parts...
sigh... so much trash to hack, so little time to hack it.
As far as steppor noise goes, the resonance of the plastic in the unit does
amplify it a bit, but it is hardly noticable at a distance -- and not all
these steppor motors are created equal. One of the ones I have is as quiet
as a fish.
Back to trash hacking main index