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. This 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.

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