A persistence of vision planetary map, showing the angular positions of the 8 major celestial bodies

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Astrarium is a persistence of vision planetary map, showing the angular positions of the 8 major celestial bodies (sorry Pluto!) on any given date between 1800 and 2050.

Using a segmented mask, Astrarium does away with the complexity associated with rotating arrays of LEDs and is capable of displaying a variety of graphics including analogue clock hands and the phases of the moon. Running at 5400rpm, Astrarium makes use of 3D printed optical baffles, concentric diffusers and an ARM Cortex-M0 processor to achieve a resolution of 8x360 pixels at 25 frames per second.

There's an old hard-disk which I stripped down so that the front only has spindle coming through. I used a mill to face off some of the protuberances and other features which held the read/write head-arm in place. 

At the bottom there is a PCB I designed which is basically a carrier board, an I2C OLED screen fits on to that as well as the LPCXpresso 1114 board There are some buttons and a little slider pot for changing dates and speeds and so on. This PCB also has an array of FETs on it (to drive the LEDs) and some power management stuff (5V and 3.3V from 12V).

This board is connected directly with wires (urgh!) to the LED board. A round PCB which is home to 8 rings of 5 SMT LEDs. The LED board fits around the HDD motor spindle and is held in place with a few dabs of silicone - it's secure but I could get it off again if I had to.

On top of that PCB there are some diffusers and baffles to get the light to go where I want, they were 3D printed by Shapeways. The diffusers have little recesses in them so they snap over the LEDs on the board. The baffles then friction fit between them.

The HDD platter has been replaced with a circle of 1mm black plastic. The black disk has 8 holes cut in it, positioned so they sit above the diffuser rings. The plastic disk was CNC'd by a friend of mine and its held in place using the same screw cap and clamping rings which would hold the regular platter in place.

So the holes in the platter rotate above the illuminated rings at a known speed - I've got the LEDs connected to the LPCXpresso board so they sit across one byte of a hardware I/O port. In software, each rotation of the disk is split in to 360 1-degree slices. If I update the LEDs quick enough then single spots appear on the face of the display as all you see is a flash of light from that ring through the mask.

  • 1 × Osram SFH9201 Reflective IR sensor
  • 3 × Case C, 10uF, polarised, tant, capacitor Regulator holdup caps
  • 40 × Vishay VLMW11R2S2-5K8L-08 0603, White, SMT, LED
  • 1 × 0603, 47R, resistor Reflective IR sensor support component
  • 1 × 0603, 280R, resistor Reflective IR sensor current limiter

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  • Measuring the disk speed

    Dev Joshi02/22/2014 at 13:46 0 comments

    ​Currently, the disk speed is measured (somewhat unreliably) using an opto reflector mounted behind the platter. Once the 'scope in the office is working, I will have a poke around on the HDD control PCB on the back to find the timing signal which the motor controller uses to control/measure the speed. It should be relatively straightforward to patch it over to a free I/O pin on the LPC and get some better timing data in to slice the frames up. 

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JACOB wrote 10/16/2019 at 09:14 point

amazing! i want to make one

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Adam Gulyas wrote 08/20/2014 at 05:29 point
Skulled for the very cool video. (

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Herlander wrote 08/06/2014 at 09:36 point
Will you share a diy tut? I loved the concept and want one!! :D

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jeff.ballard.86 wrote 06/04/2014 at 01:17 point
It would be neat if it showed Pluto for the years it was a planet, along with any others that may not have been discovered during your time frame. Pluto is still a planet in my book :D

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Mike Szczys wrote 04/09/2014 at 14:22 point
I liked seeing it when we featured this on the front page:

But I absolutely love getting all the gory build details. Thanks for posting about your work!

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Thomas wrote 03/21/2014 at 02:55 point
Sounds very interesting, would very much like to see a video :)

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