I designed a very simple power converter for the snow flake decoration. The snow flake boards require 3.3V, a voltage which is not commonly available in a household. Therefore the power converter takes 5V USB power and convert it into the required 3.3V.

There is no fancy circuit inside of this box, lazily I simple used a Traco Power TSR2-2433 DC/DC power converter. It is a single component containing everything required. No external components like capacitors or resistors needed.

All other components you can see in the photo, I just added to make it more interesting. It is a simple circuit with a photo transistor and MOSFET which turns on the LED in darkness.

The functional aspect of this power converter is minimal. Like the snow flake decoration, it is more a piece of art than anything else.

Case Design

I used this simple board to do another test of the link between Autodesk Eagle and Autodesk Fusion360. For very simple projects like this, it already worked ok – still there is room for improvements. I used the board from Eagle as base, exporting it into Fusion360. There I created the case around the board as shown in the next image.

The idea was to create a laser cut case from 4mm transparent acrylic glass which is fastened by the spacer which also hold the board.

After this design process, I copied the outlines of all required elements into a own sketch in Fusion360 and arranged them there in an efficient way to the laser cutter. From there I exported all lines into a DXF file.

The engravings I created using Adobe Illustrator. In this program I could optimise the typography and lines for the laser cutter. Again I exported this elements as DXF.

All the DXF files were imported into the software for the laser cutter and combined. I just manually added the engravings to the sides. There was anyway no simpler method, because I had to adjust the parameter for cutting and engraving and mark the different elements for the job.

This software also automatically optimises the paths and order for the job, inner elements are cut before outer elements.

Glowing in the Dark

After cutting the elements, I used an acrylic paint base and mixed it with luminescent pigments. I filled the engravings with this paint and removed all excess paint from the flat surface.

Using this technique, the engravings glow in the dark, which is a very nice effect. On the daylight, the paint does not look different from a regular engraving. It has the same surface and colour.

This case and power converter are completely over-designed, but it gives the project a nice finish. It was an interesting practice to test some features of Fusion360 and Eagle.

The snowflake project was a pleasant art project I enjoyed really much. With the help of a number of Boldport Club members, I could keep the costs for the boards relatively low by creating a number of kits, which increased the batch size. While there are no kits available for the public, all files are open-sourced and available on GitHub. The repository contains Gerber files for the boards, a bill of materials and a full-featured firmware. So everybody can create his own snowflake decoration.

If you have questions, miss some information or just have any feedback, feel free to add a comment below.

Have fun!

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3 thoughts on “Snowflake Power Converter”

ahollis says:

2018-09-17 at 12:08

That is friggin awesome.

druck says:

2019-12-18 at 11:01

Would a Raspberry Pi be able to supply enough current to power the stars from it’s 3.3V line? If so, maybe it would be possible to drive the data line from a GPIO pin, allowing the Pi to control the patterns?

1. Lucky Resistor says:
  
  2019-12-18 at 11:11
  
  The Pimoroni snowflakes require 5V power, and 5 will sum up to 350mA, which is probably too much to route over a Rapberry-Pi. On the other hand, the data line has 3.3V logic level, just controlling the snowflake boards should be possible from a GPIO pin. If you power the snowflake boards and the raspberry Pi from the same power supply, you just can connect the GPIO with the data-in and GND with GND of the boards.