Tiny Talisman Warns Wearer About UV Exposure

UV sensing amulet

Given how important our Sun is, our ancestors can be forgiven for seeing it as a god. And even now that we know what it actually is and how it works, it’s not much of a reach to think that the Sun pours forth evil spirits that can visit disease and death on those who bask too long in its rays. So an amulet of protection against the evil UV rays is a totally reasonable project, right?

As is often the case with [mitxela]’s projects, especially the more bedazzled ones, this one is approximately equal parts electronics and fine metalworking. The bulk of the video below focuses on the metalwork, which is pretty fascinating stuff. The case for the amulet was made from brass and sized to fit a CR2032 coin cell. The back of the amulet is threaded to act as a battery cover, and some fancy lathe work was needed there. The case was also electroplated in gold to prevent tarnishing, and lends a nice look when paired up with the black solder mask of the PCB.

On the electronics side, [mitxela] took pains to keep battery drain as low as possible and to make the best use of the available space, choosing an ATtiny84 to support a TTP223 capacitive sensing chip and a VEML6075 UV sensor. The touch sensor allows the wearer to wake the amulet and cycles through UV modes, which [mitxela] learned were not exactly what the sensor datasheet said they were. This required a few software hacks, but in the end, the amulet does a decent job of reporting the UV index and looks fantastic while doing it.

14 thoughts on “Tiny Talisman Warns Wearer About UV Exposure

    1. given that the pentagram points upward that would indicate some kind of wicca, and while i doubt there is crack involved, i would not doubt some kind of burning herbs. if you could rotate the pcb 180 degrees then it would indicate some kind of satan worship, or perhaps an appreciation of METAL, in which case, anything goes, pipe wise.

      i tend to point my pentagrams to the left to confuse people and to obfuscate what kind of drugs i use. if this has any kind of occult meaning, i dont know (though the left hand usually represents some kind of evil, occultism is some kind of hodgepodge that you probibly need to invoke complex numbers to understand what direction to point your pentagram for a given situation).

  1. That parts that kill me are that not only is it not solar powered but you can’t even see the indicators in the sunlight! There are lots of displays that work with sunlight but LEDs aren’t one of them.

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