Spooky UV Strobe Light

I just picked up a $9 strobe light from Spirit Halloween, thinking I could do some mischief with UV-reactive ink.

This project will show you how to mod your own lamp to use UV LEDs, for spooooky decorations!

...Why?

I've been playing with Noodler's Blue Ghost ink, which is practically invisible until you shine UV light on it. I love the idea of hiding messages in plain sight, and I've used it to do a couple of art sketches as well, for Inktober (see below).

I put the ink in a knockoff Lamy Safari fountain pen from Amazon, bought a pack of 100 UV LEDs, and modded a book light to hold two of the LEDs. It works OK, but I needed a bigger lamp.

Plus, strobes are spooky.

The Hack

I opened up the strobe light and found that it took 3 AA batteries in series – 4.5 volts total. My LEDs each take 3V, according to the packaging, so the lamp would only power about 1.5 diodes. Boo.

I cut the leads to the existing battery pack, and soldered them onto a 9V battery connector.

I also de-soldered the four existing LEDs from the lamp, and replaced them with three UV LEDs: 3 LEDs x 3V each = 9V from my battery.

The video also includes a little derailment where I tried to put in a switch to directly turn the UV LEDs on/off. It'll take a little more thought than I can do on a live video stream, so I'll probably follow up with that later.

The Results

Here are a couple of pieces I did with the previous setup (book light). In order for these to show up, I needed almost total darkness in the room. The new lamp allows for some ambient light as well, providing plenty of illumination to overpower the regular visible light.

Go ahead and doodle a bit, and post your results!

Have fun!