Hacking a cheap disco light to fire UV beams.

Having modified a few of these cheap disco lights with other hand-made PCBs I decided to get a set of five prototype boards made.
Unlike the original light that pulses and flashes during operation, I decided to make it simple and just have a static pattern of light beams. That allows a very simple circuit to be used to power all the LEDs directly from the mains supply.

In this instance I decided to populate the PCB entirely with near-UV LEDs to project a series of deep violet beams of light through hazy air and create a grid of 64 points of light on a wall.
The really interesting bit is when you wear fluorescent items and walk in front of the light. It makes the material fluoresce as a series of dots on your clothing.

It's an unusual light. It would only be suited to specific events where a lot of suitably reactive colours were being worn. Like a rave or cyber party for instance.

I think the next one I make will have bright golden-white LEDs in it so it is a practical source of light with the advantage of being visually artistic too.
I'd also like to make one with the slow colour changing LEDs, but this application requires clear ones with the standard focussing lens on the front for highest efficiency. The RGB ones have the LEDs offset to the lens inside, so I'd expect to have to angle the whole PCB slightly to focus then through the main lens, and the light from each LED would be in the form of separate RGB beams.

Note that this particular PCB is better suited to higher voltage mains supplies like 220V upwards. For a 120V version it would require that the LEDs were in parallel pairs or two separate sections in parallel with either two power supplies or their own set of series resistors to help divide the current between the two sections. (Or a voltage doubler could be used to boost the voltage.)

The use of phosphor coated LEDs creates a softer beam effect than the laser-like effect of bare chip colours like red, green, amber and blue.

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