UV Exposure Box

Posted on December 7th, 2010

The front of my UV Exposure Box

I’ve redone this website and I’m going to re-post all of my old projects, starting with this one, the UV Exposure Box.

A UV Exposure Box is a critical component in creating your own PCB’s. You can find a good description of the process of manufacturing your own PCB’s here. For this item I’ll just say that at one point, when you’re using a process based on chemical etching, you are going to need to imprint your circuit design on your board. That’s where I use this UV Exposure Box.

I started out with the body of an old Trust scanner, I took out it’s guts and replaced them with fluorescent lights that emit in the UV spectrum.

Inside the UV Exposire BoxI got the actual lights and their fittings by buying a cheap second hand face tanner. Which was a good thing because when I tried to look for replacement lights I found they were not that easy to come by.

Next thing is the controller. A good UV Exposure Box needs a controller to keep the time. This way you can continue working on other things and the expose box will turn off the lights and give a buzz when it’s done.

Since I did not have an expose box at hand when working on the controller it’s still on perfboard.

UV Exposure Box ControllerThe board contains a big relay to switch the lights on and off, a small buzzer to make a sound when it’s time and connectors to the lights, the ICP and the LCD and the control buttons.

Here’s the schematic, click on it for full size:

The whole thing is controlled by an Atmel AT2313 microprocessor. This processor has 2Kb of flash ROM and since I insisted on programming this thing in c++ I used up every last byte of it.

The code is very straight forward. Thanks to the capacitors on the board there’s no need for additional ‘debouncing’ code which saves a couple of bytes which I used for a hidden bitmap.

Here are some more pictures of the finished exposure box:

UV Exposure Box Sourcecode