UV exposure boxes sell for hundreds of euros from vendors such as RS electronics and Farnell when they can be built at home for approximately 70 euro. I used a plant pot to build mine because it was the only opaque container I could easily get my hands on.
Here is a picture of the parts needed. Note that there should be two ballasts and not one.
Looking at the below picture of a close up of one of the ballasts you will notice that the circuit diagram printed on it shows that it can power two lamps (2x15W) in series. I tried doing it this way but could not get the lamps to start. So I bought a second ballast and wired a ballast to each lamp and it worked fine. This could just be due to the brand of ballast or the types of lamps I have.
This wiring diagram from wikimedia is very useful. This wiring layout is used for both lamps.
For the housing, a mirror on the base will help even the light distribution and increased the amount of light from the lamps that actually reaches the pcb. Also on top of the box you will want piece of glass or clear acrylic to sit the pcb on. I got a piece of mirror and glass cut for 10 euro from a local glass cutting company. Here is a picture of the mirror sitting in the plant pot:
Next I added in the screwed the ballasts on the inside of the pot and made a hole for the mains connector which was just a three pin mains socket. From there just followed the wiring diagram above and ended up with this:
Plug in the mains after checking wiring to make sure everything works as expected:
Hiding the electronics is the next step. This is for two reasons. The first being that the electronics look fairly unsightly (Not that I’m going for aesthetics here or anything). Secondly, it is better if the section of glass left visible is lined up with the center of the two lamps. So when you put down a board it is easy to line it up in the middle of both lamps for even light distribution. I used electrical tape to cover up part of the glass like so:
I didn’t put a lid on the box because it really doesn’t seem necessary. I think just placing the board on the glass then maybe putting a piece of wood on top should do the job just fine. I didn’t add a timer either, I’m just going to use a smartphone timer app and manually turn off the power. Also, there is not switch because the power socket I use for this has a switch, or the cable could just be unplugged.
Bill of materials
Quantity | Part | Source | Price (Euros) |
|---|---|---|---|
| 2 | Magnetic Ballast 30W | RS electronics. Order No: 7934682 | 18 |
| 2 | T8 Fluorescent Lamp 10W | Ebay http://goo.gl/KAbd4J | 20 |
| 4 | 4 T8 Lamp holders/clips | Electrical wholesalers | 2 |
| 2 | Fluorescent Starters | Electrical wholesalers | 2 |
| 2 | Fluorescent starter holders | Electrical wholesalers | 2 |
| 1 | Mains power 3 pin socket | Electrical wholesalers | 1.50 |
| 1 | Single core wire (3 metres) | Electrical wholesalers | 2.50 |
| 1 | Piece of mirror (30cm x 20xm) | Glass supplier and cutter | 5 |
| 1 | Piece of glass/acrylic (40cmx25cm) | Glass supplier and cutter | 5 |
| 1 | Box/Container/Plant pot | Hardware Shop | 10 |
| Total : 68 |
If your exposure times are excessively long you may have to replace the glass. Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths. You need quartz glass or – less expensive but less transmission- acrylic (Perspex). Also raising the tubes and mirror up will make a difference too.
If you do replace the glass, get a lid. There’s a reason commercial UV boxes have a lid with an interlock to cut the power. You wont get cataracts without prolonged exposure but still… why risk it?
Hi Tom,
Thanks for the info, I’ll see how things go with the glass and if exposure time is too long, then I will try acrylic. Also, for the lid, I have a piece of wood with foam stuck to one side that covers the entire area of glass. So I would put that on top, then switch the lamps on, but I get your point its not the ideal situation.