I came across this interesting project. The guy decided to make UV PCB exposure box made of UV light LED’s. The main reason why he used LED was the power dissipation and compactness. Assuming that one UV tube would take about 6W while one UV LED would take about (20mAx3.2V=64mW). Most of that energy UV tubes dissipate as heat energy.
So he took:
54 x UV LEDs of 400nm (6000 – 7000 mcd) – 100 units in Ebay costed 12€;
18 x 68ohms resistors 1/4W – 0,36 €;
1 connector – 0.50€;
1 electrolytic condenser of 2200uF – 30v;
1 Eurocard Plate 100×160 about 5 € ;
The the plate of LEDs is powered by 12V power supply. LEDs radiation angle is 20º , so they took about 8cm heigh box that light could cover the whole PCB area when distances between LEDs are 18mm.
Download circuit and PCB from original site.