UV LED Exposure Box

Sometimes I make some PCBs with the photo resist method which is basically printing a project through a design software (eagle in my occasion) with a laser printer, exposing to UV light for an amount of time (10 mins) and through chemical solution-etching have the final product. I wanted to upgrade the old fluoroscent lamp my dad used to have so I made this pcb based on 2 ideas by "djhamer" and "bulb66" at instructables. This time I use 5mm Round Top Ultra Violet LED UV Light 3000MCD. The use of arduino as a timer, I find it as an extra with no use since 2 minutes now are very good for the exposure of a board. The schematic is very easy to follow and this is a project that can be finished in an afternoon. Lastly all the resistors are 1/4 watt and because I didn't had 75 R resistors I used in parallel 1 resistor of 100R and 1 resistor of 220 R which through the formula 1/R1 + 1/R2 = 1/Rr1,2 gave the final R which was nearly 70 R, and it was very good.