You really should go for the simplest setup. I would add to the 15 watt bulb, a $6 light dimmer from Home Despot. A timer would also be a good idea but if you adjust lamp distance/light output to give you an exposure of 10 seconds or so, you could use a watch. As long as your light is a foot or so from your negative (or more) you will have no issues with uneven light.