Quote Originally Posted by Jarvman View Post
That's great help Trevor, thanks a lot again. I'm getting into pt/pd myself but will also be using it for cyanotypes too. How did you rig the lights up to an enlarger timer? that's a very sweet idea. My cousin is making me a 12x16 contact printing frame so an exposure unit the same size as yours would be ideal. likewise, I'd like the opportunity of printing larger than 10x8 if I wanted to. Initially I was just going to use 2 lamps with uv bulbs either side of the print, would that idea have fallen flat on its face? Could you give me the exact dimentions of the cabinet please. I'll go order the bulbs today.
Gareth, the interior dimensions are; 17" high x 16.1/4" wide (this would be too small if you are using a contact frame for 12x16" prints) x 15" deep. This little cupboard is an ideal size for me as it sits on the floor under the enlarger bench.

All nine lamps are wired in parallel, 3 rows of three, to provide me with not only light intensity but evenness of illumination (very important). The lights are wired to a terminal block and from there a single 3 core cable is then connected to a Viponel electronic timer which has an exposure range of 0.1 second to 16 minutes, anything longer I just hit repeat. If you are going to use an enlarger timer make sure it is powerful enough to take a total of at least 300W (my lamps are a total of 225W). The lights are fitted to a removable shelf that I can slide out for maintenance if need be.

I've also fitted an electric fan (separate circuit) to help cool things down during long exposure times. Although the cabinet is well ventilated; slight gap below door and two adjustable louvers at the top to allow free circulation of air.

When I have to dodge and burn I wear sunglasses, just to be safe, as the door is open and the UV light is quite bright. This is another reason I wanted the light box on the floor so its away from eye level. Although BLB UV lamps are safe if you use sensible precautions.

Hope all goes well and do let me know how you get on.