Tom, I apologize for not getting back to this thread for so long. I use a 7.5 watt, round frosted night light bulb, that is mounted inside a custom made (metal soup can) housing. The housing is suspended 30 inches above the work surface of my darkroom, and is stopped down with a black paper diaphragm to a 1/8" hole.
To calibrate this light source for preflashing paper negatives, I did a test strip series, in increments of 2 seconds each, using my darkroom's enlarger timer connected to the light source. For my process (Arista brand grade 2 glossy RC paper) I preflash to 8 seconds. I also rate this paper negative media at a 'speed' (exposure index) of around 2.
The preflashing is done such that if no additional exposure were given, the paper would acquire a faint, light gray tint.
I also develop the paper negatives using a diluted paper developer. For instance, using Agfa Neutol WA, I'll use a 1:20 dilution, and develop by inspection.
These paper negatives scan well for quick internet postings, but they also contact print nicely. I've also enlarged them from 4x5 to 11x14; I had to open up the enlarger lens all the way, and still use an exposure time of over a minute. In my condensor enlarger, the paper backing of the paper negative makes it kind of work like a diffusion enlarger would.
Not only for pinhole purposes, but I've experimented with alternative lenses on my Speed Graphic, with paper negative media. For instance, I use the front objective element from a 7x50 binocular, which just unscrews from the barrel of the binocular, and mounts to a simple plywood lens board to the Speed. I run this lens wide open at F3, for images with narrow DOF and 'swirly bokeh'. As an example, see my avatar image, shot with the binocular lens onto paper negative media. See the 'Alternative Photography' section of F295 for more great ideas around adapted optics for photographic purposes.
~Joe