Homebrew_PCBs

I like this idea of using a UV sensor - but this is a DIY group, so surely we can design and make something more purpose specific than the devices available on eBay.

I remembered that LEDs can be used as partial spectrum photo sensors, generating a voltage from wavelengths shorter than a specific threshold. If we use two LEDs - one just above the photoresist's sensitivity and one just below, an Arduino or similar might subtract one from the other to get an exposure value and drive a few 7 segment LEDs to count up from 0.

Each photoresist type would have a specific numeric value for proper exposure and should be relatively consistent regardless of atmospheric conditions.

Of course, I do not have the know-how to design or program this, but I would be happy to make one if someone would just show me how.

--- In homebrew_pcbs@yahoogroups.com, <rjshaw@...> wrote:

> With the 10W UV LED I described in recent messages, I measured the
> amount of light falling on a flat surface, like the PCB, according to
> how far from the direct perpendicular point of illumination this is.