Hi all,

Previously, I mentioned that I built an amphometer using a 16F84 a dual
comparator and two LDRs. As a vehicle passed over the top of the LDRs,
the light level change altered the output states of the comparators and
the PIC calculated the speed from the difference in time. Pretty simple,
and it was verified with high speed video and is quite accurate. The
problem is varying light levels and the need to compensate for this to
avoid false triggering.

After much mucking about, I decided to still use the PIC section, but
use 2 laser modules instead so that each beam can be broken as the
vehicle passes. These are only $8 each for a 3-4.5V 5mW device complete
with lens.

Has anyone used LDRs as a detector for laser light, or should I use
something else?
--
Best regards

Tony

http://www.picnpoke.com
Email sales@picnpoke.com