30 Sep
2008
30 Sep
'08
9:55 a.m.
Chris Elmquist wrote:
BTW, where does a guy find the nice RED plastic lens
that is usually put
in front of a bank of 7-segment displays to hide the view of the parts
and show only the lighted segments showing through?
Is it just red plexiglass or is there a specific color and transmissive
capability that is typically used?
I bought a piece of this stuff in the 1970s, for a clock project and I
also used some of it on a 3-digit DVM (both of which I still have, and
still work). It was a neutral grey colour, and circularly polarized.
I think the idea was that any light reflecting off the internal parts
would be attenuated by the polarization. I got the filter material
from Maplin's, who are still in business, but I
don't think they still
sell it.
I like playing with RED LEDs too and have a bunch of
clocks and things
to build and want to put such a filter/lens in front of them.
On the DVM, I also painted the PCB and jumper wires, etc., matt black.
--
John Honniball
coredump at gifford.co.uk