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Re: looking for LED filter plastic
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Moosefet and Paul Mathews referred to a type of lenticular filter film
which restricts the transmission of light to some angle either side of
90 degrees. Rear projection TVs also use a lenticular layer, and I have
some pieces of that if you want to try it (I'm also in Melbourne, and
have a snipped-for-privacy@gmail.com email address). The material I have is made
from threads of glass fibre laid parallel on a film adhered to a 3mm
plastic sheet. A regular source would be expensive, unless the 3M film
is available at a decent price. Just email privately and arrange to
drop by.

Clifford Heath.

Re: looking for LED filter plastic

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Thanks Clifford,

I'm after a commercial quantity so I have put some emails around to some
companies and I will see what that comes up with.

Ultimately I think I need brighter LEDs and I am now looking at some
kingbright LEDs that are advertised as being suitable for traffic and
parking signs.

I am yet to have a really good close look at our local 60km/h to 40km/h
changing speed limit signs. I thought that they had some sort of filter, but
that may not be the case.

The whole bright LED thing was a little worrying - while I am happy with PWM
driver circuitry, I wonder what the long term reliability effects are of
driving leds higher than 20ma. Its difficult to say before actually trying
it and seeing how long it lasts.

I am also looking at changing the red led colour to a green. From the
datasheets that I have seen, Green leds appear to throw out more mcd per

I am yet to find a really good difinitive example of what exact mcd rated
leds (and what brand of led) are used in what signs.

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