17 Dec
2011
17 Dec
'11
1:33 p.m.
On 12/17/2011 01:36 PM, Tony Duell wrote:
I rememebr reading about a Mullard (Philips) device
that consisted of a
filament and a numbero LDRs in a B(A-baed bottle (about the size of an
ECC83/12AX7). I think the number was RPY13. It appears to have been a
predecessor of the optoisolator. I've never seen one.
Oh wow, that sounds like fun!
What do they use for LDRs nowadays? cThe ones I used
were cadmium
sulphide (CdS), but I beleive cadmium is frowned upon now :-(
It may be, but CdS cells abound, and I don't see them going away
anytime soon. There's so little cadmium in them that I really don't see
it ever being a problem.
-Dave
--
Dave McGuire
New Kensington, PA