18 Dec
2011
18 Dec
'11
12:07 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 number of LDRs in a B(A-baed bottle (about the size of an
^^^
That should have been B9A (Noval, 9 pin miniature), of course.
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.