Re: Looking for data on 1980s CDS cells - VACTEK VT212/VT212L

On 8/28/2024 8:19 PM, John Robertson wrote:

I'm trying to find a modern CDS cells to replace these old timers (1982) from the 70s, I did find a catalogue page for these CDS cells, but the details are not as useful to me as perhaps they would be to someone handy with using CDS cells.
 The ratings are:
VT212L - 6 R1, 5 R2
VT212  - 7.8 R1, 5 R2
 R1 defined as 2fc resistance in K Ohms (tolerance +/- 33.3% @ 2850K Source
R2 defined as min dark resistance (Megohms) in 5 sec.
 Having a heck of a time matching these to more modern cds such as carried by DK or Mouser. I tried the NSL-06S53, but its light resistance is too sensitive and nothing else on DK was better.
 Anyone have a VACTEK catalogue who could scan the pages that might help?
 I suspect that PerkinElmer bought out Vactek as they used similar part (VT200x) numbers as early as 2001 that I could find on web.archive.org, but that archive doesn't have the parts books captured.
 Bitsavers doesn't list it, nothing on ebay either...
 Why am I bothering? I have a rifle gallery (http://www.bonanzagallery.com/) that uses flash tubes in the rifles to trip the cds cells in the targets and there are around 70 cds cells. A number of them are failing so I want to replace them with something that will work reliably.
 Thanks as always for your time!
 John :-#)#
 

Here's a possibility: diffuse the light hitting the
innards of the cds by painting or scratching its lens.
You could try sliding it across sandpaper - say 220 grit
for some specific distance - the see if the sensitivity
has been reduced the right amount.  Or try translucent
paint. If you can get it to work properly with one cds,
the next step would be to set up a process where every
cds would be identically painted or scratched.
Ed