3 Tech Q's

[paulster]

Tony

Going off topic a bit but the one thing to be wary of with Vactrols (aside from the fact that they aren't RoHS compliant if that's a concern) is that their capacitance can become significant, so you may need to voice around that as well as the high/low resistance rather than on/off states.

[talbany]

Paulster

Thanks for the heads up there!!!... Yeah I remember several things I didn't particularly like about them... The dark resistance was one and being ROHAS like you mentioned always worried about them pulling them for that reason and being left dry of relays...It would be interesting to do a side by side test to see if the LDR's had an audible difference in tone...If you go to Randall Aiken's site under Tech/Data sheets he lists several he recommends..The axioms have proven their functionality and reliability...


Tony VVT

[Structo]

I was looking at the response time on those Vactrols.

Turn on varied from 2.5ms to 3.5ms and turn off was 35ms and 500ms.

Would the turn on delay be noticeable and the turn off?

Does it sound like a hard switch or does it come on soft?

[paulster]

I was looking at using them for a project, bought a load, and then decided to use relays in the end after I simplified the scope and realised it would be far simpler to use a DPDT relay than 4 of these per switch!

When I was researching them (several years ago) the best I was able to find were the VTL5C9 models, which had the following specs:
On resistance: 630R
Off resistance: 50M
Turn-on to 63% R-on: 4.0ms max (nice)
Turn-off to 100K: 50ms max (also pretty good for these things)
Capacitance: 5pF (not too bad)

There may be better ones available now but these still looked pretty promising.

[Structo]

Man, I can't find the file but, what are those IC's that have the led switching in them?
Was it Gary that talked about it.

[paulster]

You mean the ones Allyn and Dana use in their Komet Touch Response™ switching boards? Those were PS7141 devices.