1. Home
  2. Electronics Design
  3. CdS optocoupler compressors - still viable?

CdS optocoupler compressors - still viable?

Are audio compressors using the CdS -style optocouplers still viable for new designs? These were present in a lot of older analog solid state amps and mixers (80's and 90's). But the parts are leaded devices that aren't too easy to handle using SMT assembly. Maybe DSP and A/D conversion is making them obsolete?

I see that Perkin Elmer (the old EG&G) and Silonex still make them, but those aren't carried by many distributors, another warning sign. And the ones that do carry them seem to charge a lot... over $5 each.

Looking at the data sheets I don't see much information about how the parts are affected by heat, or whether they wear out with age.

This would be for an audio project, so the very common "phototransistor" type parts are more difficult to use.

So, are these CdS parts just about to disappear? They seem capable of making a nice compressor, in principle.

Reply to
mw
Loading thread data ...

I dont think that the P-E optos will be discontinued, it is a rather a specialised market, they are over £5 each in the UK. So thats why they are available from specialists, not the Big distro's

TFPro.com has just released a opto compressor. Its an old fashioned way of compressing and you are quite limited in the release time department. But they can sound great. Try and get hold of the LA3, 4 circuits

martin

Reply to
martin griffith

They are too handy for use in niche applications to stop making them. Been using Silonex parts for years. Just bought 4 this morning, standard stock item from Farnells, for equiv of $2 each. regards john

Reply to
john jardine

They're great. The good ones from Silonex have very low THD too. Don't need DC trimming like VCAs either.

Farnell has the Silonex parts at a sensible price.

formatting link

Silonex tried to make them SMT but failed - I don't know why.

I've alslo used some Chinese 'Eagle' branded couplers. Very primitive construction internally but they work.

Graham

Reply to
Pooh Bear

Just got quoted £5.43 for the P.E equiv's, ....

martin

Reply to
martin griffith

formatting link

I found them at Allied Elec, $2.14 each for the NSL-32 (it seems like a popular choice, 992 in stock). Pretty good price.

Thanks, everyone.

mw

Reply to
mw

You mean the old Vactrols ?

They've always been pricier.

Another source of CdS couplers used to be Hamamatsu Photonics btw. They were pricey too though. If you can use the Silonex parts they're likely your best bet.

Graham

Reply to
Pooh Bear

How are CdS cells affected by the RoHS stuff? Cadmium's pretty toxic, worse than lead I thought.

--
   Wim Lewis , Seattle, WA, USA. PGP keyID 27F772C1
Reply to
Wim Lewis

Just say that it is for the Coke Cola company, no problems

formatting link
formatting link

martin

Reply to
martin griffith

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.