CQY80N, is it just a vactrol?

[altfidelity]

Hi,

I've recently stumbled upon CQY80N component inside a limiter (clipper?) circuit.
It seems like a Optocoupler packed inside of a opamp.
Are there any other designs using this component?

https://cdn-reichelt.de/documents/datenblatt/A500/CQY80#TEM.pdfhttps://www.vishay.com/docs/83533/83533.pdf

 

[gyraf]

No, it's a semiconductor photo transistor, not a ldr.

For bypass switching.

 

[altfidelity]

OK, I see it now, its just a switching mechanism. I totally misinterpret the limiter circuit than. I saw "optocoupler" in specs, got excited and carried away,

So what does the "limit" function actually do?
I see that it connect/disconnect the opamp from 15V voltage feed, but what does that mean in context of this OTA compressor?
It seems to be independent of threshold and ratio control?

 

[gyraf]

it adds a big +DC component through R39 (2K2) to inverting input of IC6B, pulling its output negative, thus preventing T4 to be able to turn on, > so no attack/release, > so no compression/limiting

..like turning the threshold to +infinite, thereby bypassing compression

 

[altfidelity]

...essentially bypass button.

I was hoping the button labelled "limit on/off" would be additional limiter/clipper in the circuit, not just a bypass for compression.
Weird/misleading designation of the button from manufacturer.

Ughh, now when i think about, the bypassing the unit would be problematic, because of gain staging & the volume differences, right?
The output volume pot is unaffected by the bypass button...clumsy.

thanks @gyraf I think you might just save me couple of euros & frustration. I believe I'll pass on purchasing this unit....