What are these/what are they useful for?

[sjaustin]

Cleaning out the parts drawers, and found a few things that I'm not sure about. What type of vactrol is this? And what are these ICs good for?

[Aristatertotle]

Those photocouplers look like these: http://www.smallbear-electronics.mybigcommerce.com/photocouplers-macron-mi1210clx-series/ and they are a vtcl5c3 clone which is used in a good amount of modulation circuits for delays, envelope filters, phasers, etc.

The op27 is a low noise single opamp and I've seen them used in some pro audio schematics inputs on mixer channels, but I haven't seen them used in pedal stuff.

[drog_trog]

Yea im sure ive had them vacts from Smallbear years ago now

[sjaustin]

Yep, I'm pretty sure I remember ordering them from SBE now. Thanks!

No idea how I came by those op amps though...

[pickdropper]

Just an FYI on the Macrons.  We used them when prototyping the Parallax and had headroom issues.  The circuit functioned, but they weren't a direct drop in the VTL5C3.  The xVive that SmallBear also carries is a direct drop in, though.

They should be usable in some fashion, just keep in mind that there might need to be some tweaking.