question about optic couplers

[John Fisher]

Hello,
I was thinking about cloning a Soldano amp and I noticed in the circuits that I have seen, the use of some optic couplers for switching. I understand the principal involved but can anyone tell me more specifically what devices are used? Are these devices light controlled diacs or are they light controlled photo resistores? Any part number references?
Thanks in advance!
John Fisher

[Steve Conner]

They're a little plastic tube with a LED glued in one end and a light-dependent resistor in the other. One popular brand is the "Vactrol" made by Perkin-Elmer.

VTL5C Series from PerkinElmer

Guitar amps commonly use the VTL5C series for channel switching and vibrato, I can't remember which part exactly. If you can get the light-dependent resistors (I remember they used to be popular items for hobbyist projects, but RoHS may have hit them because they were made of cadmium) there's nothing stopping you making your own.

http://en.wikipedia.org/wiki/Photoresistor

[Enzo]

Photocells - photoresistors

Jameco has a whole selection of them, various specs, cost a dollar or two.

www.jameco.com

[John Fisher]

Thanks guys! It's been a while since I've gotton into this. It's been more guitar building and taking care of of baby son.
I have many times before made the optic couplers using the photo risistor and led setup for projects such as compressors and the photo resistors are readily available where I am at. Mexico is still a DIY heaven compared to other places.
I guess I was just wondering if in the situation of the Soldano amp switching they used anything else. Fast digital switching as not really necessary in that situation. When I would buy the photo resistors, I would always buy several and check them with a VOM as there are almost none that are perfect and they vary in quality. Perfect in that they go completly on or completly off with infinite resistance or the perfect conductor although they can in some cases come very close.
Cool! now I can build my Soldano super lead. wee!!

BTW! If I was to build a Soldano Atomic 16, will that still kick ass and give me that Clapton and Mark Knofner tone. I don't really want a huge amp. It is the preamp choice I am mostly looking for. Thanks!