[sdiy] optocouplers/Vactrols

[Barry Klein]

I happened across a package of plastic beads that supposedly melts in hot
water and then you can mold into whatever shape you want and it hardens.
$7.50 for a 6"x2" package or so.  Should work for this. 

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Paul Higgins
Sent: Tuesday, October 19, 2004 10:49 AM
To: Metrophage
Cc: synth-DIY
Subject: Re: [sdiy] optocouplers/Vactrols

Well, that explains why I couldn't find any optocouplers on the 
Hamamatsu website, only LDRs.  And I have heard that Clairex has 
dropped most if not all of their optocouplers from their product line.  
Oh, for the days when I could get a CLM6000 here in Minneapolis rather 
than having to mail order...and now we can't even get them by mail 
order.  This nostalgia is making me feel old...

A bit more bad news: I just got an email from a Silonex rep regarding 
their "Audiohm" optocouplers, and they have dropped their NSL-37 and 
NSL-39 models due to their molding contractor going out of business and 
"taking the housing mold with him".  They still carry the rest of the 
line (for now) including the popular NSL-32 models.  So pretty soon we 
may be back to making these things by hand.  Actually, Magic Parts 
(guitar amp parts supplier) does just that; they sell a "Fender Vibrato 
LDR" for $14 (wholesale price!) that from the picture looks 
suspiciously like a 30-second job with some heatshrink and a butane 
lighter.  I'm not kidding; I see no evidence of black paint or silicone 
compound to fill in the gaps and make it really light-tight.

I've got a much better approach than Magic Parts: it involves using a 
two-part super glue/catalyst combo you can get at a woodworking store 
(the catalyst makes the glue dry perfectly clear in about a second), a 
flat-top yellow LED glued to the LDR, heatshrink, and black model paint 
or silicone RTV compound (applied with a very narrow tip) to fill the 
gaps.  I've also seen people use 35mm film canisters with holes punched 
in the bottom for the leads; kind of bulky, but it works.  With the 
right LDR and construction, you can get pretty good performance even 
from DIY "Vactrols".

-PRH

On Tuesday, October 19, 2004, at 08:51 AM, Metrophage wrote:

> I don't prefer any yet, I am just getting into them, like it sounds you
> are. Each manufacturer makes units with various respective resistances
> and response times.
>
> Clairex and Hamamatsu appear to be dropping their production of many,
> if not all, analog photocouplers. There are still quite a few out
> there. Compare specs for the values you need!
>
> CJ