[sdiy] what are these?

[Cynthia Webster]

on 10/23/04 7:08 PM, Roy J. Tellason at rtellason at blazenet.net wrote:

> On Saturday 23 October 2004 05:37 pm, Roy J. Tellason wrote:
>> I'm still sorting through parts...
>> 
>> In this small bag labeled "optoisolators" I find these five things.  About
>> an inch long more or less,  mayba a cm wide,  and irregular in contour --
>> there are two wires coming out of each end,  and the rest is covered by a
>> layer of heatshrink.  Markings are "SIGMA 932" and "301T1-PC" and "26148".
>> I'm not measuring anything with an ohmmeter between pairs of wires...
>> 
>> Reminds me a little bit of those units that Fender used to use for
>> "vibrato" except that these were obviously mounted on some board or other,
>> wires are fairly short and all pointed in the same direction.
>> 
>> Any of you guys have any ideas about these?
> 
> Ok,  I opened one up,  since there only seemed to be 3 rather than 4 leads
> coming out of it.  And what do I find?  Another layer of heatshrink,  this
> one thin and yellow.  I can see what looks like the tip of a neon bulb
> peeking out of one end of the shrink,  and this yellow stuff is apparently
> transmissive enough that this time when I put the meter across the photocell
> I get readings that drop down to close to 100 ohms as I get closer to the
> lamp over my desk.
> 
> Regular optos I can find a use for (and I have some,  and plans for them),
> but not ones driven by a neon bulb.  Any of you guys have a use for these?
 
Could these be for detecting the presence of AC Mains?

Cynthia