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1957 LED

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  1957 LED hancock4@bbs.cpcn.com - 2015-12-10 11:03 -0800
    Re: 1957 LED Al Kossow <aek@bitsavers.org> - 2015-12-10 11:06 -0800
      Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-10 14:44 -0500
        Re: 1957 LED hancock4@bbs.cpcn.com - 2015-12-11 07:41 -0800
          Re: 1957 LED Ahem A Rivet's Shot <steveo@eircom.net> - 2015-12-11 16:37 +0000
          Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-11 14:42 -0500
      Re: 1957 LED philo <philo@privacy.net> - 2015-12-10 13:56 -0600
        Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-10 22:59 -0500
          Re: 1957 LED "Osmium" <r124c4u102@comcast.net> - 2015-12-11 08:20 -0600
            Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-11 14:33 -0500
        Re: 1957 LED Quadibloc <jsavard@ecn.ab.ca> - 2015-12-13 07:58 -0800
          Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-13 13:00 -0500
        Re: 1957 LED Lon <lon.stowell@comcast.net> - 2015-12-13 12:48 -0700
          Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-14 09:07 +0000
            Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-14 11:47 -0500
            Re: 1957 LED rpw3@rpw3.org (Rob Warnock) - 2015-12-16 14:55 +0000
              Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-16 16:32 +0000
                Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-16 14:17 -0500
                Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-16 18:15 -0600
                  Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-17 07:58 +0000
                  Re: 1957 LED Andrew Swallow <am.swallow@btinternet.com> - 2015-12-17 13:21 +0000
          Re: 1957 LED Ingo Paschke <ipaschke@lpclabs.de> - 2015-12-14 11:11 +0100
      Re: 1957 LED Stephen Wolstenholme <steve@easynn.com> - 2015-12-11 10:58 +0000
        Re: 1957 LED Lon <lon.stowell@comcast.net> - 2015-12-13 12:50 -0700
          Re: 1957 LED Stephen Wolstenholme <steve@easynn.com> - 2015-12-14 12:57 +0000
            Re: 1957 LED "gareth" <no.spam@thank.you.invalid> - 2015-12-14 14:07 +0000
              Re: 1957 LED Stephen Wolstenholme <steve@easynn.com> - 2015-12-14 14:33 +0000
      Re: 1957 LED hancock4@bbs.cpcn.com - 2015-12-11 07:31 -0800
        Re: 1957 LED Quadibloc <jsavard@ecn.ab.ca> - 2015-12-13 07:42 -0800
          Re: 1957 LED Ahem A Rivet's Shot <steveo@eircom.net> - 2015-12-14 09:39 +0000
          Re: 1957 LED Jon Elson <jmelson@wustl.edu> - 2015-12-14 17:07 -0600
            Re: 1957 LED Alfred Falk <falk@arc.ab.ca> - 2015-12-15 18:53 +0000
              Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-15 15:05 -0500
                Re: 1957 LED hancock4@bbs.cpcn.com - 2015-12-16 07:32 -0800
                  Re: 1957 LED Alfred Falk <falk@arc.ab.ca> - 2015-12-16 17:23 +0000
                  Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-16 14:23 -0500
                    Re: 1957 LED Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-16 20:13 +0000
                      Re: 1957 LED hancock4@bbs.cpcn.com - 2015-12-16 13:15 -0800
                      Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-17 14:53 -0500
                        Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-17 14:17 -0600
                          Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-18 19:43 -0500
                            Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-20 20:02 -0600
                            Re: 1957 LED hancock4@bbs.cpcn.com - 2015-12-21 10:31 -0800
                              Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-21 14:53 -0500
                                Re: 1957 LED mausg@mail.com - 2015-12-21 20:27 +0000
                    Re: 1957 LED Uncle Steve <stevet810@gmail.com> - 2015-12-17 18:48 -0500
            Re: 1957 LED davidmylastname@acm.org (David Griffith) - 2015-12-16 02:43 +0000
            Re: 1957 LED Mike Spencer <mds@bogus.nodomain.nowhere> - 2015-12-16 17:44 -0400
    Re: 1957 LED scott@slp53.sl.home (Scott Lurndal) - 2015-12-10 19:13 +0000
      Re: 1957 LED "gareth" <no.spam@thank.you.invalid> - 2015-12-10 20:17 +0000
        Re: 1957 LED Lawrence Statton <lawrence@sengiuo.mx> - 2015-12-10 17:10 -0600
        Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-10 23:00 -0500
          Re: 1957 LED isw <isw@witzend.com> - 2015-12-10 21:21 -0800
            Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-11 08:01 +0000
              Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-11 14:30 -0500
              Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-11 15:36 -0600
                Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-12 07:55 +0000
                  Re: 1957 LED mausg@mail.com - 2015-12-12 11:20 +0000
                    Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-12 15:39 +0000
                    Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-12 10:50 -0500
                      Re: 1957 LED Stan Barr <plan.b@bluesomatic.org> - 2015-12-13 08:00 +0000
                        Re: 1957 LED "gareth" <no.spam@thank.you.invalid> - 2015-12-13 11:10 +0000
                Re: 1957 LED Lon <lon.stowell@comcast.net> - 2015-12-13 12:51 -0700
          Re: 1957 LED "gareth" <no.spam@thank.you.invalid> - 2015-12-11 10:59 +0000
            Re: 1957 LED Ahem A Rivet's Shot <steveo@eircom.net> - 2015-12-11 15:46 +0000
              Re: 1957 LED "gareth" <no.spam@thank.you.invalid> - 2015-12-11 17:37 +0000
                Re: 1957 LED Ahem A Rivet's Shot <steveo@eircom.net> - 2015-12-11 18:34 +0000
                  Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-11 14:49 -0500
                  Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-11 15:39 -0600
                    Re: 1957 LED Bob Eager <news0005@eager.cx> - 2015-12-11 22:46 +0000
                    Re: 1957 LED Michael Black <et472@ncf.ca> - 2015-12-11 19:07 -0500
                      Re: 1957 LED Bob Eager <news0005@eager.cx> - 2015-12-12 01:04 +0000
                      Re: 1957 LED Ahem A Rivet's Shot <steveo@eircom.net> - 2015-12-12 08:54 +0000
          Re: 1957 LED hancock4@bbs.cpcn.com - 2015-12-11 11:52 -0800
            Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-11 15:46 -0600
              Re: 1957 LED Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-11 22:56 +0000
          Re: 1957 LED "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-11 15:35 -0600
          Re: 1957 LED Quadibloc <jsavard@ecn.ab.ca> - 2015-12-13 07:51 -0800
    Re: 1957 LED Lawrence Statton <lawrence@senguio.mx> - 2015-12-10 17:09 -0600

Page 4 of 4 — ← Prev page 1 2 3 [4]

#155136

On Sat, 12 Dec 2015 10:50:12 -0500, Michael Black <et472@ncf.ca> wrote:
>>
> You can't get more generic than capacitors.  But it can be tedious, people 
> will often replace them all because once one goes, likely others of the 
> same vintage will go soon enough.  If you have the radio open, might as 
> well change them all together.  I don't know about this Racal, but some 
> receivers are legendary in being really difficult to get to all the places 
> that need replacement capacitors (which is another good reason to change 
> them all once you are working on the radio).

Thankfully the Racal RA1792 is modular construction so in service
modules can be quickly swapped.  Just unplug the module put it on the
bench.

http://www.recelectronics.co.uk/ra1792.htm if you're really interested...

-- 
Stan Barr     plan.b@bluesomatic.org

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#155141

"Stan Barr" <plan.b@bluesomatic.org> wrote in message 
news:slrnn6q9cd.8ns.plan.b@ID-309335.user.uni-berlin.de...
> On Sat, 12 Dec 2015 10:50:12 -0500, Michael Black <et472@ncf.ca> wrote:
>>>
>> You can't get more generic than capacitors.  But it can be tedious, 
>> people
>> will often replace them all because once one goes, likely others of the
>> same vintage will go soon enough.  If you have the radio open, might as
>> well change them all together.  I don't know about this Racal, but some
>> receivers are legendary in being really difficult to get to all the 
>> places
>> that need replacement capacitors (which is another good reason to change
>> them all once you are working on the radio).
>
> Thankfully the Racal RA1792 is modular construction so in service
> modules can be quickly swapped.  Just unplug the module put it on the
> bench.
>
> http://www.recelectronics.co.uk/ra1792.htm if you're really interested...

Should you decide to bin it, I'd be happy to be the recycling bin for it!

Gareth, G4SDW
 

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#155157

On 12/11/2015 14:36, Charles Richmond wrote:
> "Stan Barr" <plan.b@bluesomatic.org> wrote in message
> news:slrnn6l0nl.8tc.plan.b@ID-309335.user.uni-berlin.de...
>> On Thu, 10 Dec 2015 21:21:14 -0800, isw <isw@witzend.com> wrote:
>>> In article <alpine.LNX.2.02.1512102259410.27954@darkstar.example.org>,
>>>  Michael Black <et472@ncf.ca> wrote:
>>>
>>>> On Thu, 10 Dec 2015, gareth wrote:
>>>>
>>>> > "Scott Lurndal" <scott@slp53.sl.home> wrote in message
>>>> > news:m9kay.15466$qz7.15339@fx01.iad...
>>>> >> hancock4@bbs.cpcn.com writes:
>>>> >>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
>>>> >>> It was in C&A 09-1957, pg 19.
>>>> >>
>>>> >> Photo-diode != LED
>>>> >
>>>> > Except that most LEDs are reciprocal to light of the same frequency.
>>>> >
>>>> But does that work both ways?
>>>>
>>>> I know people have seen problems with semiconductor diodes that pick up
>>>> light from a nearby lightbulb.  And certainly you can use an LED as a
>>>> receiver of light, though I suspect it's not too efficient.
>>>>
>>>> But can you put light through a diode not intended to generate
>>>> light, and
>>>> get light?
>>>
>>> Yes. Briefly.     8^}
>>>
>>> Isaac
>>
>> Cue old magazine article about a Noise Emmiting Diode :-)
>>
>
> And don't forget the "magic smoke".  After you let the "magic smoke" out
> of a circuit component, the component has been munged and is *no* good
> anymore!!! :-(
>

I wonder if the original cue was for the dark sucker diode, or possibly 
even the old write only memory.

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#155016

"Michael Black" <et472@ncf.ca> wrote in message 
news:alpine.LNX.2.02.1512102259410.27954@darkstar.example.org...
> On Thu, 10 Dec 2015, gareth wrote:
>> "Scott Lurndal" <scott@slp53.sl.home> wrote in message
>> news:m9kay.15466$qz7.15339@fx01.iad...
>>> hancock4@bbs.cpcn.com writes:
>>>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
>>>> It was in C&A 09-1957, pg 19.
>>> Photo-diode != LED
>> Except that most LEDs are reciprocal to light of the same frequency.
> But does that work both ways?
> I know people have seen problems with semiconductor diodes that pick up 
> light from a nearby lightbulb.  And certainly you can use an LED as a 
> receiver of light, though I suspect it's not too efficient.
> But can you put light through a diode not intended to generate light, and 
> get light?

Oh! for the days of scraping the black paint from an OC71 to
make an OCP71! 

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#155033

On Fri, 11 Dec 2015 10:59:51 -0000
"gareth" <no.spam@thank.you.invalid> wrote:

> "Michael Black" <et472@ncf.ca> wrote in message 
> news:alpine.LNX.2.02.1512102259410.27954@darkstar.example.org...
> > On Thu, 10 Dec 2015, gareth wrote:
> >> "Scott Lurndal" <scott@slp53.sl.home> wrote in message
> >> news:m9kay.15466$qz7.15339@fx01.iad...
> >>> hancock4@bbs.cpcn.com writes:
> >>>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
> >>>> It was in C&A 09-1957, pg 19.
> >>> Photo-diode != LED
> >> Except that most LEDs are reciprocal to light of the same frequency.
> > But does that work both ways?
> > I know people have seen problems with semiconductor diodes that pick up 
> > light from a nearby lightbulb.  And certainly you can use an LED as a 
> > receiver of light, though I suspect it's not too efficient.
> > But can you put light through a diode not intended to generate light,
> > and get light?
> 
> Oh! for the days of scraping the black paint from an OC71 to
> make an OCP71! 

	Only to discover that the new ones were filled with an opaque blue
gel and you were stuck with paying for a real one.

-- 
Steve O'Hara-Smith                          |   Directable Mirror Arrays
C:>WIN                                      | A better way to focus the sun
The computer obeys and wins.                |    licences available see
You lose and Bill collects.                 |    http://www.sohara.org/

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#155042

"Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message 
news:20151211154649.335634cf5f6d52729fd8857f@eircom.net...
> On Fri, 11 Dec 2015 10:59:51 -0000
> "gareth" <no.spam@thank.you.invalid> wrote:
>
>> "Michael Black" <et472@ncf.ca> wrote in message
>> news:alpine.LNX.2.02.1512102259410.27954@darkstar.example.org...
>> > On Thu, 10 Dec 2015, gareth wrote:
>> >> "Scott Lurndal" <scott@slp53.sl.home> wrote in message
>> >> news:m9kay.15466$qz7.15339@fx01.iad...
>> >>> hancock4@bbs.cpcn.com writes:
>> >>>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
>> >>>> It was in C&A 09-1957, pg 19.
>> >>> Photo-diode != LED
>> >> Except that most LEDs are reciprocal to light of the same frequency.
>> > But does that work both ways?
>> > I know people have seen problems with semiconductor diodes that pick up
>> > light from a nearby lightbulb.  And certainly you can use an LED as a
>> > receiver of light, though I suspect it's not too efficient.
>> > But can you put light through a diode not intended to generate light,
>> > and get light?
>>
>> Oh! for the days of scraping the black paint from an OC71 to
>> make an OCP71!
>
> Only to discover that the new ones were filled with an opaque blue
> gel and you were stuck with paying for a real one.

The point being, of course, that in commercial products, the black paint
peeling off resulted in undesirable photo-electric effects, so requiring a 
change
to an opaque filling.

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#155048

On Fri, 11 Dec 2015 17:37:48 -0000
"gareth" <no.spam@thank.you.invalid> wrote:

> "Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message 
> news:20151211154649.335634cf5f6d52729fd8857f@eircom.net...
> > On Fri, 11 Dec 2015 10:59:51 -0000
> > "gareth" <no.spam@thank.you.invalid> wrote:
> >
> >> "Michael Black" <et472@ncf.ca> wrote in message
> >> news:alpine.LNX.2.02.1512102259410.27954@darkstar.example.org...
> >> > On Thu, 10 Dec 2015, gareth wrote:
> >> >> "Scott Lurndal" <scott@slp53.sl.home> wrote in message
> >> >> news:m9kay.15466$qz7.15339@fx01.iad...
> >> >>> hancock4@bbs.cpcn.com writes:
> >> >>>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
> >> >>>> It was in C&A 09-1957, pg 19.
> >> >>> Photo-diode != LED
> >> >> Except that most LEDs are reciprocal to light of the same frequency.
> >> > But does that work both ways?
> >> > I know people have seen problems with semiconductor diodes that pick
> >> > up light from a nearby lightbulb.  And certainly you can use an LED
> >> > as a receiver of light, though I suspect it's not too efficient.
> >> > But can you put light through a diode not intended to generate light,
> >> > and get light?
> >>
> >> Oh! for the days of scraping the black paint from an OC71 to
> >> make an OCP71!
> >
> > Only to discover that the new ones were filled with an opaque blue
> > gel and you were stuck with paying for a real one.
> 
> The point being, of course, that in commercial products, the black paint
> peeling off resulted in undesirable photo-electric effects, so requiring
> a change
> to an opaque filling.

	Yeah I heard that claim - it seemed specious, after all in most
commercial products the transistors were inside a box that didn't let a lot
of light in.

-- 
Steve O'Hara-Smith                          |   Directable Mirror Arrays
C:>WIN                                      | A better way to focus the sun
The computer obeys and wins.                |    licences available see
You lose and Bill collects.                 |    http://www.sohara.org/

[toc] | [prev] | [next] | [standalone]

#155057

On Fri, 11 Dec 2015, Ahem A Rivet's Shot wrote:

> On Fri, 11 Dec 2015 17:37:48 -0000
> "gareth" <no.spam@thank.you.invalid> wrote:
>
>> "Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message
>> news:20151211154649.335634cf5f6d52729fd8857f@eircom.net...
>>> On Fri, 11 Dec 2015 10:59:51 -0000
>>> "gareth" <no.spam@thank.you.invalid> wrote:
>>>
>>>> "Michael Black" <et472@ncf.ca> wrote in message
>>>> news:alpine.LNX.2.02.1512102259410.27954@darkstar.example.org...
>>>>> On Thu, 10 Dec 2015, gareth wrote:
>>>>>> "Scott Lurndal" <scott@slp53.sl.home> wrote in message
>>>>>> news:m9kay.15466$qz7.15339@fx01.iad...
>>>>>>> hancock4@bbs.cpcn.com writes:
>>>>>>>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
>>>>>>>> It was in C&A 09-1957, pg 19.
>>>>>>> Photo-diode != LED
>>>>>> Except that most LEDs are reciprocal to light of the same frequency.
>>>>> But does that work both ways?
>>>>> I know people have seen problems with semiconductor diodes that pick
>>>>> up light from a nearby lightbulb.  And certainly you can use an LED
>>>>> as a receiver of light, though I suspect it's not too efficient.
>>>>> But can you put light through a diode not intended to generate light,
>>>>> and get light?
>>>>
>>>> Oh! for the days of scraping the black paint from an OC71 to
>>>> make an OCP71!
>>>
>>> Only to discover that the new ones were filled with an opaque blue
>>> gel and you were stuck with paying for a real one.
>>
>> The point being, of course, that in commercial products, the black paint
>> peeling off resulted in undesirable photo-electric effects, so requiring
>> a change
>> to an opaque filling.
>
> 	Yeah I heard that claim - it seemed specious, after all in most
> commercial products the transistors were inside a box that didn't let a lot
> of light in.
>
But that sort of thing did happen.

I remember an article where someone was using a small signal diode as a 
varactor.  He was having problems, AC hum coming from somewhere.  Then he
realized the desk lamp over the board was light modulating this diode at a 
60Hz rate.  COvering the diode fixed it, an alternative wsa to find a 
diode that didnt' have a clear case.

   Michael

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#155071

"Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message 
news:20151211183415.fc6f3fea1533aabf7476e9c7@eircom.net...
> On Fri, 11 Dec 2015 17:37:48 -0000
> "gareth" <no.spam@thank.you.invalid> wrote:
>
>           [snip...]                   [snip...] 
> [snip...]
>
>>
>> The point being, of course, that in commercial products, the black paint
>> peeling off resulted in undesirable photo-electric effects, so requiring
>> a change
>> to an opaque filling.
>
> Yeah I heard that claim - it seemed specious, after all in most
> commercial products the transistors were inside a box that didn't let a 
> lot
> of light in.
>

I remember having a very early transistor radio that used germanium 
transistors.  These transistors were in little metal cans that I think block 
most all of the light to the transistor junctions.

-- 

numerist at aquaporin4 dot com

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#155077

On Fri, 11 Dec 2015 15:39:35 -0600, Charles Richmond wrote:

> "Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message
> news:20151211183415.fc6f3fea1533aabf7476e9c7@eircom.net...
>> On Fri, 11 Dec 2015 17:37:48 -0000 "gareth" <no.spam@thank.you.invalid>
>> wrote:
>>
>>           [snip...]                   [snip...]
>> [snip...]
>>
>>
>>> The point being, of course, that in commercial products, the black
>>> paint peeling off resulted in undesirable photo-electric effects, so
>>> requiring a change to an opaque filling.
>>
>> Yeah I heard that claim - it seemed specious, after all in most
>> commercial products the transistors were inside a box that didn't let a
>> lot of light in.
>>
>>
> I remember having a very early transistor radio that used germanium
> transistors.  These transistors were in little metal cans that I think
> block most all of the light to the transistor junctions.

Some of them were in glass enclosures. I used to file a groove round the 
enclosure, break it off, wash the semi-opaque jelly off, and refit the 
enclosure to make a cheap phototransistor.



-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#155083

On Fri, 11 Dec 2015, Charles Richmond wrote:

> "Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message 
> news:20151211183415.fc6f3fea1533aabf7476e9c7@eircom.net...
>> On Fri, 11 Dec 2015 17:37:48 -0000
>> "gareth" <no.spam@thank.you.invalid> wrote:
>>
>>           [snip...]                   [snip...] [snip...]
>> 
>>> 
>>> The point being, of course, that in commercial products, the black paint
>>> peeling off resulted in undesirable photo-electric effects, so requiring
>>> a change
>>> to an opaque filling.
>> 
>> Yeah I heard that claim - it seemed specious, after all in most
>> commercial products the transistors were inside a box that didn't let a lot
>> of light in.
>> 
>
> I remember having a very early transistor radio that used germanium 
> transistors.  These transistors were in little metal cans that I think block 
> most all of the light to the transistor junctions.
>
I'm not sure when plastic transistors came along, but yes, I think early 
transistors were strictly metal cased.

On the other hand, later transistors in plastic cases weren't clear 
plastic.  But it may be that early transistors, which were germanium, 
needed some space around the "chip", I know they had some problem in the 
long run, while silicon transistors, that eventually came to dominate, 
could be closer packed.

   Michael

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#155084

On Fri, 11 Dec 2015 19:07:35 -0500, Michael Black wrote:

> On Fri, 11 Dec 2015, Charles Richmond wrote:
> 
>> "Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message
>> news:20151211183415.fc6f3fea1533aabf7476e9c7@eircom.net...
>>> On Fri, 11 Dec 2015 17:37:48 -0000 "gareth"
>>> <no.spam@thank.you.invalid> wrote:
>>>
>>>           [snip...]                   [snip...] [snip...]
>>> 
>>> 
>>>> The point being, of course, that in commercial products, the black
>>>> paint peeling off resulted in undesirable photo-electric effects, so
>>>> requiring a change to an opaque filling.
>>> 
>>> Yeah I heard that claim - it seemed specious, after all in most
>>> commercial products the transistors were inside a box that didn't let
>>> a lot of light in.
>>> 
>>> 
>> I remember having a very early transistor radio that used germanium
>> transistors.  These transistors were in little metal cans that I think
>> block most all of the light to the transistor junctions.
>>
> I'm not sure when plastic transistors came along, but yes, I think early
> transistors were strictly metal cased.
> 
> On the other hand, later transistors in plastic cases weren't clear
> plastic.  But it may be that early transistors, which were germanium,
> needed some space around the "chip", I know they had some problem in the
> long run, while silicon transistors, that eventually came to dominate,
> could be closer packed.

As I implied in a previous post, some of the germanium ones were in a 
glass case, with some 'jelly' (light blue I think) filling the gap 
between that and the 'chip'.



-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#155094

On Fri, 11 Dec 2015 19:07:35 -0500
Michael Black <et472@ncf.ca> wrote:

> On the other hand, later transistors in plastic cases weren't clear 
> plastic.  But it may be that early transistors, which were germanium, 
> needed some space around the "chip", I know they had some problem in the 
> long run, while silicon transistors, that eventually came to dominate, 
> could be closer packed.

	I recall seeing an article about how some really small silicon
transistors were made, the phrase "surface passivated planar epitaxial" was
used, IIRC this process was credited for making it possible to encapsulate
transistors directly in plastic. The transistors in question were only just
big enough for the three leads at 0.1".

-- 
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C:>WIN                                      | A better way to focus the sun
The computer obeys and wins.                |    licences available see
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#155058

On Thursday, December 10, 2015 at 10:57:47 PM UTC-5, Michael Black wrote:

> But can you put light through a diode not intended to generate light, and 
> get light?

FWIW, electric motors can be reversed to become generators.  Back
in the 1930s, railways made use of this feature with something
called dynamic braking.  With it, to slow down the train, the
motors were switched to be generators, and the generated power
was fed into resistors.  The load slowed the train down, and
saved on wear on the friction brakes.

(Today, some systems return that generated power into the power
supply, so other trains can use it.  That requires some tricky
switchgear on both the train and wayside, but they have it now.)

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#155072

<hancock4@bbs.cpcn.com> wrote in message 
news:0d119fef-f0bc-4a84-9213-3a647e06ee48@googlegroups.com...
> On Thursday, December 10, 2015 at 10:57:47 PM UTC-5, Michael Black wrote:
>
>> But can you put light through a diode not intended to generate light, and
>> get light?
>
> FWIW, electric motors can be reversed to become generators.  Back
> in the 1930s, railways made use of this feature with something
> called dynamic braking.  With it, to slow down the train, the
> motors were switched to be generators, and the generated power
> was fed into resistors.  The load slowed the train down, and
> saved on wear on the friction brakes.
>

With some of the early Winchester disk drives, when shutting down the 
computer... one needed to run a "parking" program that unloaded the disk 
heads and moved them over a "landing zone".  Later drives were 
"self-parking";  when the power was removed from the drive, the spin-down 
inertia of the platters made use of the drive motor as a generator.  The 
power thus generated was used to auto-park the disk heads.  As least that's 
how I heard it...

I am thinking of old Seagate drives like this one:

http://redhill.net.au/d/5.php


-- 

numerist at aquaporin4 dot com

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#155082

On 2015-12-11, Charles Richmond <numerist@aquaporin4.com> wrote:

> With some of the early Winchester disk drives, when shutting down the 
> computer... one needed to run a "parking" program that unloaded the disk 
> heads and moved them over a "landing zone".  Later drives were 
> "self-parking";  when the power was removed from the drive, the spin-down 
> inertia of the platters made use of the drive motor as a generator.  The 
> power thus generated was used to auto-park the disk heads.  As least that's 
> how I heard it...

That makes sense.  Some of the pre-Winchester drives I saw had a huge
electrolytic capacitor whose purpose was to hold enough charge to yank
the heads off the pack in the event of a power failure (or just do it
fast enough to need more current than the power supply could provide).
A CE once told me about a shop where someone installed said capacitor
backwards.  Upon switching on the power there was a hum which became
louder and louder, then turned into a squeal which was followed by a
spectacular explosion, spraying electrolyte everywhere.

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#155069

"Michael Black" <et472@ncf.ca> wrote in message 
news:alpine.LNX.2.02.1512102259410.27954@darkstar.example.org...
> On Thu, 10 Dec 2015, gareth wrote:
>
>> "Scott Lurndal" <scott@slp53.sl.home> wrote in message
>> news:m9kay.15466$qz7.15339@fx01.iad...
>>> hancock4@bbs.cpcn.com writes:
>>>> Sylvania ran an ad for its LED back in 1957, called a photo diode.
>>>> It was in C&A 09-1957, pg 19.
>>>
>>> Photo-diode != LED
>>
>> Except that most LEDs are reciprocal to light of the same frequency.
>>
> But does that work both ways?
>
> I know people have seen problems with semiconductor diodes that pick up 
> light from a nearby lightbulb.  And certainly you can use an LED as a 
> receiver of light, though I suspect it's not too efficient.
>
> But can you put light through a diode not intended to generate light, and 
> get light?
>

Michael, put any diode you want reverse-biased across a high voltage 
source... and you'll get a bright flash of light.  But only once.

-- 

numerist at aquaporin4 dot com

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#155144

On Thursday, December 10, 2015 at 8:57:47 PM UTC-7, Michael Black wrote:

> But can you put light through a diode not intended to generate light, and 
> get light?

Not counting the destructive mode frequently cited in replies, it may be noted 
that selenium and cadmium sulfide photocells usually exhibited a change in 
resistance due to light, and so one had to run current through them to sense 
light - and generating light wasn't related to the mode of sensing light.

Of course, those photocells aren't photodiodes.

I had to look up a photodiode to be sure what it was. It turns out that 
photodiodes were basically solar cells. However, to be more effective as light 
detectors, instead of waiting until they were hit by enough light to generate a 
detectable signal, they were usually run in a reverse-biased mode.

John Savard

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#154991

hancock4@bbs.cpcn.com writes:

> Sylvania ran an ad for its LED back in 1957, called a photo diode.
> It was in C&A 09-1957, pg 19.
>
> specs:
>
> TABLE OF RATINGS & CHARACTERISTICS
> Absolute Maximum Ratings (at 25°C):
> Operating ,Voltage * * * * * * * * * * * * * 50 volts dc
> Ambient Temperature (Maximum) ****** 75°C
> Power Dissipation ** << * * * * * * * * * * 40 Milliwatts
> Forward Current * * * * * * * * * * * * * 10 Ma dc
> CHARACTERISTICS 1
> Reverse Current--Dark (ER= -10 volts} *** 15 ua max. I
> Reverse Current-Dark (ER= -50 volts) *** 100 UI max. j
> Noise Voltage--Dark (ER>;= -45 volts, , ~'
> Rl=lOO,OOO ohms) * 15 Millivolts max. '
> light Sensitivity ******** 18.7 peak.to·peak,volts-min:
> light Sensitivity. * * * * * ** 37.5 peak.lo-peak volts-max.
> Typical Minimum Frequency Response. * * .,15.0 KC
>
>

That's not an LED, it's a photodiode.

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