On Friday 29 November 2024 07:24:12 pm wn4isx via groups.io wrote:

This will be my last post on non-LED semiconductors emitting light.

First, all of the forward biased semiconductors I tested emitted light. The glass cased silicon diodes were the easiest to verify, I chopped the tops of several TO-3 and TO-5 transistors. All of the emitted light required a night vision (starlight) scope to see. 4th vision nightvision scopes have between 25,000-110,000 gain, the exact gain figures are apparantly restricted by ITAR [International Traffic in Arms Regulations].

However reverse biased semiconductor junctions are a different story. I'll admit I was pleasantly surprised....

A friend gave me this link. Interesting to be sure but I doubt it's practical.



And it might be worthwhile to follow the links here



This image is fascinating and I was able to come very close image with a 1980s 2N2222 with the top removed.



This light is clearly visible in a dark room.

I sacrificed 3 2N3055s. These were older RCA units with excessive leakage.

All 3 emitted nice light when the collector to base junction was reverse biased to break down.

Note: Limit breakdown current to a few mA.

This has been an interesting, if relatively useless experiment.

I remember bumping into something weird in certain Yamaha power amplifiers. They used an actual LED as a biasing part. Though this was not in the typical LED case, but more like the sort of glass-bodied case you'd see for a 1N400x rectifier or similar. I'm not sure why they chose this part, not having actually sat and analyzed the circuit, maybe temperature coefficient or something?

I know that there were a whole lot of power amps out there that when one output device failed, the rest of them, along with the drivers, and someimes a whole lot more would also fail. This was not the case with those Yamaha amps, you'd blow one device that that was the extent of the failure, pretty solid stuff that was.

Another thing that comes to mind is a thing that Forest Mims did one time. He had two LEDs facing each other, and the one that lit would cause the other one to act as a photodiode.

I have some radio shack packages with "IR emitter-detector pair" in them, and an assortment of phototransistors pulled from scrapping VCRS (there's at least two in every VHS machine) and some other parts salvaged from floppy drives, where they are used for write protect and index hole sensing. I haven't found any particular use for these parts, maybe I just haven't found the right inspiration yet...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Saturday 30 November 2024 03:51:56 pm Roy J. Tellason, Sr. via groups.io wrote:

I have some radio shack packages with "IR emitter-detector pair" in them, ?and an assortment of phototransistors pulled from scrapping VCRS (there's at least two in every VHS machine) and some other parts salvaged from floppy drives, ?where they are used for write protect and index hole sensing. ?I haven't found any particular use for these parts, ?maybe I just haven't found the right inspiration yet...

Oh yeah, and optoisolators and optointerrupters. I have a whole tube of NOS 4N26, I think, plus piles of salvaged other numbers I did find a use for an optointerrupter. I was given a sewing machine motor, plugged it in and spitzensparken! So I disassembled it and replaced the cord. Then with it spinning I wondered how fast that thing was going. So I rigged up an optointerrupter on a bit of perfboard, put a bit of tape on the motor shaft, and coupled the output to my scope. It was a surprisingly high number as I recall, though of course there was no load on the motor...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Sunday 01 December 2024 09:50:58 am wn4isx via groups.io wrote:

Here is a link to Mr. Mimms own words detailing his fight with AT&T over breach of contract using LEDs as transmitter and optical receiver. It is amazing because the little guy almost never wins.

The excerpt from the book linked on that page goes into a bit more detail:



It's about 13 pages.

Compare to the poor sod who patented the slow kick wiper then spent half a lifetime fighting Ford.

Heh. I don't recall seeing plans for such a thing in any of the magazines, though I suppose that it's possible. I built one in a minibox that bolted to the underside of the dash in a 1970 Dodge Dart. It used a 555 and a relay.

(...)

I know I build one for my father's car in the summer of 1968, I think the plans were in either Popular Electronics or Radio Electronics. He owned Dodge/Chrysler and required some intensive modification to the wiring because the wipers didn't just stop, they reversed and nestled down hidden out of the way.

Some of those setups are just weird. Mine was fairly straightforward.

I made one for my older sister's Chevy, easy peasy, large assed SCR, unijunction and she was ready to hit the road.

That does sound better than a relay.

And another "We stole your idea now bug off and leave us alone."


The moral is, if you come up with a wonderful idea, good luck not getting ripped off, might as well make it public domain to at least screw the big boys.

Yup! Just put it out there...

You Linux guys are lucky SCO lost....
" The software ( ) company SCO Group ( ) (SCO), formerly Caldera International ( ) , asserted in 2003 that it was the owner of Unix, and that other Unix-type operating systems—particularly the free ( ) operating system Linux ( ) and other variants of Unix sold by competitor companies—were violating their intellectual property by using Unix code without a license in their works"

That whole thing was such a joke!

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Sunday 01 December 2024 01:27:33 pm wn4isx via groups.io wrote:

BTW I strongly suggest not duplicating my mistake.

Not sure why anybody would want to...

Besides wasting 4 perfectly good, and rare, diodes,

Rare? I'd call the 1N400x parts exceedingly common. And regarding ordering them, if I were to do so I'd go for the max voltage ones, the difference in price is not worth worrying about if you're not a mfr. I do have an assortment of these in salvaged parts, but don't see me using them for much, maybe a 1N4001 would be useful across a relay coil or similar application.

(...)

I only have 6 working glass body GE tunnel diodes, they are rare enough that I was unwilling to test them as they are 60 years old and were rather delicate when new,

The only ones I've run across were in metal cases.

I'm tempted to order some Soviet/Russian tunnel diodes from E-Flea and check them.

Funny how those were put out there, showed up in the magazine articles etc. and then seemed to go away. The only place I've ever heard of them being used was in certain Tek scopes, and I've not looked into how they were used there. Ages ago (say early 1970s) there were a bunch of interesting shops on Canal Street in NYC, I guess the last gasp of "Radio Row" (see wikipedia on that). One place did sell tunnel diodes, and I have a vague recollection of a bit of perfboard, some resistors and a trimpot and one of those parts, but I don't recall ever getting around to hooking up a tuned circuit to it to see if it would oscillate. I do have one of those parts in my box of diodes, but am not sure about it, and will have to put it on my curve tracer to see what it does.

The reverse bias photon emission was bright enough to be seen with the naked eye, the effect was quite striking, go to the links I provided for interesting photographs.

I've been given some early glass cased germanium transistors that have cases painted in black.
I'm hoping I can remove the paint without damaging the case. Anyway I think the cases are glass.

An x-acto knife might be just the thing to remove that coating. I don't remember any glass cased stuff like that, though. I did have a "photo transistor" at one point in a TO-3 case (!) where the top of the case was a red lens. Pretty low power handling capability considering the case.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

开云体育

I would dispute the "let's waste money" part - there were a LOT of unknown variables when they started and they learned a LOT of lessons with little loss of life. The lives lost were due to making decisions about variables that they thought they knew about, but which were actually not as well known as believed - Challenger SRB O-rings and retainers; ice damage to thermal tiles; fire hazard of wire insulation in a high-oxygen environment coupled with lack of consideration for rapid module exit requirements.

There was waste, for sure, but I would argue the increase in knowledge far exceeded the dollar cost.

Donald.

On Sunday 01 December 2024 03:27:27 pm Donald H Locker via groups.io wrote:

I would dispute the "let's waste money" part - there were a LOT of unknown variables when they started and they learned a LOT of lessons with little loss of life. The lives lost were due to making decisions about variables that they thought they knew about, but which were actually not as well known as believed - Challenger SRB O-rings and retainers; ice damage to thermal tiles; fire hazard of wire insulation in a high-oxygen environment coupled with lack of consideration for rapid module exit requirements.

There was waste, for sure, but I would argue the increase in knowledge far exceeded the dollar cost.

Donald.

On 12/1/24 14:34, wn4isx via groups.io wrote:

My uncle worked for a company that made sub assembles for NASA and NASA ordered a special run of maybe 1000 1N4004 in glass. They wanted to study what vibration did the the PN junction. It worked out the glass couldn't withstand the g forces of the shake table and failed long before any meaningful data was collected,
My uncle gave them to me. I should have saved them because they'd be collector's items today.

The company made the locking solenoids that held the LEM to the Apollo command module.
I have one of the engineering prototypes made for proof of concept.

So yes 1N4004 diodes are a dime a dozen (or nickle) but the glass envelopes were an odd ball.
NASA did all sorts of similar "Let's waste money." The major companies loved those projects, cost plus were contracts were amazingly profitable.

For some interesting insights into this stuff, they had a publication out called "NASA Tech Briefs", which I subscribed to for a while some years back. It was one of those "free if you qualify" kind of subscriptions...


--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

开云体育

I read many NASA Tech Briefs and used quite a few of the technologies reported therein!

Donald.