oldest semiconductors still in use

George Herold Inscribed thus:

Hi George, I've got it in my head that the 1N34 was silicon ?

to

Well I'll let you know as soon as I test some, Here's the first hit on google,

George H.

cheers Mark

On a sunny day (Thu, 6 Jan 2011 06:51:04 -0800 (PST)) it happened Mark wrote in :

Nice.

On a sunny day (Thu, 6 Jan 2011 06:51:04 -0800 (PST)) it happened Mark wrote in :

Here is some antique radiation meter, that was actually still sort of working, except the HV diode stick was defective, so voltage was low. Note how it is build and note the OC140 glass transistor: ftp://panteltje.com/pub/FT40/PCB_sandwich_img_2392.jpg

Must have cost a fortune to build one this way, PCB? Never heard of!: ftp://panteltje.com/pub/FT40/PCB_sandwich_img_2392.jpg

Diagram: ftp://panteltje.com/pub/FT40/FT40_diagram_img_2385.jpg

These pictures were for my own documentation, before I took it apart, and used some of the parts to make a new modern one:

I have an even older one, using a similar transistor, and a 1.5V dual triode tube. but that one is still working OK. Ge transistors last forever it seems.

That was the 1N60.

interesting.

Are there any modern drop in replacements for stuff like you'd use in a crystal radio?

Or, if I were to take apart a modern communications satellite, would I be able to make the most simple AM receiver possible?

George Herold Inscribed thus:

Thanks George, The mind plays tricks with memories.

Michael A. Terrell Inscribed thus:

I don't recall that one at all. Thanks anyway.

I've got a "crystal set" radio from the 1920s that had a galena catswhisker detector diode. You can still buy galena detectors and somebody has to make them, so that is production.

Before you go off telling me that a catswhisker detector isn't a "semiconductor" do a little research on how schottky diodes are made.

Jim

The pictured part appears to have been made by Newmarket in the UK, a company that went out of business some decades ago.

RL

Galena detectors, ca 1901, probably win, and are sort of still in production. The silicon diode dates to 1903. Copper oxide rectifiers were invented in 1927, seleniums in 1933. You can still buy new-production selenium rectifiers.

Yikes, silicon diodes are over 100 years old!

John

The subject line made me think of semis that are still in operating equipment. A couple years ago, some guys at our university resurrected a LINC computer made at an MIT summer school in 1965. This was a 12-bit computer with 2K words of core memory and little tiny 3/4" tape drives. keyboard input, display on a Tektronix X-Y oscilloscope. Basically, they reported that after rebuilding the main power supply with new filter caps, and reseating a few boards, the machine came up perfectly. so, that was some 43+ years. All discrete transistors, I'm wanting to guess Germanium, but can't say for sure.

I know there is at least one Bendix G-15 computer that is supposed to be semi-operational at the Australian Computer Museum. This was a vacuum-tube machine, but had about 3000 Germanium diodes to form the gates. Drum memory, serial arithmetic, VERRRRY slow! they made them starting in 1955.

Jon

Yep, you win. Runner-up would be some kinds of phototube (the 'semiconductor' would be the cathode material). Plumbicons and vidicons, for example, all use semiconductors in the sensing layer.

As for the '1Nxxx' parts, those all are specified so loosely that they could be reengineered and NO ONE WOULD KNOW. Motorola, for instance, made a 2N3055A with better specs than the 2N3055; most folk just used 'em interchangeably.

And Fairchild made an epitaxial 2N3055 that blew up at a fraction of the SOAR loading of the RCA diffused parts.

John

It's a close replacement for the fried one in Aunt Sally's ancient TV. Using a better rectifier might destroy the equally ancient filter caps, by putting on too much voltage.

(Folks who actually know what the circuitry in the HV section of a tube TV looked like are welcome to correct me.)

Cheers

Phil Hobbs

After you leave the room to avoid an earlier-than-necessary demise. Toasted seleniums are *toxic*.

Cheers

Phil Hobbs

But nobody makes them anymore...like their "audio" cousin, the 2N109. I remember AM radio circuits that used a 2N107 as an oscillator/mixer, another one as the IF amp, and probably 3 2N109s as detector/audio amps.

Cheers

Phil Hobbs