John Larkin <jlarkin@highland_atwork_technology.com>: May 21 10:33AM -0700
On Sun, 17 May 2020 14:15:31 -0000 (UTC), Cursitor Doom
>Is it feasible to remove the whiskers by this sort of method or any other?
>Thanks,
>CD
Does anyone still make ge transistors? I can't think of any use for
them.
The only production ge devices I know of (excepting SiGe) are back
diodes, which I think are the only germanium parts fabricated using
lithography.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
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DecadentLinuxUserNumeroUno@decadence.org: May 21 06:09PM
John Larkin <jlarkin@highland_atwork_technology.com> wrote in
>>CD
> Does anyone still make ge transistors? I can't think of any use
> for them.
General Electric? Hehehe.. You mean Ge as in Germanium.
https://spectrum.ieee.org/semiconductors/materials/germanium-can-take-
transistors-where-silicon-cant
> The only production ge devices I know of (excepting SiGe) are back
> diodes, which I think are the only germanium parts fabricated
> using lithography.
https://www.americanradiohistory.com/Archive-Catalogs/GE/GE-Transistor-
Manual-No.-5---1960.CV01.pdf
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Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: May 21 02:12PM -0400
On 2020-05-21 13:33, John Larkin wrote:
> The only production ge devices I know of (excepting SiGe) are back
> diodes, which I think are the only germanium parts fabricated using
> lithography.
Ge makes good photodiodes for some uses. They're very leaky, but if you
make the epi thin enough, they can cover 350-1800 nm, which otherwise
requires expensive stacked-die devices. Garden-variety ones are more
like ordinary InGaAs, i.e. 800-1800 nm, which is much less interesting.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
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DecadentLinuxUserNumeroUno@decadence.org: May 21 06:13PM
John Larkin <jlarkin@highland_atwork_technology.com> wrote in
> The only production ge devices I know of (excepting SiGe) are back
> diodes, which I think are the only germanium parts fabricated
> using lithography.
Also as a side note to the title of this entire thread...
'Vintage transistors' were NOT 'tin plated' like todays parts are.
They were Nickel Cadmium plated. A far superior plating but with
carcinogenic dangers that caused Cadmium and Cadmium alloys to be
banned. But you can still buy, eat and die from Beryllium parts.
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DecadentLinuxUserNumeroUno@decadence.org: May 21 06:16PM
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in
> much less interesting.
> Cheers
> Phil Hobbs
https://iopscience.iop.org/article/10.7567/JJAPS.14S1.57
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John Larkin <jlarkin@highland_atwork_technology.com>: May 21 01:39PM -0700
On Thu, 21 May 2020 14:12:43 -0400, Phil Hobbs
>like ordinary InGaAs, i.e. 800-1800 nm, which is much less interesting.
>Cheers
>Phil Hobbs
Our FLIR has a germanium lens.
https://www.dropbox.com/s/uda77g9w66x3u9f/Flir_E45_WA_Lens.JPG?raw=1
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
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Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: May 21 05:20PM -0400
>> Cheers
>> Phil Hobbs
> https://iopscience.iop.org/article/10.7567/JJAPS.14S1.57
That's a thin-film bolometer, similar in general character to the ones
used in modern uncooled microbolometer cameras. Compared with
visible/NIR photodiodes, they're slow and very insensitive, but they
sure do have a wide wavelength range.
20 years ago I built an interesting system called "Footprints" that I've
discussed here a few times over the years. It used an array of 96
carbon-ink pixels screen-printed on a 9-um thick free-standing film of
PVDF (which is basically fluorinated Saran Wrap). The pixels were 3 x 5
mm on a 6-mm pitch, to leave room for the wiring. The readout
multiplexer was a single red display LED per pixel.
Diodes ideally conduct in only one direction. The particular LEDs I
used leaked less than 50 fA between -5V and +0.5V bias. Interfacing
them to an AC-only sensor such as a pyoelectric requires a bit of bias
current, which in my gizmo was supplied by four green display LEDs,
which allowed the processor to adjust the average bias current between 0
and about 5 pA per LED.
The optical system was a moulded Fresnel lens made out of HDPE
(bleach-bottle plastic).
When it was done, it had very competitive sensitivity: noise equivalent
delta-T of just over 0.1 K, not bad for something so minimalistic.
We tried licensing it, but couldn't because the parts cost was too low.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
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Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: May 21 05:26PM -0400
On 2020-05-21 16:39, John Larkin wrote:
>> Phil Hobbs
> Our FLIR has a germanium lens.
> https://www.dropbox.com/s/uda77g9w66x3u9f/Flir_E45_WA_Lens.JPG?raw=1
Germanium makes really good IR lenses. Besides the built-in filtering
action, it has a refractive index of 4. The optical power of a given
surface is (n-1)/r, where n is the index and r is the radius.
Glass is generally around n = 1.5-1.8, so a Ge lens of a given power has
4-6 times the radius of curvature. Aberrations are much reduced due to
the weaker curvature, so a simpler lens can have better performance.
Also of course the diffraction spot size goes like lambda, so in terms
of the diffraction limit a Ge lens at 10 um is like 100 times easier to
design than a glass lens at 500 nm.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
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Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: May 21 05:29PM -0400
On 2020-05-21 17:26, Phil Hobbs wrote:
> Also of course the diffraction spot size goes like lambda, so in terms
> of the diffraction limit a Ge lens at 10 um is like 100 times easier to
> design than a glass lens at 500 nm.
Oh, and the dispersion of Ge out in the thermal IR is much less than
glass in the visible, so you don't even need to achromatize it. The
tempcos of index and of optical path length are quite large, so you do
need to athermalize in general, something that's rarely required in the
visible.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
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John Larkin <jlarkin@highland_atwork_technology.com>: May 21 02:49PM -0700
On Thu, 21 May 2020 17:26:09 -0400, Phil Hobbs
>design than a glass lens at 500 nm.
>Cheers
>Phil Hobbs
That lens stays in focus up to the point it touches a part. It will
clearly show the hot spot on an 0603 resistor.
Here's a tiny dual transistor,
https://www.dropbox.com/s/dd072w1z2gmfpbt/Dual_NPN.jpg?raw=1
obviously two separate chips inside.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
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