Date   

Re: tunnel diodes retrace lines in curve tracer

Brad Thompson
 

Dennis Tillman W7pF wrote on 2/18/2021 7:14 PM:

Hi Rik,

Tunnel (Esaki) diodes rely on quantum tunneling.
<snip>

Hello--

Does anyone recall "Laugh In" (a satirical TV series of the 1960s which
featured certain repetitive routines-- one called "sock it to me" in particular).

I give you the following: "It may be a tunnel diode to you, but it's an Esaki to me...Esaki to me...."

<grin>

73--

Brad  AA1IP


Re: Shipped They Are

-
 

Mine haven't arrived yet and I'm starting to feel left out!

Dash -

On Thu, Feb 18, 2021 at 8:37 PM Mac Perkins <macp@whidbey.com> wrote:

My boards arrived yesterday. They look great. Many thanks to Jared for
the design and layout and to Larry for making the group buy happen and
distributing all the sets. Started assembling only to find one of the
switches was backordered. On to metalwork for the front panel.

-Mac






Re: Stan Griffiths estate sale

Ryan Scott
 

Greetings all,
Thanks for the kind Comments Dennis.
Tom Kelly and myself went over to Stan's last night and were with about 7 other people who were there.  
I think Valerie and Paul want to keep it small due to Covid.  Plus, I get the feeling they are a bit overwhelmed, which is understandable given Stan's impressive shop and collection.  But I'm glad they are doing something.  Valerie mentioned it was the right thing to do for her Dad.
Stan's shop is pretty much the same as it was the last time myself and a few others were at the weekend sales (Jan 2020) run by a family friend (Bryce I think).  
Several of the 500 series scopes are still there, as well as plug ins.  Note, assume that tubes were pulled from all items remaining as that is what we found with what we took home.  The tube thieves struck early unfortunately.   Lot's of parts / pieces, etc.  
Valerie is very reasonable on the prices of the stuff remaining.  I think I filled my pickup for my initial offer to Valerie of $400 and she said she was thinking $250, so we settled on $350.  Tom's experience was similar.
Ultimately, I get the feeling that she wants to have her Dad's stuff end up in the hands of people like us to keep the love of Tek going.  
The next sale is Saturday, but I am not sure of the time.  Valerie is insistent that it does not become a 'super spreader event' so is keeping it small.  
All sales appointments are being handled by Valerie's friend, Paul, who is also a good guy.  But he's surprised and overwhelmed at the response thus far.
Interested parties can reach Paul via Next door, or Facebook, as per his initial ad.  (Not the ideal form of communication, but he does respond)
As far as the deadline of end of next week, it appears that Valerie may have received an extension.  
Tom, Tim Pierce, and Myself all agreed we will do whatever we can to save the stuff from the scrappers.  We are just waiting to hear from Valerie, and we did let her know we would surely help when the time came.  
I'll post more probably after this weekend.  
Thanks and Regards,Ryan Scott

On Thursday, February 18, 2021, 11:47:21 AM PST, n4buq <n4buq@knology.net> wrote:

Okay, Walter, thanks for that info.  I think I looked up what I could find on those model numbers back then and I don't remember whether I found that was an indication or not.  Good to know.

This is for a Hameg scope which apparently uses the same CRT.  I'll contact you off-list for more details.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "walter shawlee" <walter2@sphere.bc.ca>
To: TekScopes@groups.io
Sent: Thursday, February 18, 2021 1:17:59 PM
Subject: Re: [TekScopes] Stan Griffiths estate sale

Barry, the /123 means it has a graticule in the CRT part number. These are
all for Philips scopes.

regards,
walter.






Re: Semtech HV multipliers + more....

n4buq
 

Hi Walter,

Did you receive my direct email today regarding the CRT from the Stuff page?

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "walter shawlee" <walter2@sphere.bc.ca>
To: TekScopes@groups.io
Sent: Thursday, February 18, 2021 6:58:47 PM
Subject: [TekScopes] Semtech HV multipliers + more....

I noticed we had a bunch of these new military HV multiplier assemblies, They
may prove useful for fixing
one that has tanked in your scope. the part number is SCMA 10139, and they
are at the end of this stuff section:
https://www.sphere.bc.ca/test/stuffday.html#power2

Sorry, I don't have any specs, and my goog-fu was not able to turn anything
up even with the federal stock number.
Maybe Dennis can do a better job. Judging by the size, it would have thought
at least 4-5X.
Hopefully they may be useful to somebody.

I am starting to fill up the Tektronix portion of the page, and there's some
very sexy items in there today. My thanks to my son for the incredible
number of hours he has spent photographing all the items. Now you can really
see what everything looks like.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.






Re: Shipped They Are

Mac Perkins
 

My boards arrived yesterday. They look great. Many thanks to Jared for the design and layout and to Larry for making the group buy happen and distributing all the sets. Started assembling only to find one of the switches was backordered. On to metalwork for the front panel.

-Mac


Re: Semtech HV multipliers + more....

-
 

Walter,

I can tell you that it's made by General Electric.

On Thu, Feb 18, 2021 at 7:59 PM walter shawlee <walter2@sphere.bc.ca> wrote:

I noticed we had a bunch of these new military HV multiplier assemblies,
They may prove useful for fixing
one that has tanked in your scope. the part number is SCMA 10139, and they
are at the end of this stuff section:
https://www.sphere.bc.ca/test/stuffday.html#power2

Sorry, I don't have any specs, and my goog-fu was not able to turn
anything up even with the federal stock number.
Maybe Dennis can do a better job. Judging by the size, it would have
thought at least 4-5X.
Hopefully they may be useful to somebody.

I am starting to fill up the Tektronix portion of the page, and there's
some very sexy items in there today. My thanks to my son for the incredible
number of hours he has spent photographing all the items. Now you can
really see what everything looks like.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.






Semtech HV multipliers + more....

 

I noticed we had a bunch of these new military HV multiplier assemblies, They may prove useful for fixing
one that has tanked in your scope. the part number is SCMA 10139, and they are at the end of this stuff section: https://www.sphere.bc.ca/test/stuffday.html#power2

Sorry, I don't have any specs, and my goog-fu was not able to turn anything up even with the federal stock number.
Maybe Dennis can do a better job. Judging by the size, it would have thought at least 4-5X.
Hopefully they may be useful to somebody.

I am starting to fill up the Tektronix portion of the page, and there's some very sexy items in there today. My thanks to my son for the incredible number of hours he has spent photographing all the items. Now you can really see what everything looks like.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.


Re: Cleaning Scratchy Bourns MOD pots

Renée
 

Check at the hobby shops especially train and plane builders....I have obtained brass ones
Renée

On 2/18/21 4:06 PM, - wrote:
Dennis,

Skycraft surplus store in Orlando has 2-56 and smaller screws. They
even have 0-80 screws in there. IIRC the price was about 10c each.

On Thu, Feb 18, 2021 at 7:01 PM Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi Ed,
I never thought about suction until you just mentioned it just now. Thank
you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch
assembly in cleaning solution in an ultrasonic cleaner. My hope was the
ultrasonic bursting bubbles would be able to get some solution into the
wipers through the shafts. I left the dual-pot/pull-switch assembly in the
ultrasonic cleaner for a few hours to give it every chance to succeed. It
had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure
nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was
a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at
very reasonable prices ($7 for 25 screws). There are even longer ones but
they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one
that controls the output level and DC offset of an otherwise pristine late
model FG 501A function generator. This is a very impressive plugin capable
of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like
to be able to adjust the DC offset (which goes from +15V to -15V) so I
could set the square wave output to go from 0V to +30V into 50 ohms. That
is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very
difficult time getting it all back together. Do you think I would be able
to get cleaning solution into the assembly if I drilled out two of the
rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out
one rivet at a time and replace it with a screw loosely tightened on the
assembly. Once all 4 rivets were replaced with loosely tightened screws
this way there should be sufficient room for cleaning solution to get in
without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have
done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Thank you Ed!!!

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed
Breya via groups.io
Sent: Monday, February 15, 2021 8:06 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

A safer approach may be the more drastic measure of drilling out the
rivets, then you can take it apart for full access. You can replace the
rivets with long screws, about 2-56 here, or metric equivalent. I think
these and the Allen-Bradley mod-pots (that are screwed together) have been
discussed recently too. I just restored a single section A-B one recently -
a bad level control on a Wavetek 3000, that was totally intermittent. I
figured I could do it without unhooking from the wires, just long enough to
get the pot accessible. I managed to get it apart and hit it with D100,
right from the back of the rotor, which is the closest access to the
resistance element. It went back together OK, but took quite a few
rotations before it cleaned up and smoothed out. If you try to just spray
cleaners from the outside or shaft bushing, it's a long trip to expect
anything to soak in and reach the wiper and element. So, drilling a
strategically located access hole, or disassembly are the "simple" ways to
go. I think I've mentioned vacuum methods here too, recently, where you put
suction on the pot and use that in various ways to pull lots of cleaner
inside.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator







Re: tunnel diodes retrace lines in curve tracer

 

Hi Rik,

Tunnel (Esaki) diodes rely on quantum tunneling. That is probably beyond the expertise of most electronics engineers to model in the way I think you mean. On the other hand it is not that hard to come up with a polynomial equation that models the shape of the I/V curve of the tunnel diode. I have done this myself. Excel can even automatically calculate a halfway decent polynomial from a spreadsheet you fill with about 20 or 30 I versus V points you plot off of a curve tracer. A really good curve fit requires about 12 or 13 polynomial terms.

The answer to your 2nd question has a lot to do with biasing. With only two leads you are stuck with very simple biasing schemes and options. That severely limits what you can do with a Tunnel Diode and achieve CONSISTENT results. Without consistency it is hard to make reliable products.
When they were first developed their simplicity and their speed were seen as big plusses. When it turned out that simplicity and consistency were not compatible that left their speed as their most interesting features. Gradually over time the semiconductor industry has learned how to make faster and faster semiconductors and that makes TDs less valuable as a circuit component.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of garp66
Sent: Thursday, February 18, 2021 10:59 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] tunnel diodes retrace lines in curve tracer


OT: Fig. 1 of the Tektronix Jack Rogers doc....

Tunnel Diodes and the stock market ??
{ apologies ... really }

I was looking at Fig. 1 in the Jack Rogers doc that Dennis graciously posted,

.. and was immediately struck, ...had just been doing an introductory "Stock Market 101 tutorial" for dummies, the other day,
simply because I know nothing about the market.

The first graph discussed in that SM 101 tutorial was called a "cup and handle" which sort-of looks like the TD Fig.1, in the Rogers Tek doc,
- but the SM graph is reversed along the horizontal axis, compared to the TD graph.

Which brings me to a question that must be obvious, and studied:
-- Have TD's been modelled mathematically in efforts to better understand TD's non-linear behaviour and to produce better units ?
Presumably there are (many ?) EE theses in this area.
and
-- Why have TD's become less of a produced and explored area of semiconductors ?
Is there something that better replaces them now ?

Rik







--
Dennis Tillman W7pF
TekScopes Moderator


Re: Cleaning Scratchy Bourns MOD pots

-
 

Dennis,

Skycraft surplus store in Orlando has 2-56 and smaller screws. They
even have 0-80 screws in there. IIRC the price was about 10c each.

On Thu, Feb 18, 2021 at 7:01 PM Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi Ed,
I never thought about suction until you just mentioned it just now. Thank
you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch
assembly in cleaning solution in an ultrasonic cleaner. My hope was the
ultrasonic bursting bubbles would be able to get some solution into the
wipers through the shafts. I left the dual-pot/pull-switch assembly in the
ultrasonic cleaner for a few hours to give it every chance to succeed. It
had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure
nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was
a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at
very reasonable prices ($7 for 25 screws). There are even longer ones but
they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one
that controls the output level and DC offset of an otherwise pristine late
model FG 501A function generator. This is a very impressive plugin capable
of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like
to be able to adjust the DC offset (which goes from +15V to -15V) so I
could set the square wave output to go from 0V to +30V into 50 ohms. That
is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very
difficult time getting it all back together. Do you think I would be able
to get cleaning solution into the assembly if I drilled out two of the
rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out
one rivet at a time and replace it with a screw loosely tightened on the
assembly. Once all 4 rivets were replaced with loosely tightened screws
this way there should be sufficient room for cleaning solution to get in
without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have
done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Thank you Ed!!!

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed
Breya via groups.io
Sent: Monday, February 15, 2021 8:06 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

A safer approach may be the more drastic measure of drilling out the
rivets, then you can take it apart for full access. You can replace the
rivets with long screws, about 2-56 here, or metric equivalent. I think
these and the Allen-Bradley mod-pots (that are screwed together) have been
discussed recently too. I just restored a single section A-B one recently -
a bad level control on a Wavetek 3000, that was totally intermittent. I
figured I could do it without unhooking from the wires, just long enough to
get the pot accessible. I managed to get it apart and hit it with D100,
right from the back of the rotor, which is the closest access to the
resistance element. It went back together OK, but took quite a few
rotations before it cleaned up and smoothed out. If you try to just spray
cleaners from the outside or shaft bushing, it's a long trip to expect
anything to soak in and reach the wiper and element. So, drilling a
strategically located access hole, or disassembly are the "simple" ways to
go. I think I've mentioned vacuum methods here too, recently, where you put
suction on the pot and use that in various ways to pull lots of cleaner
inside.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator






Re: Cleaning Scratchy Bourns MOD pots

 

Hi Ed,
I never thought about suction until you just mentioned it just now. Thank you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch assembly in cleaning solution in an ultrasonic cleaner. My hope was the ultrasonic bursting bubbles would be able to get some solution into the wipers through the shafts. I left the dual-pot/pull-switch assembly in the ultrasonic cleaner for a few hours to give it every chance to succeed. It had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at very reasonable prices ($7 for 25 screws). There are even longer ones but they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one that controls the output level and DC offset of an otherwise pristine late model FG 501A function generator. This is a very impressive plugin capable of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like to be able to adjust the DC offset (which goes from +15V to -15V) so I could set the square wave output to go from 0V to +30V into 50 ohms. That is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very difficult time getting it all back together. Do you think I would be able to get cleaning solution into the assembly if I drilled out two of the rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out one rivet at a time and replace it with a screw loosely tightened on the assembly. Once all 4 rivets were replaced with loosely tightened screws this way there should be sufficient room for cleaning solution to get in without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Thank you Ed!!!

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via groups.io
Sent: Monday, February 15, 2021 8:06 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

A safer approach may be the more drastic measure of drilling out the rivets, then you can take it apart for full access. You can replace the rivets with long screws, about 2-56 here, or metric equivalent. I think these and the Allen-Bradley mod-pots (that are screwed together) have been discussed recently too. I just restored a single section A-B one recently - a bad level control on a Wavetek 3000, that was totally intermittent. I figured I could do it without unhooking from the wires, just long enough to get the pot accessible. I managed to get it apart and hit it with D100, right from the back of the rotor, which is the closest access to the resistance element. It went back together OK, but took quite a few rotations before it cleaned up and smoothed out. If you try to just spray cleaners from the outside or shaft bushing, it's a long trip to expect anything to soak in and reach the wiper and element. So, drilling a strategically located access hole, or disassembly are the "simple" ways to go. I think I've mentioned vacuum methods here too, recently, where you put suction on the pot and use that in various ways to pull lots of cleaner inside.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator


Re: tunnel diodes retrace lines in curve tracer

 

Hi Brad,
RCA made them. They came in a 1" wide stud mounted case. The stud's threads were 3/8" - 24.
The RCA 40079 had an Ip of 180 to 220 AMPS!
The RCA 40070 was rated at 90 to 110 AMPS Ip.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Brad Thompson
Sent: Thursday, February 18, 2021 2:22 PM

I dimly recall a mention of 100-ampere tunnel diodes, likely lab curiosities that never saw production in any meaningful quantities. One possible application might have served as switches in a DC-to-DC convertor fed by power from low-voltage sources (thermopiles?).

73--

Brad AA1IP







--
Dennis Tillman W7pF
TekScopes Moderator


Re: Failed Transistor with Low h(FE)?

 

Hi Jeff,
Transistors do not have a "specific" hFE. Look at the datasheets for the 2N3565 and the 2N2907 transistors. For that matter, you can look at the datasheet for ANY transistors. The datasheets always show a Min(imum), Nom(inal), and Max(imum), or at least two of these three values, for the transistor's hFE.

If you look a little closer at a transistor datasheet you will notice that those Min / Non / Max values are specified at a SPECIFIC collector current. The reason manufacturers specify the collector current they measured the hFE at is because the hFE can vary widely as the collector current is changed. They may also specify the temperature because hFE varies as the temperature of the transistor changes. Unless otherwise noted the temperature is usually room temperature (25C).

Circuit Design Engineers know all of this so they never design a circuit using the manufacturer's maximum hFE figures because there is always the chance they will turn out to be 1/5th of that value under actual operating conditions. Instead they use many different forms of feedback to insure the circuit is not dependent on a transistor's hFE, but on other more stable circuit components.

When you see an hFE over 100 in most cases it no longer matters whether it is 200, or 400, or 600. An hFE over 100 is excellent and no designer would design this circuit assuming all the transistors would have an hFE of at 400. The ONLY EXCEPTION is when transistors have to be hand selected to meet some specific criteria that a circuit requires.

The Fairchild 2N3565 datasheet specifies hFE as 120 min to 600 max. I will bet the circuit they are in will work just fine with any transistor with an hFE over 50.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky
Sent: Thursday, February 18, 2021 7:57 AM
To: TekScopes@groups.io
Subject: [TekScopes] Failed Transistor with Low h(FE)?

I'm trying to fix a DM501 that I damaged by plugging it into a faulty backplane. One of the display digits is stuck on and I think that I've narrowed the cause down to one of two transistors that drives the display chip select lines (Q348 or Q350). I removed both transistors, but when I checked them in my component tester neither one looks "blown". Q348 however (a 2N3565) has a lower hFE than the replacements I have in hand.

Here are the measured hFE for the suspect and replacement parts:

old 2N3565 (Q348): hFE=287, Vf=683
old 2N2907 (Q350): hFE=227, Vf=667

new 2N3565 (two tested): hFE=(443, 343), Vf=(673, 645) new 2N2907 (one tested): hFE=288, Vf=673

I was expected to find the failed part as a short or open. Could a failed transistor simply have a decreased gain?

-- Jeff Dutky







--
Dennis Tillman W7pF
TekScopes Moderator


Re: Failed Transistor with Low h(FE)?

Ozan
 

I did not have an extender until a few days ago, and had not checked any
electrical signals in operation. I will do that now.
Got it, it is one of those units that need an extender to probe inside.


It also occurred to me that I can swap the pins going to the display board and
see if the malfunction follows the pin swap (this would rule out the display
element).
When you removed Q350 if the problematic digit turned off, it says only path is through Q350. As an interesting experiment you can try putting the decimal point on the problematic segment by changing scale (i.e. close S10-36) and check if decimal point shows up in all segments. If it does pin 17 is stuck high.

Ozan


Re: tunnel diodes retrace lines in curve tracer

Chuck Harris <cfharris@...>
 

Some of the paper abstracts I have seen when searching tunnel diodes
seem to imply that they are being used in solar arrays for switching.

-Chuck Harris

Brad Thompson wrote:
...

I dimly recall a mention of 100-ampere tunnel diodes, likely lab curiosities
that never saw production in any meaningful quantities. One possible
application might have served as switches in a DC-to-DC convertor fed
by power from low-voltage sources (thermopiles?).

73--

Brad  AA1IP






Re: Help replacing a resistor/inductor in SG503

 

Roy,

The Z-axis amp fix worked out quite well. I did NOT end up replacing the two CC resistors standing on end, not least because it was too difficult to get a soldering iron in between the bottom ends of the resistors and the pads they are soldered to (also because I was assured, and if performance is any indicator the assurances were correct, that the specific value of those resistors was not vital the circuit).

-- Jeff Dutky


Re: 93 Ohm feed-thru terminators - Unobtanium? No, as it turns out.

leonard scheepsma
 

So I have 3 of them in the mail right now, an excellent result with many thanks to Walter. So still one failing in my double terminated set-up. Anyone with 1 or 2 in a drawer somewhere?

Thanks again, Leonard


Re: tunnel diodes retrace lines in curve tracer

Jeff Kruth
 

I spoke with EE's involved with tunnel diode in the early 60's.They told me of their struggles. TD's were going to be the great savior... except that is was hard to make a run of them that had consistent characteristics! The mix was variable...  Somewere used for low level microwave oscillators, I had a few boxes from NSA that used them as check sources.  Narrow band amplifiers were popular in the microwave world using circulators as signal separation devices, I have an Aertech 8.6-9.4 GHz Tunnel Diode Amplifier box. Even some high speed gates were made. Just couldnt make enough the same to do large volume production. The tunnel diode, or IIRC the Esaki diode, was largely a curiosity. Good I guess in some Tek circuits, but even they struggled, I think, to get consistency. I think I have some Tektronix "Diode Rise Time Fixtures" around that Tek made for testing and sorting diodes like this.

Jeff KruthIn a message dated 2/18/2021 4:55:02 PM Eastern Standard Time, saipan1959@gmail.com writes: My understanding is that by the 1970's or so, TD's were obsolete because most of the practical circuits that used them could be done cheaper with modern transistors and IC's.
TD's could do certain things with a bare minimum parts count, but that wasn't important enough, with the parts count (inside of IC's) exploding in other areas.
Also note that many of the interesting apps for TD's involve inductors, but inductors are not cheap.

I could be wrong...

Pete


Re: tunnel diodes retrace lines in curve tracer

Jim Ford
 

Hmmm... Might there be a way to combine the TD and the transistor?
Something compatible with the ginormous silicon CMOS infrastructure already in place? I no longer work for a semiconductor shop, so I don't have access to the brainpower there anymore, but people on this group must. Put your thinking caps on....

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: TekScopes@groups.io
Sent: 2/18/2021 2:14:43 PM
Subject: Re: [TekScopes] tunnel diodes retrace lines in curve tracer

Tunnel diodes excited a lot of interest for about a decade after their commercial introduction. In fact, TDs and the first IC from Fairchild (a four-transistor flip-flop) competed for attention at what is now the ISSCC conference, in 1961. The press largely ignored the IC. Articles from that time were obsessed with the tunnel diode instead. The future was going to be powered by TDs. Supercomputers, satellites, Dick Tracy wristwatch TVs...all were Coming Real Soon (tm), thanks to TDs. Then reality hit: Yes, they were much faster than contemporary transistors, but they were two-terminal devices. Making a chain of amplifiers was difficult because a change in load /here/, rippled all the way back to the input /there/. The same problem afflicted networks of logic gates. So scaling up to large systems seemed unlikely. Various desperate, complicated arrangements were devised in an effort to fix that and other practical problems, but the added complexity nullified the putative advantages of the TD. After a few turns of the Moore's law crank, it was clear that the IC was the future, and the TD gradually became the answer only to trivia questions.

--Tom

-- Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 2/18/2021 13:54, saipan59 (Pete) wrote:
My understanding is that by the 1970's or so, TD's were obsolete because most of the practical circuits that used them could be done cheaper with modern transistors and IC's.
TD's could do certain things with a bare minimum parts count, but that wasn't important enough, with the parts count (inside of IC's) exploding in other areas.
Also note that many of the interesting apps for TD's involve inductors, but inductors are not cheap.

I could be wrong...

Pete









Re: tunnel diodes retrace lines in curve tracer

Brad Thompson
 

Tom Lee wrote on 2/18/2021 5:15 PM:

(And yes, I know that we already had satellites by 1961. But not powered by TDs)
Hello,  Tom and the group--

I dimly recall a mention of 100-ampere tunnel diodes, likely lab curiosities
that never saw production in any meaningful quantities. One possible
application might have served as switches in a DC-to-DC convertor fed
by power from low-voltage sources (thermopiles?).

73--

Brad  AA1IP

4721 - 4740 of 183422