Puzzling diode...

B

Bob Engelhardt

Guest
Just curious - it\'s puzzling, but I have no need for information.

I found these diodes (new) at the dump & I can\'t find anything about
them. I\'ve gone so far as to scroll through 100\'s of Google images.

Anyhow, they\'re marked with a plain diode symbol, but the ID is weird:
\"IC1790\" (not 1N....). There is also \"IN-COM\". They are axial top-hat
package.

The more I looked without finding anything, the more curious that I
became. Any help would be a relief.

Thanks, Bob
 
On 07.04.22 17:13, Bob Engelhardt wrote:
Just curious - it\'s puzzling, but I have no need for information.

I found these diodes (new) at the dump & I can\'t find anything about
them. I\'ve gone so far as to scroll through 100\'s of Google images.

Anyhow, they\'re marked with a plain diode symbol, but the ID is weird:
\"IC1790\" (not 1N....). There is also \"IN-COM\". They are axial top-hat
package.

The more I looked without finding anything, the more curious that I
became. Any help would be a relief.

Thanks, Bob
Click to expand...
One picture is worth a thousand words.
 
On 4/7/2022 11:24 AM, Sjouke Burry wrote:

> One picture is worth a thousand words.

Maybe ... https://imgur.com/PShcDYZ
 
On 4/7/2022 12:26 PM, Bob Engelhardt wrote:
On 4/7/2022 11:24 AM, Sjouke Burry wrote:

One picture is worth a thousand words.

Maybe ... https://imgur.com/PShcDYZ
Click to expand...

The \"brim\" is the cathode.
 
On 07/04/2022 16:13, Bob Engelhardt wrote:
Just curious - it\'s puzzling, but I have no need for information.

I found these diodes (new) at the dump & I can\'t find anything about
them.  I\'ve gone so far as to scroll through 100\'s of Google images.

Anyhow, they\'re marked with a plain diode symbol, but the ID is weird:
\"IC1790\" (not 1N....).  There is also \"IN-COM\".  They are axial top-hat
package.
Click to expand...

At a guess, they sound like a voltage reference part.

--
Adrian C
 
On Thu, 7 Apr 2022 11:13:09 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

Just curious - it\'s puzzling, but I have no need for information.

I found these diodes (new) at the dump & I can\'t find anything about
them. I\'ve gone so far as to scroll through 100\'s of Google images.

Anyhow, they\'re marked with a plain diode symbol, but the ID is weird:
\"IC1790\" (not 1N....). There is also \"IN-COM\". They are axial top-hat
package.

The more I looked without finding anything, the more curious that I
became. Any help would be a relief.

Thanks, Bob
Click to expand...

I\'d probe it at low current for zenering behavior.

Skinny top-hat DO6 (vs DO1, DO2, DO3, DO210AA) axial parts weren\'t
suitable for HV service.

DO13 lost the top-hat while maintaining hermeticity.

That could also (almost) be a cyrillic marking, given the limited
characters used.

RL
 
On Thu, 7 Apr 2022 11:13:09 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

I found these diodes (new) at the dump & I can\'t find anything about
them. I\'ve gone so far as to scroll through 100\'s of Google images.
Click to expand...

The way the supply chain shortages are going, dumpster diving might
soon become a major source for components.

Anyhow, they\'re marked with a plain diode symbol, but the ID is weird:
\"IC1790\" (not 1N....). There is also \"IN-COM\". They are axial top-hat
package.
Click to expand...

That\'s an old, late 1950\'s to early 1960\'s style package. They were
called \"top hat\" diodes. Something like these:
<https://www.google.com/search?q=vintage+top+hat+diodes&tbm=isch>

I didn\'t have any luck finding who in-co might be. I found this:
<https://www.linkedin.com/company/in-co./>
but that\'s obviously not a diode manufacturer.

Judging by the lead diameter in the photo, methink the IC1790 is some
kind of power diode, zener, or whatever.

Got a curve tracer? I can tell quite a bit about the diode from a
curve tracer display:
<https://www.tek.com/en/blog/i-v-curve-tracer>
<https://www.ebay.com/sch/i.html?_nkw=curve+tracer>
<https://www.amazon.com/s?k=curve+tracer>
or just build your own curve tracer:
<https://www.google.com/search?q=build+a+curve+tracer>

Good luck.
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
 
On 07/04/2022 17:28, Bob Engelhardt wrote:
On 4/7/2022 12:26 PM, Bob Engelhardt wrote:
On 4/7/2022 11:24 AM, Sjouke Burry wrote:

One picture is worth a thousand words.

Maybe ... https://imgur.com/PShcDYZ

The \"brim\" is the cathode.
Click to expand...

Long shot ...

This is something in a similar type of package
https://www.jotrin.com/product/parts/JAN1N6067A

It\'s called a transient voltage suppressor (TVS) - a kind of Zener.

Does that the diode logo have a straight thin line across it, or is the
line bent with angular tips?

There are also some diode manufacturers that use the diode symbol in
their logo.

A picture of that symbol would be great as well.

--
Adrian C
 
bobenge...@gmail.com wrote:
========================
Just curious - it\'s puzzling, but I have no need for information.

I found these diodes (new) at the dump & I can\'t find anything about
them. I\'ve gone so far as to scroll through 100\'s of Google images.

Anyhow, they\'re marked with a plain diode symbol, but the ID is weird:
\"IC1790\" (not 1N....). There is also \"IN-COM\". They are axial top-hat
package.

The more I looked without finding anything, the more curious that I
became. Any help would be a relief.
Click to expand...

** I guess you have verified it is a Si diode with your DMM?
With bench PSUs it is easy to get other specs.

Maybe connect one across a standard ( not alkaline) AA cell a see what happens.

....... Phil
 
On 4/7/2022 4:46 PM, Adrian Caspersz wrote:
Does that the diode logo have a straight thin line across it, or is the
line bent with angular tips?
....

A picture of that symbol would be great as well.
Click to expand...

No, the symbol is just plain diode (triangle & strait bar)


On 4/7/2022 4:15 PM, Jeff Liebermann wrote:
....
I didn\'t have any luck finding who in-co might be. I found this:
...
Click to expand...

It\'s actually IN-COM - the \"M\" wraps around. But IN-COM can\'t be found
either.

You say it could be late 50\'s - I think in the 50\'s there were a lot of
transistor start-ups looking to get on the band wagon. If so, IN-COM
could have been one of them that just faded away.

When I found them, there must have been a couple thousand of them. A
wild ass guess would be that a town resident was involved with IN-COM &
took some home. That resident now down-sizing. Or similarly, a
resident involved with a company that used this diode in a product.

Some crude bench supply tests: handles 3A forward (1V drop), getting
warm. The heat from 5A (8W) discolors it, but it doesn\'t open (10
minutes). It breaks down with reverse voltage of 80V (peak, 60v RMS
full wave).
 
bobenge...@gmail.com wrote:
========================
Some crude bench supply tests: handles 3A forward (1V drop), getting
warm. The heat from 5A (8W) discolors it, but it doesn\'t open (10
minutes). It breaks down with reverse voltage of 80V
Click to expand...

** Hmmm....

You have a pretty ordinary 3A Si diode.

The modern 1N5401 has much lower forward voltage drops.


......Phil
 
On Thu, 7 Apr 2022 21:16:56 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

On 4/7/2022 4:46 PM, Adrian Caspersz wrote:
Does that the diode logo have a straight thin line across it, or is the
line bent with angular tips?
...

A picture of that symbol would be great as well.


No, the symbol is just plain diode (triangle & strait bar)


On 4/7/2022 4:15 PM, Jeff Liebermann wrote:
...
I didn\'t have any luck finding who in-co might be. I found this:
...

It\'s actually IN-COM - the \"M\" wraps around. But IN-COM can\'t be found
either.

You say it could be late 50\'s - I think in the 50\'s there were a lot of
transistor start-ups looking to get on the band wagon. If so, IN-COM
could have been one of them that just faded away.

When I found them, there must have been a couple thousand of them. A
wild ass guess would be that a town resident was involved with IN-COM &
took some home. That resident now down-sizing. Or similarly, a
resident involved with a company that used this diode in a product.

Some crude bench supply tests: handles 3A forward (1V drop), getting
warm. The heat from 5A (8W) discolors it, but it doesn\'t open (10
minutes). It breaks down with reverse voltage of 80V (peak, 60v RMS
full wave).
Click to expand...

1N1790 is a 62V 10% 1W zener.

RL
 
legg wrote:
===========

1N1790 is a 62V 10% 1W zener.
Click to expand...

** Looks a hell of a lot like it.
Made by Motorola and IR likely in the 60s or early 70s.


..... Phil
 
On Thu, 7 Apr 2022 21:16:56 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

On 4/7/2022 4:46 PM, Adrian Caspersz wrote:
Does that the diode logo have a straight thin line across it, or is the
line bent with angular tips?
...

A picture of that symbol would be great as well.


No, the symbol is just plain diode (triangle & strait bar)


On 4/7/2022 4:15 PM, Jeff Liebermann wrote:
...
I didn\'t have any luck finding who in-co might be. I found this:
...

It\'s actually IN-COM - the \"M\" wraps around. But IN-COM can\'t be found
either.

You say it could be late 50\'s - I think in the 50\'s there were a lot of
transistor start-ups looking to get on the band wagon. If so, IN-COM
could have been one of them that just faded away.

When I found them, there must have been a couple thousand of them. A
wild ass guess would be that a town resident was involved with IN-COM &
took some home. That resident now down-sizing. Or similarly, a
resident involved with a company that used this diode in a product.

Some crude bench supply tests: handles 3A forward (1V drop), getting
warm. The heat from 5A (8W) discolors it, but it doesn\'t open (10
minutes). It breaks down with reverse voltage of 80V (peak, 60v RMS
full wave).
Click to expand...

1S1790 is a 150V zener in that case size.

S is C in cyrillic.

RL
 
On Thu, 7 Apr 2022 21:16:56 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

On 4/7/2022 4:46 PM, Adrian Caspersz wrote:
Does that the diode logo have a straight thin line across it, or is the
line bent with angular tips?
...

A picture of that symbol would be great as well.


No, the symbol is just plain diode (triangle & strait bar)
Click to expand...

Perhaps an abbreviated International Rectifier logo?
<https://www.google.com/search?q=international+rectifier+logos&tbm=isch>

On 4/7/2022 4:15 PM, Jeff Liebermann wrote:
...
I didn\'t have any luck finding who in-co might be. I found this:
...

It\'s actually IN-COM - the \"M\" wraps around. But IN-COM can\'t be found
either.
Click to expand...

Oops. I took the name from your photo.

You say it could be late 50\'s - I think in the 50\'s there were a lot of
transistor start-ups looking to get on the band wagon. If so, IN-COM
could have been one of them that just faded away.
Click to expand...

That\'s possible. However, the late 1950\'s guess is based on the
prevalence of similar looking \"top hat\" packages. I vaguely recall
that this package slowly disappeared in the mid 1960\'s.

When I found them, there must have been a couple thousand of them. A
wild ass guess would be that a town resident was involved with IN-COM &
took some home. That resident now down-sizing. Or similarly, a
resident involved with a company that used this diode in a product.
Click to expand...

That\'s exactly what happened to me when I was a senior in high school
in 1965. I got a tour of PSI (Pacific Semiconductors). They were in
the process of being acquired by TRW:
<https://www.chipsetc.com/psi-pacific-semiconductors.html>
and were disposing of most everything with PSI printed on it. I went
home with a large cardboard box full of floor sweepings. I probably
could have gotten more if I transportation. Most ended up being
redistributed to the schools electronics students. I went home with
two shoe boxes stuffed with mostly diodes, some of which I still have
today.

Some crude bench supply tests: handles 3A forward (1V drop), getting
warm. The heat from 5A (8W) discolors it, but it doesn\'t open (10
minutes). It breaks down with reverse voltage of 80V (peak, 60v RMS
full wave).
Click to expand...

If the reverse breakdown voltage happens abruptly, that\'s zener
action. 79V zener perhaps? However, if the reverse breakdown corner
is gradual and rounded, it\'s an ordinary power diode. Throw together
an I-V curve tracer and see what it looks like on an oscilloscope:
<https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/articles-iv2.gif>
<https://circuitcellar.com/research-design-hub/create-your-own-i-v-curve-tracer/>


--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
 
On Thu, 07 Apr 2022 23:50:50 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Thu, 7 Apr 2022 21:16:56 -0400, Bob Engelhardt
BobEngelhardt@comcast.net> wrote:
No, the symbol is just plain diode (triangle & strait bar)

Perhaps an abbreviated International Rectifier logo?
https://www.google.com/search?q=international+rectifier+logos&tbm=isch
Click to expand...

Here\'s another possible diode logo:
<https://www.rectron.com>

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
 
On 4/7/2022 9:16 PM, Bob Engelhardt wrote:
....
Some crude bench supply tests: handles 3A forward (1V drop), getting
warm.  The heat from 5A (8W) discolors it, but it doesn\'t open (10
minutes).  It breaks down with reverse voltage of 80V (peak, 60v RMS
full wave).
Click to expand...

I was thinking these were plain diodes, since that is the symbol on
them, so my test did not control the reverse current and let it vaporize.

I did another, with \"pure\" DC (instead of full wave) & limited the
current. Also measured the current as it approached breakdown. It
started at 46V (1ma), growing to 100ma at 62v, just before it broke down
at 64v.

Then it went crazy: the voltage across it dropped to 7V (650ma) & 6V at
800ma. Is that the way a plain diode breaks down?

Since I limited the current, it did not vaporize and the test could be
repeated.
 
On 4/8/2022 5:11 PM, Bob Engelhardt wrote:
....
Then it went crazy:  the voltage across it dropped to 7V (650ma) & 6V at
800ma.
...
Click to expand...

Oh, wait ... once it broke down, the current through the limiting
resistor (100R) dropped most of the voltage there.
 
On 4/8/2022 2:50 AM, Jeff Liebermann wrote:
....

Throw together
an I-V curve tracer and see what it looks like on an oscilloscope:
https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/articles-iv2.gif
https://circuitcellar.com/research-design-hub/create-your-own-i-v-curve-tracer/
Click to expand...

I had Googled DIY curve tracer & got really elaborate circuits, so I
didn\'t pursue it. Is the one you linked to really all you need? (AC & 2
resistors)?

Doesn\'t that have the same problem that I had: once the diode breaks
down & conducts, voltage is dropped across the resistors and the voltage
across the diode drops, a lot?
 
bobenge...@gmail.com wrote:

==========================
I did another, with \"pure\" DC (instead of full wave) & limited the
current. Also measured the current as it approached breakdown. It
started at 46V (1ma), growing to 100ma at 62v, just before it broke down
at 64v.

** A 1W zener will not like 6.4 watts.
Click to expand...

Then it went crazy: the voltage across it dropped to 7V (650ma) & 6V at
800ma. Is that the way a plain diode breaks down?
Click to expand...

** That is failure, not breakdown.
The Si chip has melted.


....... Phil
 
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