Chinese Germanium 1N34

On 2/9/2015 8:31 PM, David Eather wrote:
On Mon, 09 Feb 2015 11:03:05 +1000, Phil Allison <pallison49@gmail.com
wrote:

Baron wrote:


** Err - try visual inspection first:

http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg



They look nothing like that. But if 1N34 is a pretty generic diode,
there could be more than one manufacturer I assume.

The drop is about .2-.3V but the first datasheet I looked up,
doesn't match the parameters I'm getting.

No it doesn't look like any of my 1N34's either !


** Wot - not clear glass and no die on the end of a header or tiny
wire making a point contact?

Sure your 1N34s are genuine ?



.... Phil




Do these ones look OK? I can't tell, my eyes keep going watery. (Anyone
on heart meds should not open the link!)

http://www.ebay.com/itm/X-1-pcs-1N34A-Germanium-Diode-1st-class-post-uk- guitar-effects-pedal-use-/261498065100?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3ce27fd0cc
Click to expand...
Ya better hurry, only two left and he (says) he sold 78.
He goes on to say you can get a shipping quote if you want to buy
massive quantities. Quantity 1 - $152.58 USD, That's greedy, he should
offer free shipping. :)
Mikek

---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com
 
On 2/11/2015 10:47 AM, George Herold wrote:
On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote:
On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed"
mhdpublic@gmail.com> wrote:

On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote:
M. Hamed wrote:

So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes

** Err - try visual inspection first:

http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg



... Phil

They look nothing like that. But if 1N34 is a pretty generic diode, there could be more than one manufacturer I assume.

The drop is about .2-.3V but the first datasheet I looked up, doesn't match the parameters I'm getting.

1N34s could be all over the place. Point contacts are sorta random.

They have a high series resistance, so the low voltage drop of
germanium only happens at very low currents.

Germanium is silly, when silicon schottky diodes are available.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

OK for fun I did the I-V of a 1N34.

https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0

I thought Germanium were supposed to be "more ideal" than Si diodes.
But the point contact thing looks nothing like the ideal diode model.
(log/ linear plot)

George H.
Click to expand...
Looks like you have some gross amount of series resistance and parallel
conductance. Not too surprising in a 1N34A!

Cheers

Phil

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
On Wed, 11 Feb 2015, George Herold wrote:

On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote:
On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed"
mhdpublic@gmail.com> wrote:

On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote:
M. Hamed wrote:

So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes

** Err - try visual inspection first:

http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg



... Phil

They look nothing like that. But if 1N34 is a pretty generic diode, there could be more than one manufacturer I assume.

The drop is about .2-.3V but the first datasheet I looked up, doesn't match the parameters I'm getting.

1N34s could be all over the place. Point contacts are sorta random.

They have a high series resistance, so the low voltage drop of
germanium only happens at very low currents.

Germanium is silly, when silicon schottky diodes are available.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

OK for fun I did the I-V of a 1N34.

https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0

I thought Germanium were supposed to be "more ideal" than Si diodes.
But the point contact thing looks nothing like the ideal diode model.
(log/ linear plot)

Nobody said they were ideal.
Click to expand...

They are "the best" in some circumstances, which probably at this point
means when low forward voltage drop is desired.

Michael
 
On Wed, 11 Feb 2015 09:50:29 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Wednesday, February 11, 2015 at 11:56:16 AM UTC-5, John Larkin wrote:
On Wed, 11 Feb 2015 07:47:54 -0800 (PST), George Herold
gherold@teachspin.com> wrote:

On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote:
On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed"
mhdpublic@gmail.com> wrote:

On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote:
M. Hamed wrote:

So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes

** Err - try visual inspection first:

http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg



... Phil

They look nothing like that. But if 1N34 is a pretty generic diode, there could be more than one manufacturer I assume.

The drop is about .2-.3V but the first datasheet I looked up, doesn't match the parameters I'm getting.

1N34s could be all over the place. Point contacts are sorta random.

They have a high series resistance, so the low voltage drop of
germanium only happens at very low currents.

Germanium is silly, when silicon schottky diodes are available.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

OK for fun I did the I-V of a 1N34.

https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0

I thought Germanium were supposed to be "more ideal" than Si diodes.
But the point contact thing looks nothing like the ideal diode model.
(log/ linear plot)

George H.

Yeah, the Ge is going ohmic past roughly 1 mA. But another 1N34 might
be very different.

Try a small-signal schottky, 1N5711 maybe. That's a high-barrier part.
The low-barrier parts, rated a few volts reverse, are even better.

OK 1N5711 added to plot... I think you can use the same dropbox link.
Click to expand...

The best RF detector diodes are germanium back diodes, which are
actually tunnel diodes with very low peak point currents. They are
used "backwards" from the obvious polarity.




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Mon, 9 Feb 2015 17:28:43 -0800 (PST), Phil Allison
<pallison49@gmail.com> wrote:

Baron wrote:


Oops, Sorry Phil, Guys. A brain fart !

I've just looked at the ones I have, they are 1N23. Still in the
lead foil packets.


** So they look like little bullets:

http://www.ciel-electronique.com/catalogue/Larges/JAN1N23WE.jpg



Yes those are the ones I've got.


** Dems are *silicon* point contact diodes.
Click to expand...

During WWII, we (US and Brits) were using silicon, germanium, and
gallium arsenide point-contact diodes as mixers up to 30 GHz. One of
the RadLab books notes that "a semiconductor triode should be
possible."




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Wednesday, February 11, 2015 at 2:16:18 PM UTC-5, Phil Hobbs wrote:
On 2/11/2015 10:47 AM, George Herold wrote:
On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote:
On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed"
mhdpublic@gmail.com> wrote:

On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote:
M. Hamed wrote:

So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes

** Err - try visual inspection first:

http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg



... Phil

They look nothing like that. But if 1N34 is a pretty generic diode, there could be more than one manufacturer I assume.

The drop is about .2-.3V but the first datasheet I looked up, doesn't match the parameters I'm getting.

1N34s could be all over the place. Point contacts are sorta random.

They have a high series resistance, so the low voltage drop of
germanium only happens at very low currents.

Germanium is silly, when silicon schottky diodes are available.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

OK for fun I did the I-V of a 1N34.

https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0

I thought Germanium were supposed to be "more ideal" than Si diodes.
But the point contact thing looks nothing like the ideal diode model.
(log/ linear plot)

George H.

Looks like you have some gross amount of series resistance and parallel
conductance. Not too surprising in a 1N34A!
Click to expand...

The point contact is just weird. Here's a plot of the same data
but log-log.

https://www.dropbox.com/s/5irzzrpshuqgqfk/1N34-B.BMP?dl=0

My eye wanted to put put two lines through the data,
so lines were added by eye. Two power laws?

George H.
Cheers

Phil

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
Click to expand...
 
So first, here is what mine look like:

http://cfnewsads.thomasnet.com/images/cmsimage/image/automation-electronics/zener-diode-sample.JPG

except that they don't seem to have any visible marking
 
Second, I wanted to create a diode curve tracer to test these new diodes using scope X-Y mode. Problem of course that my ramp generator is grounded so I can't probe at two different point pairs.

It's funny how I had all these complicated ideas to solve this problem including using a difference amplifier to convert the voltage difference across the diode to a voltage referenced to ground.

Then I decided to google search, and after 5 mins, it's funny how the solution was way simpler. Plug the function generator into a 3-2 prong adapter. DUH!
 
On Thursday, February 12, 2015 at 12:11:21 PM UTC-8, George Herold wrote:

OK for fun I did the I-V of a 1N34.

https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0

I thought Germanium were supposed to be "more ideal" than Si diodes.
But the point contact thing looks nothing like the ideal diode model.
(log/ linear plot)

The point contact is just weird. Here's a plot of the same data
but log-log.

https://www.dropbox.com/s/5irzzrpshuqgqfk/1N34-B.BMP?dl=0
Click to expand...

That's normal. The so-called 'ideal diode equation' is Shockley's model
for a planar diode (i.e. the depletion region is constant area, variable thickness),
but a point=contact diode has a depletion region which is a hemisphere around
the point of contact (area proportional to R squared).

The Ge point contact diodes worked well, because the low bandgap
made impurities relatively benign (and that contact point has to be
at the semiconductor surface, which is always dirty). Capacitance was
low, and gigahertz operation was easy. Silicon point contact isn't as
reliable because there's more dirt sensitivity, and the higher forward
voltage means a surface electric field (attracts more dirt).

Shottky diodes for RF are not point-contact types.
Are ANY point-contact diodes still in production?
 
Finally, with my scope diode curve tracer, I got some data.

1- A schottky diode (1N5189) -> turns on around .2V and then current goes up really fast
2- A Germanium diode with clear glass and a green stripe -> turns on around .2V but current rises REALLY slowly with voltage. I knew this already. Germanium diodes have less steep curve and that's why they have some application in audio.

3- My presumed 1N34 -> turns on around .2V but current rise slower than (1) and faster than (2).

So at this point I wasn't sure, so I dug around for more "clear glass" germaniums I had. I found one that looks almost identical to diode #2 but with a black stripe rather than a green one. I put it in my test circuit, and the result is almost identical to #3.

So I can't tell if my diode is 1N34 or not, but I'm positive it could be a Germanium diode since it acts like another Germanium diode.

Time to give the seller positive feedback!
 
M. Hamed wrote:

So first, here is what mine look like:

http://cfnewsads.thomasnet.com/images/cmsimage/image/automation-electronics/zener-diode-sample.JPG
Click to expand...

** Well, they are cleary zener diodes - like the link says.

The chip is trapped between two headers to carry heat away.

Small silicon diodes like the 1N4148 look similar.

It sure ain't no point contact type.



..... Phil
 
On Friday, February 13, 2015 at 12:07:17 AM UTC-5, whit3rd wrote:
On Thursday, February 12, 2015 at 12:11:21 PM UTC-8, George Herold wrote:

OK for fun I did the I-V of a 1N34.

https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0

I thought Germanium were supposed to be "more ideal" than Si diodes.
But the point contact thing looks nothing like the ideal diode model.
(log/ linear plot)

The point contact is just weird. Here's a plot of the same data
but log-log.

https://www.dropbox.com/s/5irzzrpshuqgqfk/1N34-B.BMP?dl=0

That's normal. The so-called 'ideal diode equation' is Shockley's model
for a planar diode (i.e. the depletion region is constant area, variable thickness),
but a point=contact diode has a depletion region which is a hemisphere around
the point of contact (area proportional to R squared).
Click to expand...

Ahh OK so as I forward bias it the area of the depletion region changes.
(Does it get smaller with forward bias..? Just thinking out loud, I'd guess
it gets larger in area with a reverse bias.)

Looking at my rather sketchy data, the slope at low bias is ~1
(in a power law) and ~2.5 or so at higher bias voltages...
with the crossover point near 30 mV or so... Near the thermal voltage.
(I have no idea if that is significant or not.)

I could only find I-V of reversed biased Ge on a quick web search.

https://circle.ubc.ca/bitstream/handle/2429/40864/UBC_1957_A6_7%20B8%20S8.pdf?sequence=1

(I like research done before I was born. :^)

George H.
The Ge point contact diodes worked well, because the low bandgap
made impurities relatively benign (and that contact point has to be
at the semiconductor surface, which is always dirty). Capacitance was
low, and gigahertz operation was easy. Silicon point contact isn't as
reliable because there's more dirt sensitivity, and the higher forward
voltage means a surface electric field (attracts more dirt).

Shottky diodes for RF are not point-contact types.
Are ANY point-contact diodes still in production?
Click to expand...
 
On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote:
** Well, they are cleary zener diodes - like the link says.
Click to expand...

Have you ever seen low forward voltage zener diodes? That would be new to me. The forward drop on these are about .2V-.3V
 
M. Hamed wrote:

Phil Allison wrote:
** Well, they are cleary zener diodes - like the link says.


Have you ever seen low forward voltage zener diodes? That would be new to me. The forward drop on these are about .2V-.3V
Click to expand...

** But the pic IS of some Philips zeners - it damn we says so.

http://cfnewsads.thomasnet.com/images/cmsimage/image/automation-electronics/zener-diode-sample.JPG

Piss off fool.



..... Phil
 
On Fri, 13 Feb 2015, M. Hamed wrote:

On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote:

** Well, they are cleary zener diodes - like the link says.


Have you ever seen low forward voltage zener diodes? That would be new to me. The forward drop on these are about .2V-.3V

A zener by definition is reverse biased.
Click to expand...

Using diodes as voltage regulators is not uncommon. Just put a bunch in
series to get the desired voltage from the individual voltage drops, and
then feed that with a resistor. But it's not a "zener effect".

Germanium diodes can be used the same way, but their forward voltage drop
is lower, so unless the desired voltage is low, you'd need more. And the
termperature response is different from silicon, and that may be a factor.

It's not uncommon to use a forward biased silicon diode as the sensor in a
digital thermometer, the characterstic is well known. I can't remember if
germanium diodes were used that way, but if so, the response would be
different.

But this factors in when forward biasing diodes for better low level
response, such as detecting low RF voltages. Once you bias the diode, the
will react to temperature, so you need another diode similarly biased but
with no RF applied to it, to balance out the temperature response.

Michael
 
Michael Black wrote:

A zener by definition is reverse biased.
Click to expand...

** But in practice may be either.

Back to back zeners are very commonly used for anti-static protection plus for AC voltage limiting and clamping in all kinds of analogue circuitry.



.... Phil
 
On Friday, February 13, 2015 at 6:16:58 PM UTC-7, Phil Allison wrote:
** But the pic IS of some Philips zeners - it damn we says so.
Click to expand...

That's why I said "Looks like" not "exactly absolutely identical"

Piss off fool.
Click to expand...

Have you been bullied as a child? You know there is therapy for that, right?
 
In article <096d6805-58d6-4320-9de6-039a850a4377@googlegroups.com>,
mhdpublic@gmail.com says...
On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote:

** Well, they are cleary zener diodes - like the link says.


Have you ever seen low forward voltage zener diodes? That would be new to me. The forward drop on these are about .2V-.3V
Click to expand...

sure I have, after they get hammered a few times! :)

Jamie
 
On 2/13/2015 8:49 PM, Michael Black wrote:
On Fri, 13 Feb 2015, M. Hamed wrote:

On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote:

** Well, they are cleary zener diodes - like the link says.


Have you ever seen low forward voltage zener diodes? That would be new
to me. The forward drop on these are about .2V-.3V

A zener by definition is reverse biased.
Click to expand...

What happens if you forward bias one? Thought ceases to exist? Or does
it just disappear in a flash of logic?

I'll have to try it. ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
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