Chinese Germanium 1N34

[Pimpom]

George Herold wrote:

On Wednesday, February 18, 2015 at 1:25:53 AM UTC-5, Pimpom
wrote:
whit3rd wrote:

A word of warning: don't test the reverse bias on
point-contact,
or light emitting, or low-noise photodiodes. Those devices
have
very sensitive near-surface regions that only stay clean if
the
electric field isn't given an unexpected polarity.

I've seen LEDs in cheap Chinese and Indian products run
directly
from 230VAC with a single series resistor and nothing else.
That
obviously places the LED in reverse breakdown every half
cycle. I
haven't paid enough attention to see if/how their performance
changes with time.

I reversed biased several LEDs.. most were good up to ~100V or
so..
230VAC seems like a lot... but maybe with the "right" led.

I see now how my post could be incorrectly interpreted. I mean a
*single* LED used as a power indicator, not a string of them, and
without any other component shunting it to prevent reverse
operation. The series resistor limits the current in both forward
and reverse breakdown mode. Usually these are run at a mA or two.
The preceding post by whit3rd made me wonder if LEDs used like
this suffer significant degradation in light ouput or lifespan.

 

[John Larkin]

On Wed, 18 Feb 2015 06:17:28 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Tuesday, February 17, 2015 at 10:51:44 PM UTC-5, John Larkin wrote:
On Tue, 17 Feb 2015 12:47:47 -0800 (PST), whit3rd <whit3rd@gmail.com
wrote:

On Sunday, February 15, 2015 at 10:35:49 AM UTC-8, Michael Black wrote:
On Sun, 15 Feb 2015, David Eather wrote:

...by the way all diodes are zener diodes - we just don't normally
run them in the breakdown region.

Yes, all diodes can "zener" but they are reversed biased.

A word of warning: don't test the reverse bias on point-contact,
or light emitting, or low-noise photodiodes.

Reverse biasing photodiodes is the usual way to use them. It reduces
their capacitance and makes them a lot faster.

Anyone tried taking a garden variety photodiode up to the point
where it starts avalanching?
(Maybe in a dark room... there are some thing better done with the
lights off :^)

No, but that's what an APD does (probably with special doping)


--

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

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

 

[George Herold]

On Wednesday, February 18, 2015 at 2:10:24 PM UTC-5, George Herold wrote:

On Wednesday, February 18, 2015 at 11:46:32 AM UTC-5, John Larkin wrote:
On Wed, 18 Feb 2015 06:17:28 -0800 (PST), George Herold
gherold@teachspin.com> wrote:

On Tuesday, February 17, 2015 at 10:51:44 PM UTC-5, John Larkin wrote:
On Tue, 17 Feb 2015 12:47:47 -0800 (PST), whit3rd <whit3rd@gmail.com
wrote:

On Sunday, February 15, 2015 at 10:35:49 AM UTC-8, Michael Black wrote:
On Sun, 15 Feb 2015, David Eather wrote:

...by the way all diodes are zener diodes - we just don't normally
run them in the breakdown region.

Yes, all diodes can "zener" but they are reversed biased.

A word of warning: don't test the reverse bias on point-contact,
or light emitting, or low-noise photodiodes.

Reverse biasing photodiodes is the usual way to use them. It reduces
their capacitance and makes them a lot faster.

Anyone tried taking a garden variety photodiode up to the point
where it starts avalanching?
(Maybe in a dark room... there are some thing better done with the
lights off :^)


No, but that's what an APD does (probably with special doping)

Hmm my post disappeared.
OK I reverse biased an osi opto-electronics PIN-3CD (With 100 k ohm to limit the current.) It didn't avalanche till ~150V. But the avalanche current was independent of the photo current... Like it was avalanching at the edges or something. I've had "edge issues" with this PD in the past.... I need some other small PD's.

Update.. I did find some other PD's
They all seemed to avalanche around 100-150V.
With the avalanche "channel" not coupled with the photo "channel".

Which I guess is why you have to pay more for APD's...

George H.

George H.



--

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

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

 

[Charlie+]

On Wed, 18 Feb 2015 20:26:02 +0530, "Pimpom" <Pimpom@invalid.invalid>
wrote as underneath :

George Herold wrote:
On Wednesday, February 18, 2015 at 1:25:53 AM UTC-5, Pimpom
wrote:
whit3rd wrote:

A word of warning: don't test the reverse bias on
point-contact,
or light emitting, or low-noise photodiodes. Those devices
have
very sensitive near-surface regions that only stay clean if
the
electric field isn't given an unexpected polarity.

I've seen LEDs in cheap Chinese and Indian products run
directly
from 230VAC with a single series resistor and nothing else.
That
obviously places the LED in reverse breakdown every half
cycle. I
haven't paid enough attention to see if/how their performance
changes with time.

I reversed biased several LEDs.. most were good up to ~100V or
so..
230VAC seems like a lot... but maybe with the "right" led.

I see now how my post could be incorrectly interpreted. I mean a
*single* LED used as a power indicator, not a string of them, and
without any other component shunting it to prevent reverse
operation. The series resistor limits the current in both forward
and reverse breakdown mode. Usually these are run at a mA or two.
The preceding post by whit3rd made me wonder if LEDs used like
this suffer significant degradation in light ouput or lifespan.

I have used since 2002 a couple of 3mm hibright red LEDs like this as
indicators but running them at less than 0.00005A (240v mains R series
at 470K) nothing like your figures 1-2mA. So this works fine just for
indicators but I would be wary of doing this at anything like full LED
brightness. Output looks same as when installed.

 

[Jasen Betts]

On 2015-02-18, George Herold <gherold@teachspin.com> wrote:

I've seen LEDs in cheap Chinese and Indian products run directly
from 230VAC with a single series resistor and nothing else. That
obviously places the LED in reverse breakdown every half cycle. I
haven't paid enough attention to see if/how their performance
changes with time.

I reversed biased several LEDs.. most were good up to ~100V or so..
230VAC seems like a lot... but maybe with the "right" led.

I killed one with only 9V


--
umop apisdn

 

[Pimpom]

Jasen Betts wrote:

On 2015-02-18, George Herold <gherold@teachspin.com> wrote:

I've seen LEDs in cheap Chinese and Indian products run
directly
from 230VAC with a single series resistor and nothing else.
That
obviously places the LED in reverse breakdown every half
cycle. I
haven't paid enough attention to see if/how their performance
changes with time.

I reversed biased several LEDs.. most were good up to ~100V or
so..
230VAC seems like a lot... but maybe with the "right" led.

I killed one with only 9V

Must have been without a series resistor or other current
limiter.

 

[George Herold]

On Thursday, February 19, 2015 at 7:08:23 PM UTC-5, Maynard A. Philbrook Jr. wrote:

In article <e7586579-3c71-4500-a14d-7f52852f941b@googlegroups.com>,
gherold@teachspin.com says...

Yes, all diodes can "zener" but they are reversed biased.

A word of warning: don't test the reverse bias on point-contact,
or light emitting, or low-noise photodiodes.

Reverse biasing photodiodes is the usual way to use them. It reduces
their capacitance and makes them a lot faster.

Anyone tried taking a garden variety photodiode up to the point
where it starts avalanching?
(Maybe in a dark room... there are some thing better done with the
lights off :^)

George H.



did that with a clear LED using a 1M R as a ballast .

It gave some interesting results at around 25V


Jamie

Me too! (it all started on SEB after all.)
http://teachspin.com/newsletters/TeachSpin_MAY13FINALFOR%20WEB.pdf

The leds are from purdy electronics AND113R and AND114R
http://www.purdyelectronics.com/products/red_leds

For best results as a detector get the 113R "clear"
sand down most of the plastic till you get near the wire bond
and then polish out the scratches.

George H.

 

[Maynard A. Philbrook Jr.]

In article <e7586579-3c71-4500-a14d-7f52852f941b@googlegroups.com>,
gherold@teachspin.com says...

Yes, all diodes can "zener" but they are reversed biased.

A word of warning: don't test the reverse bias on point-contact,
or light emitting, or low-noise photodiodes.

Reverse biasing photodiodes is the usual way to use them. It reduces
their capacitance and makes them a lot faster.

Anyone tried taking a garden variety photodiode up to the point
where it starts avalanching?
(Maybe in a dark room... there are some thing better done with the
lights off :^)

George H.

did that with a clear LED using a 1M R as a ballast .

It gave some interesting results at around 25V


Jamie

 

[Maynard A. Philbrook Jr.]

In article <57752ec8-c635-4488-9a4b-4a37116e33fc@googlegroups.com>,
gherold@teachspin.com says...

On Thursday, February 19, 2015 at 7:08:23 PM UTC-5, Maynard A. Philbrook Jr. wrote:
In article <e7586579-3c71-4500-a14d-7f52852f941b@googlegroups.com>,
gherold@teachspin.com says...

Yes, all diodes can "zener" but they are reversed biased.

A word of warning: don't test the reverse bias on point-contact,
or light emitting, or low-noise photodiodes.

Reverse biasing photodiodes is the usual way to use them. It reduces
their capacitance and makes them a lot faster.

Anyone tried taking a garden variety photodiode up to the point
where it starts avalanching?
(Maybe in a dark room... there are some thing better done with the
lights off :^)

George H.



did that with a clear LED using a 1M R as a ballast .

It gave some interesting results at around 25V


Jamie

Me too! (it all started on SEB after all.)
http://teachspin.com/newsletters/TeachSpin_MAY13FINALFOR%20WEB.pdf

The leds are from purdy electronics AND113R and AND114R
http://www.purdyelectronics.com/products/red_leds

For best results as a detector get the 113R "clear"
sand down most of the plastic till you get near the wire bond
and then polish out the scratches.

George H.

do you also use a file on carbon composite resistors to get
the value you need when in a pinch, too?

Jamie

 

[Charlie+]

On Thu, 19 Feb 2015 08:02:35 +0000, Charlie+ <charlie@xxx.net> wrote as
underneath :

snip

I have used since 2002 a couple of 3mm hibright red LEDs like this as
indicators but running them at less than 0.00005A (240v mains R series
at 470K) nothing like your figures 1-2mA. So this works fine just for
indicators but I would be wary of doing this at anything like full LED
brightness. Output looks same as when installed.

Sorry correction on checking circuit - used these LEDs like this since
1995 when I updated my C/H system... strewth - nearly 20 years ago!

 

[Jasen Betts]

On 2015-02-19, Pimpom <Pimpom@invalid.invalid> wrote:

Jasen Betts wrote:
On 2015-02-18, George Herold <gherold@teachspin.com> wrote:

I've seen LEDs in cheap Chinese and Indian products run
directly
from 230VAC with a single series resistor and nothing else.
That
obviously places the LED in reverse breakdown every half
cycle. I
haven't paid enough attention to see if/how their performance
changes with time.

I reversed biased several LEDs.. most were good up to ~100V or
so..
230VAC seems like a lot... but maybe with the "right" led.

I killed one with only 9V

Must have been without a series resistor or other current
limiter.

560R



--
umop apisdn

 

[George Herold]

On Thursday, February 19, 2015 at 9:59:54 PM UTC-5, Maynard A. Philbrook Jr. wrote:

In article <57752ec8-c635-4488-9a4b-4a37116e33fc@googlegroups.com>,
gherold@teachspin.com says...

On Thursday, February 19, 2015 at 7:08:23 PM UTC-5, Maynard A. Philbrook Jr. wrote:
In article <e7586579-3c71-4500-a14d-7f52852f941b@googlegroups.com>,
gherold@teachspin.com says...

Yes, all diodes can "zener" but they are reversed biased.

A word of warning: don't test the reverse bias on point-contact,
or light emitting, or low-noise photodiodes.

Reverse biasing photodiodes is the usual way to use them. It reduces
their capacitance and makes them a lot faster.

Anyone tried taking a garden variety photodiode up to the point
where it starts avalanching?
(Maybe in a dark room... there are some thing better done with the
lights off :^)

George H.



did that with a clear LED using a 1M R as a ballast .

It gave some interesting results at around 25V


Jamie

Me too! (it all started on SEB after all.)
http://teachspin.com/newsletters/TeachSpin_MAY13FINALFOR%20WEB.pdf

The leds are from purdy electronics AND113R and AND114R
http://www.purdyelectronics.com/products/red_leds

For best results as a detector get the 113R "clear"
sand down most of the plastic till you get near the wire bond
and then polish out the scratches.

George H.

do you also use a file on carbon composite resistors to get
the value you need when in a pinch, too?

Jamie

I've heard about filling carbon composites, but I've never done it.
(almost all 1% metal film.. though a few CC used for the non-magnetic properties)

George H.

 

[George Herold]

On Saturday, February 21, 2015 at 8:12:00 AM UTC-5, Baron wrote:

George Herold prodded the keyboard with:

For best results as a detector get the 113R "clear"
sand down most of the plastic till you get near the wire bond
and then polish out the scratches.

George H.

Hi George,
You can flame polish the plastic. Just touch the plastic into a small
flame until it starts to melt, it only takes a couple of seconds or
so. I use this method on the lathe to polish the lens ends on 1/2"
perspex rod.
--
Best Regards:
Baron.

Oh thanks I hadn't thought of that.
(I use a bit of spit as a temporary solution.)

George H.

 

[Baron]

George Herold prodded the keyboard with:

For best results as a detector get the 113R "clear"
sand down most of the plastic till you get near the wire bond
and then polish out the scratches.

George H.

Hi George,
You can flame polish the plastic. Just touch the plastic into a small
flame until it starts to melt, it only takes a couple of seconds or
so. I use this method on the lathe to polish the lens ends on 1/2"
perspex rod.
--
Best Regards:
Baron.

 

[John Doe]

"David Eather" <eather@tpg.com.au> wrote in newsp.xt37nkhawei6gd@phenom-
pc.asus:

On Mon, 16 Feb 2015 04:36:51 +1000, Michael Black <et472@ncf.ca> wrote:

On Sun, 15 Feb 2015, David Eather wrote:

On Sat, 14 Feb 2015 11:49:36 +1000, Michael Black <et472@ncf.ca> 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.

Not so, and by the way all diodes are zener diodes - we just don't
normally run them in the breakdown region.

Yes, all diodes can "zener" but they are reversed biased.


So what?

So shut up and humble yourself, asshole.