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'[TECH]:: Unintended consuences <-- [AR] Rocket Ra'
2008\08\16@032639 by Apptech

face
flavicon
face

Here's a story from the aeronautical world.
As a metaphor for avoiding disaster by outthinking Murphy it
may be useful, and as a story its interesting.



       Russell

__________________________

Randall,
        since you will be trucking your Rocket Racer from
place to place,
a safety tip from the Sailplane world.

It is rather easy to have an error where the controls move
correctly with
the stick but are still not properly attached.
Sailplanes get assembled and disassembled a lot. Some of
them spend the
majority of their lives disassembled in a  trailer.
After re-assembly the sailplane guys do a two person test on
every
disconnected surface.

Person one sits in the cockpit and moves each surface
through two full
range of motion checks.

Person two applies pressure by hand to each surface in  turn
testing for
disconnected movement
in both directions throughout the whole range of motion.

This is to catch something like a ball end in a socket
without the bolt
through.
It moves the surface just fine, but as soon as tension is
placed on the
linkage it pops loose.

Obviously you don't want a gorilla doing the "apply force to
the surface"
test, but you don't want  to miss anything either.

I've personally seen this test fail. I was third or fourth
in line waiting
for a tow with the club glider at warner springs.

The first sailplane in line was a modern sailplane, supposed
to
have  "automatic" connections.
The sailplane had been assembled  by the owner/pilot using
the assembly
dollies that are supposed to allow single person assembly.
The guy marshalling tows asked him if he had done a control
check after
assembly as he was hooking up the tow rope.
The pilot replied yes, the tow guy said "a positive check?"
(as opposed to
a visual view check)
The pilot said no,  the tow guy said no tow, the pilot was
all pissed off
that he was going to loose his place in line,
and started getting mad.  another pilot in line ran up and
said I'll help
you do a quick one....

The right aileron moved up against force, but when   the
check guy applied
pressure in the opposite direction on the second
control cycle the aileron popped free. The pilot turned
ashen white and
became very sheepish.
The tow guy had just saved his life.


Paul



At 06:31 PM 8/14/2008 -0700, you wrote:
{Quote hidden}

_______________________________________________
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'[TECH]:: Unintended consuences <-- [AR] Rocket Rac'
2008\08\16@034708 by Apptech

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> Subject: [TECH]:: Unintended consuences <-- [AR] Rocket
> Racer Question....

===>

Subject: [TECH]:: Unintended consequences <-- [AR] Rocket
Racer Question....


See!
The spilling chicker seems to bee om stryke.



       R

2008\08\16@080812 by Carl Denk

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face
If this is swivel ball and socket "rod end" connection, standard
practice is to have a large diameter washer under the bolt head or nut
to contain the ball and socket if there is wear or otherwise it tries to
become disconnected.

Apptech wrote:
{Quote hidden}


'[OT]Brilliant unintended pun'
2009\07\01@011424 by cdb
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Job agency in NZ is advertising for a Technical Adviser.

.Globally recognised dairy manufacturer.
.Great team culture.

This is almost certainly Fontana who seem to own the dairy market in
NZ. I wonder if they only select the cream of the crop and it's hard
cheese to all those who fail the interview?

Colin
--
cdb,  on 1/07/2009



2009\07\01@011705 by cdb

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face


This is almost certainly Fontana - oops meant Fonterra

Colin
--
cdb,  on 1/07/2009



2009\07\01@013201 by Xiaofan Chen

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On Wed, Jul 1, 2009 at 1:14 PM, cdb<EraseMEcolinspam_OUTspamTakeThisOuTbtech-online.co.uk> wrote:
>  Job agency in NZ is advertising for a Technical Adviser.
>
>  .Globally recognised dairy manufacturer.
>  .Great team culture.
>
> This is almost certainly Fonterra who seem to own the dairy market in
> NZ. I wonder if they only select the cream of the crop and it's hard
> cheese to all those who fail the interview?
>

I understand the meaning of "the cream of the crop" but I failed
to understand what do you mean by "hard cheese". So I asked
a few colleagues here and none of them understood it even though
one of them is really good at English. So I fired up WordWeb and
found it seems to be only used by Brits and mean "bad luck".

Interesting pun.


--
Xiaofan http://mcuee.blogspot.com

2009\07\01@025336 by cdb

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:: but I failed to understand what do you mean by "hard cheese".

:: seems to be only used by Brits

I didn't know that, I thought it was in other English variants. Now I
have a quest to find out other British English only phrases.

Colin
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Hosted by:  http://www.1and1.co.uk/?k_id=7988359







2009\07\01@041658 by Alan B. Pearce

face picon face
>:: but I failed to understand what do you mean by "hard cheese".
>
>:: seems to be only used by Brits
>
>I didn't know that, I thought it was in other English variants.
>Now I have a quest to find out other British English only phrases.

I would class it as being well known in English speaking countries,
specifically those that are part of the British Commonwealth, rather than
US-centric countries.

The term is a bit more than just 'bad luck', it is self induced bad luck,
i.e. you have done something that induced the bad luck situation, although
the way Colin used it, it would be just 'tough luck' rather than 'bad luck'.

I suspect it dates back to the workers going out to harvest, with their
lunch wrapped up. Lunch would typically be bread, cheese and cider. If you
didn't wrap the cheese properly it would go hard, and is then almost
inedible.

2009\07\01@052731 by Xiaofan Chen

face picon face
On Wed, Jul 1, 2009 at 4:16 PM, Alan B. Pearce<@spam@Alan.B.PearceKILLspamspamstfc.ac.uk> wrote:
>>:: but I failed to understand what do you mean by "hard cheese".
>>
>>:: seems to be only used by Brits
>>
>>I didn't know that, I thought it was in other English variants.
>>Now I have a quest to find out other British English only phrases.
>
> I would class it as being well known in English speaking countries,
> specifically those that are part of the British Commonwealth, rather than
> US-centric countries.

Singapore used to be a British colony and is part of British Commonwealth.
http://en.wikipedia.org/wiki/List_of_members_of_the_Commonwealth_of_Nations_by_name

Even Canada is part British Commonwealth. So I am not so sure what
English Speaking Countries qualify as US-centric other than USA.

> The term is a bit more than just 'bad luck', it is self induced bad luck,
> i.e. you have done something that induced the bad luck situation, although
> the way Colin used it, it would be just 'tough luck' rather than 'bad luck'.
>
> I suspect it dates back to the workers going out to harvest, with their
> lunch wrapped up. Lunch would typically be bread, cheese and cider. If you
> didn't wrap the cheese properly it would go hard, and is then almost
> inedible.

Thanks for the explanation.


--
Xiaofan http://mcuee.blogspot.com


'[OT] Unintended Consequences sun powered scu'
2013\11\14@151451 by YES NOPE9
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face
I felt compelled to share what happened this week.........
In the interests of recycling everything , I used the front lens of a projection TV to winterize a window.
The lens is a flat piece of plastic about 3mm thick.  I guess it is a fresnel lens.
I cut it to fit the window and installed it as an additional transparent layer.
I thought nothing of it until today when I happen to look at the stereo receiver sitting near the window.
The top of the receiver and two of the knobs were partially melted.
So now I am removing the plastic.
plus.google.com/u/0/photos/106062573647649373210/albums/5946209076234785857
Gus in Denver
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2013\11\14@155650 by Dom S

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I've seen the same things happen with paperweights and ornaments/vases.

One of my friends actually had a pile of paperwork start smouldering on a sunny day.

Dom


{Original Message removed}

2013\11\14@161955 by IVP

face picon face
> I've seen the same things happen with paperweights and ornaments/
> vases.
>
> One of my friends actually had a pile of paperwork start smouldering
> on a sunny day.

And water bottles in cars

http://tvnz.co.nz/national-news/woman-says-water-bottle-caused-car-fire-5340573

http://www.hoax-slayer.com/car-fire-water-bottle.shtml

Joe

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'[OT] Unintended Consequences sun powered sculpting'
2013\11\14@162836 by John Gardner

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Good Lord...  No good deed goes unpunished, I guess.
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2013\11\14@164932 by RussellMc

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Then there was my previously mention solar-satellite-dish-chair-burner [tm]

Large: g3.img-dpreview.com/3F7339A620EB4831BDD333E8DF455769.jpg
Small:  http://g1.img-dpreview.com/25740F9934B4450CACE1DF2F6BCE0C63.jpg

Satellite dish was dual re-purposed.

- Trial solar concentrator with Al / Mylar foil
- Cellphone range extender.

Was used in latter mode t night sitting in old chair on back porch. Used to
get reliable coverage as phone coverage in our area was in a "shadow" from
local ridge.

Dish left sitting on chair arm.
Sun rose. Low angle of morning sun produced result which seemed infeasible
[tm] due to orientation.
Could easily have burned house down! :-(.


   Russell



On 15 November 2013 04:14, YES NOPE9 <KILLspamyesKILLspamspamnope9.com> wrote:

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'[OT] Unintended Consequences sun powered scu'
2013\11\14@182835 by Joe Wronski

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Rather than tearing out the lens, it might have been better to move the stereo and replace it with something that stores the thermal energy during the day and releases it later.  A brick?

Joe W


On 11/14/2013 03:14 PM, YES NOPE9 wrote:
{Quote hidden}

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Stillwater Embedded Engineering
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'[OT] Unintended Consequences sun powered sculpting'
2013\11\15@044049 by alan.b.pearce

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You are doing on a small scale, here in the UK we do it on a large scale ....

http://www.dailymail.co.uk/news/article-2410972/Walkie-Talkie-building-Walkie-Scorchie-skyscraper-firm-scaffolding-protect-nearby-shops.html


Melted plastic wing mirrors on cars, bubbled paint work, and all sorts of other damage ...



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2013\11\15@082952 by Adam Field

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>> On 15 November 2013 04:14, YES NOPE9 <spamBeGoneyesspamBeGonespamnope9.com> wrote:
>>
>> > I felt compelled to share what happened this week.........
>> > In the interests of recycling everything , I used the front lens of a
>> > projection TV to winterize a window.
>> > The lens is a flat piece of plastic about 3mm thick.  I guess it is a
>> > fresnel lens.
>> > I cut it to fit the window and installed it as an additional
>> > transparent layer.
>> > I thought nothing of it until today when I happen to look at the
>> > stereo receiver sitting near the window.
>> > The top of the receiver and two of the knobs were partially melted.
>> > So now I am removing the plastic.
>> >

Good idea, those TV lenses can really start fires. I'm glad you just
got away with a melted case.

http://www.youtube.com/watch?v=XFw7U7V1Hok
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2013\11\15@140555 by Bob Blick

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On Fri, Nov 15, 2013, at 05:29 AM, Adam Field wrote:
> Good idea, those TV lenses can really start fires. I'm glad you just
> got away with a melted case.
>
> http://www.youtube.com/watch?v=XFw7U7V1Hok

ooh, great idea, I know where I'm going on my lunch hour:

http://sfbay.craigslist.org/sby/zip/4183872872.html

Just kidding, I don't like barbeque _that_ much :)

-- http://www.fastmail.fm - Does exactly what it says on the tin

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2013\11\15@211139 by c h

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> You are doing on a small scale, here in the UK we do it on a large scale
....
>
>
http://www.dailymail.co.uk/news/article-2410972/Walkie-Talkie-building-Walkie-Scorchie-skyscraper-firm-scaffolding-protect-nearby-shops.html
>

Folks in USA got the thing on somewhat greater scale, actually.  The
similar kind of "moving hot spot" beneath the continent is believed by many
to melt out the Snake River Plain  :-)
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2013\11\15@215749 by Joe Wronski

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I've also seen stories of melted vinyl siding on 3-deckers[1] that are next door to others that installed the newer thermal windows (I forget the term for the glass).

[1] 3-decker might be a local term in Worcester MA area.  They're 3 story apartment buildings on a quarter acre of land and they're really close together.

Joe W


On 11/15/2013 9:11 PM, c h wrote:
>> You are doing on a small scale, here in the UK we do it on a large scale
> ...
>>
> www.dailymail.co.uk/news/article-2410972/Walkie-Talkie-building-Walkie-Scorchie-skyscraper-firm-scaffolding-protect-nearby-shops.html
> Folks in USA got the thing on somewhat greater scale, actually.  The
> similar kind of "moving hot spot" beneath the continent is believed by many
> to melt out the Snake River Plain  :-)


-- Joe Wronski
TakeThisOuTjwronskiEraseMEspamspam_OUTstillwatereng.net
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2013\11\16@155444 by Al Shinn

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Years ago, while walking past an East facing shop window I noticed a display with several magnifying glasses and piles of autumn leaves, all set up for a conflagration. I stepped in and made some helpful suggestions.
{Quote hidden}

Looking forward,
Al Shinn
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'[EE] TL431 as unintended oscillator'
2017\04\28@193451 by Bob Blick
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part 1 561 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

I am attaching a portion of a circuit that forms a battery indicator. It uses a TL431 as a YES/NO battery indicator activating an LED. It does not oscillate, but it does have a bit of gain to any low-to-medium frequency ripple on the power line. Should I go to the extra expense of adding a small capacitor from reference terminal to cathode? Adding one definitely shuts it up. Perhaps I should try to squeeze room for one and leave it unpopulated in the first board run.

Thanks in advance for any feedback,

Bob

part 2 2912 bytes content-type:image/gif; name="BatIndicator.gif" (decode)


part 3 197 bytes content-type:text/plain; name="ATT00001.txt"
(decoded base64)

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2017\04\28@220833 by RussellMc

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On 29 April 2017 at 11:34, Bob Blick <EraseMEbobblickspamoutlook.com> wrote:

> I am attaching a portion of a circuit that forms a battery indicator. It
> uses a TL431 as a YES/NO battery indicator activating an LED. It does not
> oscillate, but it does have a bit of gain to any low-to-medium frequency
> ripple on the power line. Should I go to the extra expense of adding a
> small capacitor from reference terminal to cathode? Adding one definitely
> shuts it up. Perhaps I should try to squeeze room for one and leave it
> unpopulated in the first board run.
>

​They can definitely be made to oscillate (as you know) but I've not had
them do ​so in practice.

In your circuit, if the input was "stiff" you would not get oscillation as
there is then no feedback path.
To oscillate the LED drain has to drop the supply enough to take Vref
across the thrteshold again.
Adding a small amount of hystersis would make sure of the result.

Adding a cap to Vref can help BUT can also enhance ods of oscillation as if
I_LED_on drops supply significantly the cap will hold Vrf hi for about R3.C
and then lower Vref enough to turn LED off. ie it lowers Fosc. This can be
a "feature"  with flashing indicator at critical point :-).
This could be induced if R5 not used (see below) by adding a small R on Vin
side of 1k2 and taking ref divider to it, so I_LED_on DOES drop ref enough
to cause oscillation :-).

Vin high - LED on
Vin marginal - LED flashes
Vin low - LED off


Other:

I'm not sure why R5 is present - perhaps to ensure leakage current does not
make the LED glimmer - but TL431 off current is extremely low.
If not needed it would make room for a capacitor elsewhere.


R
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2017\04\29@072346 by Clint Jay

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A tidbit of trivia, I have in my time repaired thousands of SMPSUs and they
almost all had a TL431. My diagnostic tool of choice was/is the component
tester on a Hameg 'scope and I can instantly recognise a fault TL because a
working one produces a rather pretty junction with an umbrella above (or
below depending on probe polarity), I believe this is because they
oscillate when a fairly slow AC signal is applied

On 29 Apr 2017 12:35 am, "Bob Blick" <RemoveMEbobblickEraseMEspamEraseMEoutlook.com> wrote:

I am attaching a portion of a circuit that forms a battery indicator. It
uses a TL431 as a YES/NO battery indicator activating an LED. It does not
oscillate, but it does have a bit of gain to any low-to-medium frequency
ripple on the power line. Should I go to the extra expense of adding a
small capacitor from reference terminal to cathode? Adding one definitely
shuts it up. Perhaps I should try to squeeze room for one and leave it
unpopulated in the first board run.

Thanks in advance for any feedback,

Bob
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2017\04\29@102708 by RussellMc

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On 29 April 2017 at 23:23, Clint Jay <RemoveMEcjaysharpspam_OUTspamKILLspamgmail.com> wrote:

> A tidbit of trivia, I have in my time repaired thousands of SMPSUs and they
> almost all had a TL431. My diagnostic tool of choice was/is the component
> tester on a Hameg 'scope and I can instantly recognise a fault TL because a
> working one produces a rather pretty junction with an umbrella above (or
> below depending on probe polarity), I believe this is because they
> oscillate when a fairly slow AC signal is applied
>
> ​It seems likely that the oscillation you see is an intended property of
the overall SMPS circuit rather than the TL431 (although there is no doubt
that it could add its own magic as well.)

A typical volatage controlled SMPS which is "in control" hunts perpetually
around the target voltage unless extra effort has been made in the design
to not do so.It would be possible to eg try and hold the power switch at a
duty cycle that produced a Vout eg just above the TL431 switch point for
curremt load and Vin, but this then loses one direction of control - the
added control loop has to ensure Vout does not wander high by using only
input side information. While this would be possible I can see no point in
doing so in most cases - so that the TL431 will then be forced to oscillate
at a rate set by hysteresis, load and output reservoir capacity (at least
:-) ).


    Russell
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2017\04\29@131328 by Clint Jay

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Nope, I understand what you're saying but they exhibit the same behaviour
out of circuit.

On 29 Apr 2017 3:27 pm, "RussellMc" <RemoveMEapptechnzTakeThisOuTspamspamgmail.com> wrote:

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'[EE] TL431 as unintended oscillator'
2017\05\02@113754 by Bob Blick
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R5 is indeed there to prevent LED glimmer, although it is also needed to bring the TL431 into voltage spec.

The glimmer is an issue depending on the brand of TL431 used. All the "name brands" consume about 300uA, which is enough to light an LED indoors. The TL431 that I buy for a penny apiece (unisonic and worse) only draw about 60uA, but they won't be used in this application.

I thrashed this circuit a bit and never got it to actually oscillate so I am leaving it as in.

Thanks for your help.

Best regards,
Bob

________________________________________
From: RemoveMEpiclist-bouncesKILLspamspammit.edu <piclist-bouncesSTOPspamspamspam_OUTmit.edu> on behalf of RussellMc
Sent: Friday, April 28, 2017 7:07 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] TL431 as unintended oscillator

On 29 April 2017 at 11:34, Bob Blick <spamBeGonebobblickSTOPspamspamEraseMEoutlook.com> wrote:

> I am attaching a portion of a circuit that forms a battery indicator. It
> uses a TL431 as a YES/NO battery indicator activating an LED. It does not
> oscillate, but it does have a bit of gain to any low-to-medium frequency
> ripple on the power line. Should I go to the extra expense of adding a
> small capacitor from reference terminal to cathode? Adding one definitely
> shuts it up. Perhaps I should try to squeeze room for one and leave it
> unpopulated in the first board run.
>

​They can definitely be made to oscillate (as you know) but I've not had
them do ​so in practice.

In your circuit, if the input was "stiff" you would not get oscillation as
there is then no feedback path.
To oscillate the LED drain has to drop the supply enough to take Vref
across the thrteshold again.
Adding a small amount of hystersis would make sure of the result.

Adding a cap to Vref can help BUT can also enhance ods of oscillation as if
I_LED_on drops supply significantly the cap will hold Vrf hi for about R3.C
and then lower Vref enough to turn LED off. ie it lowers Fosc. This can be
a "feature"  with flashing indicator at critical point :-).
This could be induced if R5 not used (see below) by adding a small R on Vin
side of 1k2 and taking ref divider to it, so I_LED_on DOES drop ref enough
to cause oscillation :-).

Vin high - LED on
Vin marginal - LED flashes
Vin low - LED off


Other:

I'm not sure why R5 is present - perhaps to ensure leakage current does not
make the LED glimmer - but TL431 off current is extremely low.
If not needed it would make room for a capacitor elsewhere.

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2017\05\03@095209 by RussellMc

face picon face

On 3 May 2017 at 03:37, Bob Blick <KILLspambobblickspamBeGonespamoutlook.com> wrote:

> R5 is indeed there to prevent LED glimmer, although it is also needed to
> bring the TL431 into voltage spec.
>

​When the TL431 is off it is subject to full Vin, so I can't see how iR5
affects voltage spec.
(Which is not to say it doesn't, I just don't know why - maybe related to
unseen parts of the circuit.

A TL431 or TLV431 nominally have V_Cathode min = Vref but in practice the
will pull down to about 1 diode drop below that - ie until the internal
ref-Cathodediode becomes forward biased.
TL431 are usually spcd at Vmax of 36V more or less and T:V431 to about half
that.
Some Chinese TLV431 equivalent have a data sheet rating of 30V+ but that
may be due to lax datasheet updating on reuse.

300 uA and 60 uA sound like the ​minimum Cathode current for regulation.
When off Icathode is usually well under 1 uA.
I'd have thoughtthat when properly off glimmer would be negligible.
(Say 1 uA x 2.5V = 2.5 uW or about say 0.5 milli-lumen.
Illuminating say 10mm square = 10^-4 m^2 so about 5 lux +/- N00% :-)
So maybe perhaps visible as a change of tone in dim conditions.
Such calculations are worse than magic or dice throwing in practice :-).


Typical TL431 are about 300 uA as you say. Zetex devices (now Diodes Inc)
are much lower.


​ Russell​
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