When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I found that they didn't have even a reasonably sharp knee, behaving more like LEDs in forward mode, maybe worse. Do I remember correctly? Are they still the same?
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
Am 08.10.24 um 11:24 schrieb Pimpom:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
yes, that's true. At > 5V they are really avalanche diodes. Around 5-7V
it is a mix. Zeners & avalanche diodes have a different TC, and it >compensates at around 6V.
You can see the onset of avalanche behavior in the noise spectrum with
rising voltage. True Zeners are much better here. For the BZX84 family:
< >https://www.flickr.com/photos/137684711@N07/24411798996/in/album-72157662535945536
>
Prof. Zener even sued the industry not to use his name for avalanche
thingies because it was not "his" effect. They settled on Z-Diodes
pretending it was for the V/I curve. But in the end the ghost was out of
the bottle.
Gerhard
On 2024-10-08 11:24, Pimpom wrote:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I found that they didn't have even a reasonably sharp knee, behaving more like LEDs in forward mode, maybe worse. Do I remember correctly? Are they still the same?
Often, below 3V3, they were just a series chain of normal diodes.
Nowadays a LED, with a sharp knee, works better if the voltage matches.
Just beware using them at very low currents - they are light sensitive.
Arie
On Tue, 8 Oct 2024 11:46:04 +0200, Arie de Muijnck <noreply@ademu.nl>
wrote:
On 2024-10-08 11:24, Pimpom wrote:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I found that they didn't have even a reasonably sharp knee, behaving more like LEDs in forward mode, maybe worse. Do I remember correctly? Are they still the same?
Often, below 3V3, they were just a series chain of normal diodes.
Nowadays a LED, with a sharp knee, works better if the voltage matches.
Just beware using them at very low currents - they are light sensitive.
Arie
An LED and a bipolar transistor and a source resistor can make a
near-zero tempco current source. With free light!
On a sunny day (Tue, 8 Oct 2024 14:54:39 +0530) it happened Pimpom <Pimpom@invalid.invalid> wrote in <sT6NO.84691$Xx4a.59580@fx11.ams1>:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
Yes.
These days there are 'bandgap' references, those are about 1.25V,
extr3mely stable.
https://en.wikipedia.org/wiki/Bandgap_voltage_reference
You can also use a chip like TL431 (google TL431.pdf)
to make a reference from about 2.5 V upwards
to whatever you like with 2 resistors as voltage devider.
IIRC it uses that bandgap reference principle.
https://en.wikipedia.org/wiki/TL431#Applications
On Tue, 8 Oct 2024 14:54:39 +0530, Pimpom <Pimpom@invalid.invalid>
wrote:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
Yup. Soft knees and terrible tempcos.
Bandgaps like LM4040 are great. They get down to 0.1% and 50 PPM/deg
C. 1.2 to 5 volts.
On 08-10-2024 07:25 pm, Jan Panteltje wrote:
On a sunny day (Tue, 8 Oct 2024 14:54:39 +0530) it happened PimpomI have a bunch of TL431, LM385 (1.25, 2.5 & adj.) and LM4040 references.
<Pimpom@invalid.invalid> wrote in <sT6NO.84691$Xx4a.59580@fx11.ams1>:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
Yes.
These days there are 'bandgap' references, those are about 1.25V,
extr3mely stable.
https://en.wikipedia.org/wiki/Bandgap_voltage_reference
You can also use a chip like TL431 (google TL431.pdf)
to make a reference from about 2.5 V upwards
to whatever you like with 2 resistors as voltage devider.
IIRC it uses that bandgap reference principle.
https://en.wikipedia.org/wiki/TL431#Applications
But somehow these high precision, high stability references somehow feel
like overkill in certain situations. It's not the cost, it's the >appropriateness.
I remember the first time I used an LM385. I live in a very remote, very >hilly part of India. 30-40 years ago, most of the rural areas in my
state was powered by 300kVA diesel generators. The generators were made
by an Indian company but the voltage regulators were imported and cost
the then equivalent of about US$4-5000 to replace. Moreover, the
manufacturer sometimes took months to supply a replacement.
So I designed and made several units for the state power agency, using
only readily available parts. That's where I used LM385s as the
reference. I had to make some of the parts by hand - like the EMI
filter, the box, PCB, etc. The only material available then for weather >proofing was small tubes of Araldite epoxy intended for domestic
consumer use.
On Tue, 8 Oct 2024 12:08:20 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:
Am 08.10.24 um 11:24 schrieb Pimpom:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
yes, that's true. At > 5V they are really avalanche diodes. Around 5-7V
it is a mix. Zeners & avalanche diodes have a different TC, and it
compensates at around 6V.
You can see the onset of avalanche behavior in the noise spectrum with
rising voltage. True Zeners are much better here. For the BZX84 family:
<
https://www.flickr.com/photos/137684711@N07/24411798996/in/album-72157662535945536
>
Prof. Zener even sued the industry not to use his name for avalanche
thingies because it was not "his" effect. They settled on Z-Diodes
pretending it was for the V/I curve. But in the end the ghost was out of
the bottle.
Gerhard
Everybody calls them all zeners now.
You can actually get a zener to oscillate.
https://www.dropbox.com/scl/fi/uvbj2tmrlitfv233ncamr/Zener_Noise.pdf?rlkey=bqxynlx8g1r6b6cfiimfaejuo&raw=1
Expensive noise diodes are probably just selected zeners.
On 08-10-2024 07:25 pm, Jan Panteltje wrote:
On a sunny day (Tue, 8 Oct 2024 14:54:39 +0530) it happened PimpomI have a bunch of TL431, LM385 (1.25, 2.5 & adj.) and LM4040 references.
<Pimpom@invalid.invalid> wrote in <sT6NO.84691$Xx4a.59580@fx11.ams1>:
When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?
Yes.
These days there are 'bandgap' references, those are about 1.25V,
extr3mely stable.
https://en.wikipedia.org/wiki/Bandgap_voltage_reference
You can also use a chip like TL431 (google TL431.pdf)
to make a reference from about 2.5 V upwards
to whatever you like with 2 resistors as voltage devider.
IIRC it uses that bandgap reference principle.
https://en.wikipedia.org/wiki/TL431#Applications
But somehow these high precision, high stability references somehow feel
like overkill in certain situations. It's not the cost, it's the >appropriateness.
I remember the first time I used an LM385. I live in a very remote, very >hilly part of India.
On Wed, 9 Oct 2024 01:40:46 +0530, Pimpom <Pimpom@invalid.invalid>
wrote:
I remember the first time I used an LM385. I live in a very remote, very
hilly part of India.
Sounds interesting. What are the coordinates?
On 09-10-2024 08:22 pm, john larkin wrote:
On Wed, 9 Oct 2024 01:40:46 +0530, Pimpom <Pimpom@invalid.invalid>......<snip>..........
wrote:
My house is at about 23.723°N 92.7173°E which is on the southern side of the state capital, a city of about 300K. The state is one twentieth the
I remember the first time I used an LM385. I live in a very remote, very >>> hilly part of India.
Sounds interesting. What are the coordinates?
size of California, sandwiched along most of its north-south length
between Bangladesh on the west and Burma to the east.
Most of the state is on steep hillsides, with few flat and level areas.
The aerial distance to the sole airport in the state is about 14km and
31km by road. It used to be 43km before they found a way to bypass the
worst parts.
Indigenous people make up roughly 90% of the population and have little
in common with mainstream India.
Pimpom <Pimpom@invalid.invalid> wrote:
On 09-10-2024 08:22 pm, john larkin wrote:
On Wed, 9 Oct 2024 01:40:46 +0530, Pimpom <Pimpom@invalid.invalid>......<snip>..........
wrote:
My house is at about 23.723°N 92.7173°E which is on the southern side of >> the state capital, a city of about 300K. The state is one twentieth the
I remember the first time I used an LM385. I live in a very remote, very >>>> hilly part of India.
Sounds interesting. What are the coordinates?
size of California, sandwiched along most of its north-south length
between Bangladesh on the west and Burma to the east.
Most of the state is on steep hillsides, with few flat and level areas.
The aerial distance to the sole airport in the state is about 14km and
31km by road. It used to be 43km before they found a way to bypass the
worst parts.
Indigenous people make up roughly 90% of the population and have little
in common with mainstream India.
Ah, so you’re one of those guys who used to come down from the hills and take over Burma periodically, the way the Elamites and Medes did to Sumer. Glad to know. ;)
Cheers
Phil Hobbs
On 09-10-2024 08:22 pm, john larkin wrote:
On Wed, 9 Oct 2024 01:40:46 +0530, Pimpom <Pimpom@invalid.invalid>......<snip>..........
wrote:
My house is at about 23.723°N 92.7173°E which is on the southern side of
I remember the first time I used an LM385. I live in a very remote, very >>> hilly part of India.
Sounds interesting. What are the coordinates?
the state capital, a city of about 300K. The state is one twentieth the
size of California, sandwiched along most of its north-south length
between Bangladesh on the west and Burma to the east.
Most of the state is on steep hillsides, with few flat and level areas.
The aerial distance to the sole airport in the state is about 14km and
31km by road. It used to be 43km before they found a way to bypass the
worst parts.
Indigenous people make up roughly 90% of the population and have little
in common with mainstream India.
On 10-10-2024 01:07 am, Phil Hobbs wrote:
Pimpom <Pimpom@invalid.invalid> wrote::) :) Maybe we should do it again and kick out the military junta there.
On 09-10-2024 08:22 pm, john larkin wrote:
On Wed, 9 Oct 2024 01:40:46 +0530, Pimpom <Pimpom@invalid.invalid>......<snip>..........
wrote:
My house is at about 23.723°N 92.7173°E which is on the southern side of >>> the state capital, a city of about 300K. The state is one twentieth the
I remember the first time I used an LM385. I live in a very remote, very >>>>> hilly part of India.
Sounds interesting. What are the coordinates?
size of California, sandwiched along most of its north-south length
between Bangladesh on the west and Burma to the east.
Most of the state is on steep hillsides, with few flat and level areas.
The aerial distance to the sole airport in the state is about 14km and
31km by road. It used to be 43km before they found a way to bypass the
worst parts.
Indigenous people make up roughly 90% of the population and have little
in common with mainstream India.
Ah, so you’re one of those guys who used to come down from the hills and
take over Burma periodically, the way the Elamites and Medes did to Sumer. >> Glad to know. ;)
Cheers
Phil Hobbs
It wasn't too long ago that my people were headhunters! The state - with
its 1 million citizens - is again being flooded by thousands of refugees
from Burma fleeing the poverty and oppression in their own country.
I say 'again' because it was like this for decades before their brief
stint with democracy. We give them shelter, food and employment, even ad
hoc schools. They reward us with a sharp rise in crime - drugs, murder, >robbery, scams, rape, human trafficking......
26 years ago, I went along with some friends to see the Governor about >establishing a municipality here. The talk diverged to other topics and
the Governor - a retired military officer appointed by the central
Indian government - said that 98& of all crimes in the state were
committed by these illegal immigrants from Burma. My own estimate had
been 85-90%.
On Thu, 10 Oct 2024 00:47:58 +0530, Pimpom <Pimpom@invalid.invalid>
wrote:
Most of the state is on steep hillsides, with few flat and level areas.
The aerial distance to the sole airport in the state is about 14km and
31km by road. It used to be 43km before they found a way to bypass the
worst parts.
Indigenous people make up roughly 90% of the population and have little
in common with mainstream India.
Lots of motorcycles driving on the wrong side of the street.
Looks like fun, riding on those hilly streets.
San Francisco is hilly too. Kamakazies skateboard down the hills.
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