Driver to drive?

[Phil Hobbs]

On 2020-02-02 03:28, Klaus Kragelund wrote:

My product is 20x20x20 cm

I live in Denmark and the last couple of years we have had extremely
mild winters, averaged 5.4 degrees in January, a all time record

https://www.dr.dk/nyheder/viden/klima/varmeste-januar-nogensinde-er-det-klimaforandringernes-skyld

So I need a chamber that works a room temperature

Cheers

Klaus

A beer fridge for the chamber, a resistive heater, and a jug of liquid
CO2 for cooling. Back when I was a real RF engineer, we had an
environmental chamber that worked like that. Round here you can get
your CO2 at a sporting goods store that sells paintball gear.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Klaus Kragelund]

On Sunday, February 2, 2020 at 3:37:03 PM UTC+1, upsid...@downunder.com wrote:

On Sat, 1 Feb 2020 09:03:47 -0800 (PST), Klaus Kragelund
klauskvik@hotmail.com> wrote:

Hi

I am working on something for my own business

So need to do testing at below 0 degrees C

What would be a cheapskate way to do it?

Just a household freezer?

Product is just 20x20x20

There are some issues with electronics in cold temperatures.

One problem with any processor based (or sequentially logic) system
is starting the clock oscillator at extreme low temperatures. This can
be quite unreliable. Once the clock is running, the electronics will
generate some internal heat warming the components in the box to
higher temperatures. Thus, even i some components are initially out of
specs it will be within specs after a while.

When doing cold testing, let the device cool to the lowest
temperature obtainable with equipment power turned off. Once the
lowest temperature has been achieved, turn equipment power on and
verify that the clock starts. Once running, make sure the box outside
temperature remains in your case at -20 C despite the 5 W heating,

We have big, super expensive chambers at work, where we always do that LOL and UOL (Lower Operating Limit and Upper Operating Limit), which has the purpose you mention to find when it really fails. We would normally have the LOL at -50 and UOL at 150. But for my own business if I can do a minus 20 test and 150 then I feel pretty safe

When doing indoor cool chamber tests, the initial air contains some
absolute humidity. While the chamber cools down, the relative humidity
RH increases, finally reaching 100 %, after which condensation or
frost will accumulate. Do not put the equipment directly on the bottom
of the chamber, since there might be some condensation water on the
bottom. The condensation or frost may cause problems with uncoated
PCBs.

Yes. Also, don't open the chamber when at -40, tried that, won't do it again (heavy condensation)

Cheers

Klaus

 

Klaus Kragelund <klauskvik@hotmail.com> wrote in
news:484e78ef-6290-493c-bbd0-7c6bfe76e4a0@googlegroups.com:

On Sunday, February 2, 2020 at 3:37:03 PM UTC+1,
upsid...@downunder.com wrote:
On Sat, 1 Feb 2020 09:03:47 -0800 (PST), Klaus Kragelund
klauskvik@hotmail.com> wrote:

Hi

I am working on something for my own business

So need to do testing at below 0 degrees C

What would be a cheapskate way to do it?

Just a household freezer?

Product is just 20x20x20

There are some issues with electronics in cold temperatures.

One problem with any processor based (or sequentially logic)
system is starting the clock oscillator at extreme low
temperatures. This can be quite unreliable. Once the clock is
running, the electronics will generate some internal heat
warming the components in the box to higher temperatures. Thus,
even i some components are initially out of specs it will be
within specs after a while.

When doing cold testing, let the device cool to the lowest
temperature obtainable with equipment power turned off. Once the
lowest temperature has been achieved, turn equipment power on and
verify that the clock starts. Once running, make sure the box
outside temperature remains in your case at -20 C despite the 5 W
heating,

We have big, super expensive chambers at work, where we always do
that LOL and UOL (Lower Operating Limit and Upper Operating
Limit), which has the purpose you mention to find when it really
fails. We would normally have the LOL at -50 and UOL at 150. But
for my own business if I can do a minus 20 test and 150 then I
feel pretty safe

When doing indoor cool chamber tests, the initial air contains
some absolute humidity. While the chamber cools down, the
relative humidity RH increases, finally reaching 100 %, after
which condensation or frost will accumulate. Do not put the
equipment directly on the bottom of the chamber, since there
might be some condensation water on the bottom. The condensation
or frost may cause problems with uncoated PCBs.


Yes. Also, don't open the chamber when at -40, tried that, won't
do it again (heavy condensation)

Cheers

Klaus

Place the UUT in a Fluorinert bath.

I wanted to do an entire motherbaord that way and go down below and
clock up above what the OC boys do. Some of the videos are amusing
watching some dude pouring LN2 over a CPU.

My solution <sic> would work, and for long term too, not "I OC'd my
PC to 10GHz" (for 1 minute long enough to run the benchmark). It is
funny watching them make claims. My PC in a fish tank method would
work down to -70°C with FC-72 Fluorinert. And run... all day.

 

On Sun, 2 Feb 2020 12:24:15 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

On Sunday, February 2, 2020 at 3:37:03 PM UTC+1, upsid...@downunder.com wrote:
On Sat, 1 Feb 2020 09:03:47 -0800 (PST), Klaus Kragelund
klauskvik@hotmail.com> wrote:

Hi

I am working on something for my own business

So need to do testing at below 0 degrees C

What would be a cheapskate way to do it?

Just a household freezer?

Product is just 20x20x20

There are some issues with electronics in cold temperatures.

<clip>

When doing indoor cool chamber tests, the initial air contains some
absolute humidity. While the chamber cools down, the relative humidity
RH increases, finally reaching 100 %, after which condensation or
frost will accumulate. Do not put the equipment directly on the bottom
of the chamber, since there might be some condensation water on the
bottom. The condensation or frost may cause problems with uncoated
PCBs.

When it is cold outside, the outside air dew point and absolute
humidity is low too. When heating indoor air to +20 C the dew point
and absolute humidity remains the same, but the relative humidity
drops to perhaps 30-40 %. When starting an indoor cold chamber the
chamber temperature can sink to outdoor air temperatures and even
lower before the dew point is reached and condensation starts. To
avoid some of the condensation problems, do the test on a day with low
outdoor temperatures, the dew point will be even lower.


>Yes. Also, don't open the chamber when at -40, tried that, won't do it again (heavy condensation)

;-)

 

On Monday, 3 February 2020 04:12:45 UTC, upsid...@downunder.com wrote:

Yes. Also, don't open the chamber when at -40, tried that, won't do it again (heavy condensation)

Also, don't leave a pile of Li batteries in the chamber and accidentally
set it to +150degC.
John

 

[Phil Hobbs]

On 2020-02-04 09:58, George Herold wrote:

Hi all, So another crazy idea of a project/ physics lab. I went looking
on the web for a decent resource.. couldn't find one, so I made a little
intro here,
https://www.dropbox.com/s/91fd1gcswzxh416/hbt1.txt?dl=0
(I'm a little confused about some of the math, so hand-wavy)
One could observe HBT in two ways. Either excess noise in a single
detector (above shot noise) or correlations in the noise with
two detectors.
The idea is to use a laser diode run below threshold as the light
source*. I did this measurement ~10 years ago, and at ~10% below
threshold, I saw enough photo-current such that the wave noise
would be about 10% of the shot noise.
If I did all the numbers right!???

So that's the first thing to check.
Get a laser diode and measure photo-current at proper distance
away, and then measure BW (of diode).

If that looks OK then full speed ahead! I should be able to
get something up and running in ~six months?

I've go a bunch of ideas I'd like to talk about.. But first
a laser diode (750- 900 nm?) and a PD.

George H.

*I talked with this a bit with Phil H. He was concerned
that a laser diode is not a thermal source... which very well might
be right... (I need to do the experiment.)
I tried to do this measurement (excess noise, single detector)
with a Rb discharge lamp, small iris, and PD detector.
There just wasn't enough light. (According to Bloom and Bell,
(first guys to write about Rb lamps) when run at maximum light
The intensity is such that each Rb atom within one optical
path length of the surface emits one photon per Rb lifetime.
So I'm hoping the laser diode with photons created all along
it's length will have enough.

If you plot a 2-D histogram (aka constellation plot for comms guys) of
the probability of measurement vs I and Q amplitude components of laser
light, the results are very different from thermal light.

In thermal light, I and Q are statistically independent, so you get a
2-D Gaussian peak centred around the origin in the constellation plot.

In laser light, the pumping rate constrains sqrt(I**2 + Q**2) to be
nearly constant. Thus the constellation plot is a mildly funny annulus,
essentially zero at the origin.

Goodman's "Statistical Optics" has a plot of this someplace. I'm
currently coming to you from sunny Anna Maria, Florida, which is EOI
South till the end of the month, and Amazon doesn't have a 'search
inside' for the book.

(By the way, I take full credit for the warm winter in the NE--I booked
this place back in July.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[George Herold]

On Tuesday, February 4, 2020 at 10:59:11 AM UTC-5, Phil Hobbs wrote:

On 2020-02-04 09:58, George Herold wrote:
Hi all, So another crazy idea of a project/ physics lab. I went looking
on the web for a decent resource.. couldn't find one, so I made a little
intro here,
https://www.dropbox.com/s/91fd1gcswzxh416/hbt1.txt?dl=0
(I'm a little confused about some of the math, so hand-wavy)
One could observe HBT in two ways. Either excess noise in a single
detector (above shot noise) or correlations in the noise with
two detectors.
The idea is to use a laser diode run below threshold as the light
source*. I did this measurement ~10 years ago, and at ~10% below
threshold, I saw enough photo-current such that the wave noise
would be about 10% of the shot noise.
If I did all the numbers right!???

So that's the first thing to check.
Get a laser diode and measure photo-current at proper distance
away, and then measure BW (of diode).

If that looks OK then full speed ahead! I should be able to
get something up and running in ~six months?

I've go a bunch of ideas I'd like to talk about.. But first
a laser diode (750- 900 nm?) and a PD.

George H.

*I talked with this a bit with Phil H. He was concerned
that a laser diode is not a thermal source... which very well might
be right... (I need to do the experiment.)
I tried to do this measurement (excess noise, single detector)
with a Rb discharge lamp, small iris, and PD detector.
There just wasn't enough light. (According to Bloom and Bell,
(first guys to write about Rb lamps) when run at maximum light
The intensity is such that each Rb atom within one optical
path length of the surface emits one photon per Rb lifetime.
So I'm hoping the laser diode with photons created all along
it's length will have enough.


If you plot a 2-D histogram (aka constellation plot for comms guys) of
the probability of measurement vs I and Q amplitude components of laser
light, the results are very different from thermal light.

In thermal light, I and Q are statistically independent, so you get a
2-D Gaussian peak centred around the origin in the constellation plot.

In laser light, the pumping rate constrains sqrt(I**2 + Q**2) to be
nearly constant. Thus the constellation plot is a mildly funny annulus,
essentially zero at the origin.

Goodman's "Statistical Optics" has a plot of this someplace. I'm
currently coming to you from sunny Anna Maria, Florida, which is EOI
South till the end of the month, and Amazon doesn't have a 'search
inside' for the book.

(By the way, I take full credit for the warm winter in the NE--I booked
this place back in July.)

Enjoy the warmth. It's rainy, 35F and muddy here.
(~freezing point of water and 100% humidity is my least favorite
weather.)
I've got an e-version of Goldman's book.. I'll give it a look see.
Any hints on where or what to look for?

I'm mostly confused when it comes to photon statistics.
So I and Q.. you are looking at 'noise' from the light source at one
frequency and two (orthogonal) phases?...
How hard is that to do? A picture of the set up would help
a lot with my understanding. :^)


George H.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Michael Terrell]

On Tuesday, February 4, 2020 at 10:59:11 AM UTC-5, Phil Hobbs wrote:

If you plot a 2-D histogram (aka constellation plot for comms guys) of
the probability of measurement vs I and Q amplitude components of laser
light, the results are very different from thermal light.

In thermal light, I and Q are statistically independent, so you get a
2-D Gaussian peak centered around the origin in the constellation plot.

In laser light, the pumping rate constrains sqrt(I**2 + Q**2) to be
nearly constant. Thus the constellation plot is a mildly funny annulus,
essentially zero at the origin.

Goodman's "Statistical Optics" has a plot of this someplace. I'm
currently coming to you from sunny Anna Maria, Florida, which is EOI
South till the end of the month, and Amazon doesn't have a 'search
inside' for the book.

(By the way, I take full credit for the warm winter in the NE--I booked
this place back in July.)

Cheers

Phil Hobbs

You aren't far from me or John Fields.

 

[Phil Hobbs]

On 2020-02-04 12:38, George Herold wrote:

On Tuesday, February 4, 2020 at 10:59:11 AM UTC-5, Phil Hobbs wrote:
On 2020-02-04 09:58, George Herold wrote:
Hi all, So another crazy idea of a project/ physics lab. I went looking
on the web for a decent resource.. couldn't find one, so I made a little
intro here,
https://www.dropbox.com/s/91fd1gcswzxh416/hbt1.txt?dl=0
(I'm a little confused about some of the math, so hand-wavy)
One could observe HBT in two ways. Either excess noise in a single
detector (above shot noise) or correlations in the noise with
two detectors.
The idea is to use a laser diode run below threshold as the light
source*. I did this measurement ~10 years ago, and at ~10% below
threshold, I saw enough photo-current such that the wave noise
would be about 10% of the shot noise.
If I did all the numbers right!???

So that's the first thing to check.
Get a laser diode and measure photo-current at proper distance
away, and then measure BW (of diode).

If that looks OK then full speed ahead! I should be able to
get something up and running in ~six months?

I've go a bunch of ideas I'd like to talk about.. But first
a laser diode (750- 900 nm?) and a PD.

George H.

*I talked with this a bit with Phil H. He was concerned
that a laser diode is not a thermal source... which very well might
be right... (I need to do the experiment.)
I tried to do this measurement (excess noise, single detector)
with a Rb discharge lamp, small iris, and PD detector.
There just wasn't enough light. (According to Bloom and Bell,
(first guys to write about Rb lamps) when run at maximum light
The intensity is such that each Rb atom within one optical
path length of the surface emits one photon per Rb lifetime.
So I'm hoping the laser diode with photons created all along
it's length will have enough.


If you plot a 2-D histogram (aka constellation plot for comms guys) of
the probability of measurement vs I and Q amplitude components of laser
light, the results are very different from thermal light.

In thermal light, I and Q are statistically independent, so you get a
2-D Gaussian peak centred around the origin in the constellation plot.

In laser light, the pumping rate constrains sqrt(I**2 + Q**2) to be
nearly constant. Thus the constellation plot is a mildly funny annulus,
essentially zero at the origin.

Goodman's "Statistical Optics" has a plot of this someplace. I'm
currently coming to you from sunny Anna Maria, Florida, which is EOI
South till the end of the month, and Amazon doesn't have a 'search
inside' for the book.

(By the way, I take full credit for the warm winter in the NE--I booked
this place back in July.)
Enjoy the warmth. It's rainy, 35F and muddy here.
(~freezing point of water and 100% humidity is my least favorite
weather.)
I've got an e-version of Goldman's book.. I'll give it a look see.
Any hints on where or what to look for?

I'm mostly confused when it comes to photon statistics.
So I and Q.. you are looking at 'noise' from the light source at one
frequency and two (orthogonal) phases?...
How hard is that to do? A picture of the set up would help
a lot with my understanding. :^)

You have to have a phase reference someplace, which is easy in RF but
much harder at optical frequencies. It's possible using a delay line
discriminator, where you interfere the beam against an old copy of
itself. The delay has to be large compared with 1/linewidth in the
simplest case. That's not super hard to do in fibre.

One could also use two lasers whose centre frequencies are offset by
more than the sum of their line widths. That way you'd measure the
convolution of the two phases, which would tend to fill in the centre of
the annular distributions. It comes out as an RF beat that you can
measure electronically.

Alternatively one could use three lasers and look at the closure phase.
(I haven't done the math on that in 20 years or more, but with three
lasers you get three unique pairs, so you get unique measurements of all
the relative frequencies and phases except for the average of them all.

I've been thinking about some similar stuff today--I really need a
wavefront measuring interferometer for sub-1mm beams. I'll start a
cross-posted thread here and in sci.optics at some point, because there
are points of interest for both groups.

Cheers

Phil Hobbs




--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[George Herold]

On Tuesday, February 4, 2020 at 1:58:28 PM UTC-5, Phil Hobbs wrote:

On 2020-02-04 12:38, George Herold wrote:
On Tuesday, February 4, 2020 at 10:59:11 AM UTC-5, Phil Hobbs wrote:
On 2020-02-04 09:58, George Herold wrote:
Hi all, So another crazy idea of a project/ physics lab. I went looking
on the web for a decent resource.. couldn't find one, so I made a little
intro here,
https://www.dropbox.com/s/91fd1gcswzxh416/hbt1.txt?dl=0
(I'm a little confused about some of the math, so hand-wavy)
One could observe HBT in two ways. Either excess noise in a single
detector (above shot noise) or correlations in the noise with
two detectors.
The idea is to use a laser diode run below threshold as the light
source*. I did this measurement ~10 years ago, and at ~10% below
threshold, I saw enough photo-current such that the wave noise
would be about 10% of the shot noise.
If I did all the numbers right!???

So that's the first thing to check.
Get a laser diode and measure photo-current at proper distance
away, and then measure BW (of diode).

If that looks OK then full speed ahead! I should be able to
get something up and running in ~six months?

I've go a bunch of ideas I'd like to talk about.. But first
a laser diode (750- 900 nm?) and a PD.

George H.

*I talked with this a bit with Phil H. He was concerned
that a laser diode is not a thermal source... which very well might
be right... (I need to do the experiment.)
I tried to do this measurement (excess noise, single detector)
with a Rb discharge lamp, small iris, and PD detector.
There just wasn't enough light. (According to Bloom and Bell,
(first guys to write about Rb lamps) when run at maximum light
The intensity is such that each Rb atom within one optical
path length of the surface emits one photon per Rb lifetime.
So I'm hoping the laser diode with photons created all along
it's length will have enough.


If you plot a 2-D histogram (aka constellation plot for comms guys) of
the probability of measurement vs I and Q amplitude components of laser
light, the results are very different from thermal light.

In thermal light, I and Q are statistically independent, so you get a
2-D Gaussian peak centred around the origin in the constellation plot.

In laser light, the pumping rate constrains sqrt(I**2 + Q**2) to be
nearly constant. Thus the constellation plot is a mildly funny annulus,
essentially zero at the origin.

Goodman's "Statistical Optics" has a plot of this someplace. I'm
currently coming to you from sunny Anna Maria, Florida, which is EOI
South till the end of the month, and Amazon doesn't have a 'search
inside' for the book.

(By the way, I take full credit for the warm winter in the NE--I booked
this place back in July.)
Enjoy the warmth. It's rainy, 35F and muddy here.
(~freezing point of water and 100% humidity is my least favorite
weather.)
I've got an e-version of Goldman's book.. I'll give it a look see.
Any hints on where or what to look for?

I'm mostly confused when it comes to photon statistics.
So I and Q.. you are looking at 'noise' from the light source at one
frequency and two (orthogonal) phases?...
How hard is that to do? A picture of the set up would help
a lot with my understanding. :^)

You have to have a phase reference someplace, which is easy in RF but
much harder at optical frequencies. It's possible using a delay line
discriminator, where you interfere the beam against an old copy of
itself. The delay has to be large compared with 1/linewidth in the
simplest case. That's not super hard to do in fibre.
OK so a semi crappy laser... nothing locked to some atomic line.

One could also use two lasers whose centre frequencies are offset by
more than the sum of their line widths. That way you'd measure the
convolution of the two phases, which would tend to fill in the centre of
the annular distributions. It comes out as an RF beat that you can
measure electronically.

Ahh OK I did this with 'my' diode laser to measure the line width
I locked one to an Rb line and let the other drift around ~100 MHz away,
beat into fast PD. And into a fast DDS. (limited record length of 'scope
set limit on measurement. :^(

Alternatively one could use three lasers and look at the closure phase.
(I haven't done the math on that in 20 years or more, but with three
lasers you get three unique pairs, so you get unique measurements of all
the relative frequencies and phases except for the average of them all.

Well with three you can beat them all against each other and find the BW of
each...the two laser measurement I did measures some average..
You could have one really good one and not know it.

I've been thinking about some similar stuff today--I really need a
wavefront measuring interferometer for sub-1mm beams. I'll start a
cross-posted thread here and in sci.optics at some point, because there
are points of interest for both groups.

Hmm I know almost nothing about wave front interferometery...
A big 'flat' piece of glass with mirror on surface.

We built an interferometer that did white light.
Beautiful colors and shapes when working...
The first one had horrible distortion in the beam-splitter.
(due to how it was held.)

George H.

Cheers

Phil Hobbs




--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[speff]

On Friday, 6 December 2019 10:19:00 UTC-5, Winfield Hill wrote:

Our publisher, Cambridge University Press, is
offering the AoE x-Chapters, at a 20% discount.
until 29 February. "use code AEX2019P at the
checkout to receive a 20% discount!"

https://view.updates.cambridge.org/?qs=e5cee29db3292f77662e391d0ad84649df61c049e5a1ea7f5725fcdc4d6b171a8c35523f08a0116ce2c476d7bd11ffc0ef97587b42f9f7e462ea6d6d7cd02b077aba63d0ae44ea83d2d46e6901d9d796

Paul and I have had our copies for over a week
now, and palettes of books are making their way
to CUP's warehouse, 9000 copies this printing.
CUP will ship well before Amazon, and others.
Get 524 big pages of good stuff, $48 plus s/h.

Also, our own x-Chapter web page is up, which
includes 11 sample sections you can download.
And I've posted drafts of other sections here.
So you can start your reading right away.

https://x.artofelectronics.net

We've already posted the first errata, so read
and act fast, get your name honored on the web!

I process all notes about typos, and our editor
fixes them for the next printing, thanks! But
only genuine errors people need to know about,
end up on the errata section. We worked hard,
and were buried in masses of detail, so I know
there are errors. They just need to be found.


--
Thanks,
- Win

Thanks, mine has come in. It's X-cellent.

Best regards,
Spehro Pefhany

 

[Phil Allison]

Phil Allison wrote:

-------------------

Hi to all my pals,


on the bench I have a US made, bass instrument amplifier (Eden) in near new condition. It uses a 600VA toroidal tranny in the PSU.

The "T5A" 20mm AC fuse installed was blown and also a similar previous fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitted.

However, repeated switch on testing shows max, peak inrush surges over 120 amps, either polarity.

But mysteriously, resistance readings at the IEC inlet are variable:

Eg:

DMM = 83 ohms either way.

Analogue meter = 25 to 35 ohms, depending on polarity.

DC bench supply = 0.5 A at 2 volts & 1A at 3V.

Any intelligent guesses ?

Bet no-one gets it right.

** Sorry for the long delay.....


My bet is safe, no-one got the answer.

Jason Betts was the closest.

The "Eden" amplifier uses a 25 amp TO3 style triac in series with the primary of the mains tranny.

The front panel on/off switch is a mini rocker so not rated to take the fierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resistor from MT2 to gate of the triac to do the heavy work.

Works like a charm and the switch never burns out.

Seen the same scheme used on a few audio amplifiers and PSUs.


...... Phil

 

[Bill Sloman]

On Friday, February 7, 2020 at 12:03:08 PM UTC+11, Phil Allison wrote:

Phil Allison wrote:

-------------------

Hi to all my pals,


on the bench I have a US made, bass instrument amplifier (Eden) in near new condition. It uses a 600VA toroidal tranny in the PSU.

The "T5A" 20mm AC fuse installed was blown and also a similar previous fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitted..

However, repeated switch on testing shows max, peak inrush surges over 120 amps, either polarity.

But mysteriously, resistance readings at the IEC inlet are variable:

Eg:

DMM = 83 ohms either way.

Analogue meter = 25 to 35 ohms, depending on polarity.

DC bench supply = 0.5 A at 2 volts & 1A at 3V.

Any intelligent guesses ?

Bet no-one gets it right.



** Sorry for the long delay.....


My bet is safe, no-one got the answer.

Jason Betts was the closest.

The "Eden" amplifier uses a 25 amp TO3 style triac in series with the primary of the mains tranny.

The front panel on/off switch is a mini rocker so not rated to take the fierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resistor from MT2 to gate of the triac to do the heavy work.

Works like a charm and the switch never burns out.

Seen the same scheme used on a few audio amplifiers and PSUs.

I got to install an AC-excited contactor on one of Cambridge Instruments to deal with the same problem.

I made a hash of it. I sized the transformer to excite the contactor on the basis of it's sustained load, and it was marginal for the load presented while the contractor was closing. There was room for the slightly bigger transformer that would deliver enough power to reliably close the contactor, so it wasn't as embarrassing as it might have been.

--
Bill Sloman, Sydney

 

[boB]

Triac in series with the transformer was what I guessed too except I
was thinking that it was being used as a light dimmer circuit for
voltage regulation.

Where was Phil all this time anyway ?

He sounds kind of like Trump in his attitude of knowing everything
about all things audio.




On Thu, 6 Feb 2020 19:05:56 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

On Friday, February 7, 2020 at 12:03:08 PM UTC+11, Phil Allison wrote:
Phil Allison wrote:

-------------------

Hi to all my pals,


on the bench I have a US made, bass instrument amplifier (Eden) in near new condition. It uses a 600VA toroidal tranny in the PSU.

The "T5A" 20mm AC fuse installed was blown and also a similar previous fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitted.

However, repeated switch on testing shows max, peak inrush surges over 120 amps, either polarity.

But mysteriously, resistance readings at the IEC inlet are variable:

Eg:

DMM = 83 ohms either way.

Analogue meter = 25 to 35 ohms, depending on polarity.

DC bench supply = 0.5 A at 2 volts & 1A at 3V.

Any intelligent guesses ?

Bet no-one gets it right.



** Sorry for the long delay.....


My bet is safe, no-one got the answer.

Jason Betts was the closest.

The "Eden" amplifier uses a 25 amp TO3 style triac in series with the primary of the mains tranny.

The front panel on/off switch is a mini rocker so not rated to take the fierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resistor from MT2 to gate of the triac to do the heavy work.

Works like a charm and the switch never burns out.

Seen the same scheme used on a few audio amplifiers and PSUs.

I got to install an AC-excited contactor on one of Cambridge Instruments to deal with the same problem.

I made a hash of it. I sized the transformer to excite the contactor on the basis of it's sustained load, and it was marginal for the load presented while the contractor was closing. There was room for the slightly bigger transformer that would deliver enough power to reliably close the contactor, so it wasn't as embarrassing as it might have been.

 

[Bill Sloman]

On Monday, February 3, 2020 at 6:21:27 AM UTC+11, Phil Hobbs wrote:

On 2020-02-02 03:28, Klaus Kragelund wrote:
My product is 20x20x20 cm

I live in Denmark and the last couple of years we have had extremely
mild winters, averaged 5.4 degrees in January, a all time record

https://www.dr.dk/nyheder/viden/klima/varmeste-januar-nogensinde-er-det-klimaforandringernes-skyld

So I need a chamber that works a room temperature

A beer fridge for the chamber, a resistive heater, and a jug of liquid
CO2 for cooling. Back when I was a real RF engineer, we had an
environmental chamber that worked like that. Round here you can get
your CO2 at a sporting goods store that sells paintball gear.

Liquid CO2 would be a first. It might even get you a Nobel Prize.

Phil probably means liquid nitrogen. Pouring that into a jug might create enough thermal stress to break the jug. A thermos works better, but you may need to drop a resistor into the liquid and boil off enough liquid nitrogen gas (at -195.8 C or 77.2 K) to counter-act the heat flow in from the outside world.

Getting liquid nitrogen is like getting milk delivered, but you need a big enough container to store about a week's worth, well insulated enough to let it last a week. Foamed polystyrene may not hack it.

--
Bill Sloman, Sydney

 

[Phil Allison]

Bill Sloman wrote:

--------------------

Hi to all my pals,


on the bench I have a US made, bass instrument amplifier (Eden) in near new condition. It uses a 600VA toroidal tranny in the PSU.

The "T5A" 20mm AC fuse installed was blown and also a similar previous fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitted.

However, repeated switch on testing shows max, peak inrush surges over 120 amps, either polarity.

But mysteriously, resistance readings at the IEC inlet are variable:

Eg:

DMM = 83 ohms either way.

Analogue meter = 25 to 35 ohms, depending on polarity.

DC bench supply = 0.5 A at 2 volts & 1A at 3V.

Any intelligent guesses ?

Bet no-one gets it right.



** Sorry for the long delay.....


My bet is safe, no-one got the answer.

Jason Betts was the closest.

The "Eden" amplifier uses a 25 amp TO3 style triac in series with the primary of the mains tranny.

The front panel on/off switch is a mini rocker so not rated to take the fierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resistor from MT2 to gate of the triac to do the heavy work.

Works like a charm and the switch never burns out.

Seen the same scheme used on a few audio amplifiers and PSUs.


I got to install an AC-excited contactor on one of Cambridge Instruments to deal with the same problem.

I made a hash of it. I sized the transformer to excite the contactor on the basis of it's sustained load, and it was marginal for the load presented while the contractor was closing. There was room for the slightly bigger transformer that would deliver enough power to reliably close the contactor, so it wasn't as embarrassing as it might have been.

** Confucious say:

" Man thinking how to avoid embarrassment spend more effort than when making same embarrassment."


..... Phil

 

[Bill Sloman]

On Friday, February 7, 2020 at 3:19:23 PM UTC+11, boB wrote:

Triac in series with the transformer was what I guessed too except I
was thinking that it was being used as a light dimmer circuit for
voltage regulation.

Where was Phil all this time anyway ?

He sounds kind of like Trump in his attitude of knowing everything
about all things audio.

Don't top post.

Phil doesn't sound in the least like Trump, not least because he comes pretty close to actually knowing everything about a lot of audio stuff - he doesn't say much about digital audio, so "all things audio" isn't entirely fair.

Trump's problem is that he hasn't got the attention span to sit through briefings that are long enough to tell him as much as he needs to know, which - combined with excessive self-belief - encourages him to get on with doing something, when that something is frequently ill-advised (because he wouldn't sit still long enough to absorb proper advice).

--
Bill Sloman, Sydney

 

[Rick C]

On Sunday, February 2, 2020 at 4:03:16 PM UTC-5, DecadentLinux...@decadence..org wrote:

Klaus Kragelund <klauskvik@hotmail.com> wrote in
news:484e78ef-6290-493c-bbd0-7c6bfe76e4a0@googlegroups.com:

On Sunday, February 2, 2020 at 3:37:03 PM UTC+1,
upsid...@downunder.com wrote:
On Sat, 1 Feb 2020 09:03:47 -0800 (PST), Klaus Kragelund
klauskvik@hotmail.com> wrote:

Hi

I am working on something for my own business

So need to do testing at below 0 degrees C

What would be a cheapskate way to do it?

Just a household freezer?

Product is just 20x20x20

There are some issues with electronics in cold temperatures.

One problem with any processor based (or sequentially logic)
system is starting the clock oscillator at extreme low
temperatures. This can be quite unreliable. Once the clock is
running, the electronics will generate some internal heat
warming the components in the box to higher temperatures. Thus,
even i some components are initially out of specs it will be
within specs after a while.

When doing cold testing, let the device cool to the lowest
temperature obtainable with equipment power turned off. Once the
lowest temperature has been achieved, turn equipment power on and
verify that the clock starts. Once running, make sure the box
outside temperature remains in your case at -20 C despite the 5 W
heating,

We have big, super expensive chambers at work, where we always do
that LOL and UOL (Lower Operating Limit and Upper Operating
Limit), which has the purpose you mention to find when it really
fails. We would normally have the LOL at -50 and UOL at 150. But
for my own business if I can do a minus 20 test and 150 then I
feel pretty safe

When doing indoor cool chamber tests, the initial air contains
some absolute humidity. While the chamber cools down, the
relative humidity RH increases, finally reaching 100 %, after
which condensation or frost will accumulate. Do not put the
equipment directly on the bottom of the chamber, since there
might be some condensation water on the bottom. The condensation
or frost may cause problems with uncoated PCBs.


Yes. Also, don't open the chamber when at -40, tried that, won't
do it again (heavy condensation)

Cheers

Klaus


Place the UUT in a Fluorinert bath.

I wanted to do an entire motherbaord that way and go down below and
clock up above what the OC boys do. Some of the videos are amusing
watching some dude pouring LN2 over a CPU.

My solution <sic> would work, and for long term too, not "I OC'd my
PC to 10GHz" (for 1 minute long enough to run the benchmark). It is
funny watching them make claims. My PC in a fish tank method would
work down to -70°C with FC-72 Fluorinert. And run... all day.

Maybe, maybe not. I recall an outfit that was working on cooling military electronics. They used something like Fluorinert but instead of immersion which actually provides thermal barriers from limited conductivity of the fluid, they sprayed it on using patented nozzles to obtain optimum droplet size and used the heat of vaporization to cool. While that would not cool to -70°C, it removes more heat than immersion would until your device heated up to at least 10°C but actually higher due to the thermal conduction issues of the liquid.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:45c6c4d5-81e3-4756-bd71-cff8fd38bded@googlegroups.com:

On Sunday, February 2, 2020 at 4:03:16 PM UTC-5,
DecadentLinux...@decadence.org wrote:
Klaus Kragelund <klauskvik@hotmail.com> wrote in
news:484e78ef-6290-493c-bbd0-7c6bfe76e4a0@googlegroups.com:

On Sunday, February 2, 2020 at 3:37:03 PM UTC+1,
upsid...@downunder.com wrote:
On Sat, 1 Feb 2020 09:03:47 -0800 (PST), Klaus Kragelund
klauskvik@hotmail.com> wrote:

Hi

I am working on something for my own business

So need to do testing at below 0 degrees C

What would be a cheapskate way to do it?

Just a household freezer?

Product is just 20x20x20

There are some issues with electronics in cold temperatures.

One problem with any processor based (or sequentially logic)
system is starting the clock oscillator at extreme low
temperatures. This can be quite unreliable. Once the clock is
running, the electronics will generate some internal heat
warming the components in the box to higher temperatures.
Thus, even i some components are initially out of specs it
will be within specs after a while.

When doing cold testing, let the device cool to the lowest
temperature obtainable with equipment power turned off. Once
the lowest temperature has been achieved, turn equipment power
on and verify that the clock starts. Once running, make sure
the box outside temperature remains in your case at -20 C
despite the 5 W heating,

We have big, super expensive chambers at work, where we always
do that LOL and UOL (Lower Operating Limit and Upper Operating
Limit), which has the purpose you mention to find when it
really fails. We would normally have the LOL at -50 and UOL at
150. But for my own business if I can do a minus 20 test and
150 then I feel pretty safe

When doing indoor cool chamber tests, the initial air contains
some absolute humidity. While the chamber cools down, the
relative humidity RH increases, finally reaching 100 %, after
which condensation or frost will accumulate. Do not put the
equipment directly on the bottom of the chamber, since there
might be some condensation water on the bottom. The
condensation or frost may cause problems with uncoated PCBs.


Yes. Also, don't open the chamber when at -40, tried that,
won't do it again (heavy condensation)

Cheers

Klaus


Place the UUT in a Fluorinert bath.

I wanted to do an entire motherbaord that way and go down below
and
clock up above what the OC boys do. Some of the videos are
amusing watching some dude pouring LN2 over a CPU.

My solution <sic> would work, and for long term too, not "I
OC'd my
PC to 10GHz" (for 1 minute long enough to run the benchmark). It
is funny watching them make claims. My PC in a fish tank method
would work down to -70°C with FC-72 Fluorinert. And run... all
day.

Maybe, maybe not. I recall an outfit that was working on cooling
military electronics. They used something like Fluorinert but
instead of immersion which actually provides thermal barriers from
limited conductivity of the fluid, they sprayed it on using
patented nozzles to obtain optimum droplet size and used the heat
of vaporization to cool. While that would not cool to -70°C, it
removes more heat than immersion would until your device heated up
to at least 10°C but actually higher due to the thermal
conduction issues of the liquid.

Fluorinert does not vaporize and the immersion unit would have the
fluorinert always flowing over the parts. And oh fluorinert has very
good thermal conductivity. It would work well in seal, conduction
cooled designs as well, where no movement happens or is needed. They
work far better than a friggin thermal pad or even a directly
attached air flow heat sink.

 

[Bill Sloman]

On Friday, February 7, 2020 at 5:49:07 PM UTC+11, DecadentLinux...@decadence.org wrote:

Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:45c6c4d5-81e3-4756-bd71-cff8fd38bded@googlegroups.com:

On Sunday, February 2, 2020 at 4:03:16 PM UTC-5,
DecadentLinux...@decadence.org wrote:
Klaus Kragelund <klauskvik@hotmail.com> wrote in
news:484e78ef-6290-493c-bbd0-7c6bfe76e4a0@googlegroups.com:

On Sunday, February 2, 2020 at 3:37:03 PM UTC+1,
upsid...@downunder.com wrote:
On Sat, 1 Feb 2020 09:03:47 -0800 (PST), Klaus Kragelund
klauskvik@hotmail.com> wrote:

Hi

I am working on something for my own business

So need to do testing at below 0 degrees C

What would be a cheapskate way to do it?

Just a household freezer?

Product is just 20x20x20

There are some issues with electronics in cold temperatures.

One problem with any processor based (or sequentially logic)
system is starting the clock oscillator at extreme low
temperatures. This can be quite unreliable. Once the clock is
running, the electronics will generate some internal heat
warming the components in the box to higher temperatures.
Thus, even i some components are initially out of specs it
will be within specs after a while.

When doing cold testing, let the device cool to the lowest
temperature obtainable with equipment power turned off. Once
the lowest temperature has been achieved, turn equipment power
on and verify that the clock starts. Once running, make sure
the box outside temperature remains in your case at -20 C
despite the 5 W heating,

We have big, super expensive chambers at work, where we always
do that LOL and UOL (Lower Operating Limit and Upper Operating
Limit), which has the purpose you mention to find when it
really fails. We would normally have the LOL at -50 and UOL at
150. But for my own business if I can do a minus 20 test and
150 then I feel pretty safe

When doing indoor cool chamber tests, the initial air contains
some absolute humidity. While the chamber cools down, the
relative humidity RH increases, finally reaching 100 %, after
which condensation or frost will accumulate. Do not put the
equipment directly on the bottom of the chamber, since there
might be some condensation water on the bottom. The
condensation or frost may cause problems with uncoated PCBs.


Yes. Also, don't open the chamber when at -40, tried that,
won't do it again (heavy condensation)

Place the UUT in a Fluorinert bath.

I wanted to do an entire motherbaord that way and go down below and clock up above what the OC boys do. Some of the videos are
amusing watching some dude pouring LN2 over a CPU.

My solution <sic> would work, and for long term too, not "I OC'd my PC to 10GHz" (for 1 minute long enough to run the benchmark). It is funny watching them make claims. My PC in a fish tank method would work down to -70°C with FC-72 Fluorinert. And run... all day.

Maybe, maybe not. I recall an outfit that was working on cooling
military electronics. They used something like Fluorinert but
instead of immersion which actually provides thermal barriers from
limited conductivity of the fluid, they sprayed it on using
patented nozzles to obtain optimum droplet size and used the heat
of vaporization to cool. While that would not cool to -70°C, it
removes more heat than immersion would until your device heated up
to at least 10°C but actually higher due to the thermal
conduction issues of the liquid.


Fluorinert does not vaporize

Of course it vaporises if you get it hot enough.

https://en.wikipedia.org/wiki/Fluorinert

and the immersion unit would have the
fluorinert always flowing over the parts. And oh fluorinert has very
good thermal conductivity. It would work well in sealed, conduction
cooled designs as well, where no movement happens or is needed.

If they didn't get too hot. "No movement" is unlikely. Convection in a liquid can shift quite a lot of heat - if nowhere near as much as evaporation and condensation.

They work far better than a friggin thermal pad or even a directly
attached air flow heat sink.

They'd work even better in a heat-pipe set-up, but water is mostly good enough there.

--
Bill Sloman, Sydney