Hi

Grab your DVM and take a look at the voltage on the input caps on one of those
supplies as compared to the output voltage. With light loads (which is how most
use them …) the voltage ratio is pretty high. As a result, the efficiency is not as
good as it could be.

The Acopian versions that come fully enclosed are no more efficient, but are nicely
protected from “stuff". Like the rest, they can be found on eBay for not a lot of money ….

Bob

Just got this in the mail I am sure they have related items.           
We use with very good results Mean Well SD DC/DC products, for my Rb 8607 project I plan on using Traco Power
https://www.maximintegrated.com/en/design/reference-design-center/ref-circuits/7055.html?utm_source=Eloqua&utm_medium=email&utm_content=REFDES1234&utm_campaign=FY20_Q3_2020_FEB_ALL-BU_AMER_EE-Mail_EN
Bert Kehren

In a message dated 2/8/2020 11:45:09 AM Eastern Standard Time, kd4pbj@gmail.com writes:

Hi Taka,

How about using the open frame linear supplies like the ones from Power One or Lambda?
I usually pick these up when I find them, recap if needed and they're a cheap and easy way to get a supply.

Chris
KD4PBJ

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Hi Bert,

Make sure to measure the noise on the Traco (on both input and output)
We had some issue with noise from a couple of Traco models at work. We
changed to Mean Well, and much less noise....

Br,
Askild

On Sat, Feb 8, 2020 at 8:10 PM ew via time-nuts time-nuts@lists.febo.com
wrote:

Thank you for your warning. Have not bought Traco but was considered after Poul-Henning recommendation. Will stay with Mean Well have plenty good experience,  a couple % more efficiency was tempting no more         
Bert Kehren

In a message dated 2/8/2020 4:43:02 PM Eastern Standard Time, megafluffy@gmail.com writes:

Hi Bert,

Make sure to measure the noise on the Traco (on both input and output)
We had some issue with noise from a couple of Traco models at work. We
changed to Mean Well, and much less noise....

Br,
Askild

On Sat, Feb 8, 2020 at 8:10 PM ew via time-nuts time-nuts@lists.febo.com
wrote:

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and follow the instructions there.

I just put pieces together for my project.  It's in a 2U rack case.  AND REALIZED RACK FLANGE IS ON BACK PANEL!  Geez...  Now, I have to re-drill some holes and turn it around.  This particular case has integrated flange.  It's part of the side panel - and power supply is mounted there.  I can't believe I did that.
Bert,
I saw some advertisement on Amazon where other companies are starting to use MW logo and Mean Well name on their product.  When I looked at it, it was clear the unit itself isn't MeanWell.  I'm thinking before too long, there will be counterfeit one floating around....  I guess the name and reputation is starting to develop and unethical companies are piggy backing on their name.

(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG

On Saturday, February 8, 2020, 5:59:12 PM EST, ew via time-nuts <time-nuts@lists.febo.com> wrote:  

Thank you for your warning. Have not bought Traco but was considered after Poul-Henning recommendation. Will stay with Mean Well have plenty good experience,  a couple % more efficiency was tempting no more         
Bert Kehren

In a message dated 2/8/2020 4:43:02 PM Eastern Standard Time, megafluffy@gmail.com writes:

Hi Bert,

Make sure to measure the noise on the Traco (on both input and output)
We had some issue with noise from a couple of Traco models at work. We
changed to Mean Well, and much less noise....

Br,
Askild

On Sat, Feb 8, 2020 at 8:10 PM ew via time-nuts time-nuts@lists.febo.com
wrote:

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Chris wrote:

I have had very good results with Deltron open-frame linear supplies.
They have selectable mains voltage and low output noise (1mVrms/5mVp-p).
I have used many (i.e., hundreds) of the Model W303E triple-output
supply.  These have one, 5v/8A section and two sections, each selectable
between 5v/12v/15v at 0.7A/1.7A/1.5A.  [NOTE there is an overall 55W
output limit, so they will not do all of that at once.]  Each section
can be adjusted +/- 5%.  These show up regularly on ebay.

As for switchers, I have been satisfied with the performance of
Integrated Power Designs (IPD) products.  [IPD is a different company
than Power Designs, who made some of the best lab and bench power
supplies of the 1960s through 1990s.]  One in particular may be of
interest to time nuts: the Model SRW-65-4006.  This is a four-output
supply (5v/5A, 24v/1A, and +/-15v/2A) [NOTE again, there is a 65W
overall limit, so it won't do all of that at once].  It is available
open-frame or with a chassis and cover.  For installation close to other
circuitry, and particularly inside a piece of equipment, I strongly
recommend the model with both chassis and cover (options CH and CO).
Check ebay and look at distributors.

Assume you will need to post-filter the switcher output, either with L/C
filters or low noise linear regulators.  Note that I did not say "LDOs".
I don't know why, but everyone seems to be stuck on LDOs these days.
Active regulators (including LDOs) always perform better with more
headroom (up to 4v or so).  The only excuse for designing LDO is if you
have a gun to your head from a power budget you can't otherwise control.
[Here, "LDO" is mostly a matter of how you use the part, not of its
claimed capabilities -- "LDO" regulators work much better with at least
4v of headroom.]

Best regards,

Charles

I spent last two days boxing  up LPRO-101 into a 2U rack case.  It has Rb, dist amp, interface for LED, and EFC knob on front.  While doing so, I gave power supply concern I have been discussing careful thought.  I believe I came to something that is workable and fits my needs. 

I started with 24V linear power supply (open frame type).  This is the only power supply in the box.  From there, it branches to Rb, a small dist amp, and a simple interface circuit.  Dist amp is 12V rated and interface is 5V.  I modified the dist amp by including a 3 terminal regulator.  Now, it's a 24V device.  I crated a 5V source right at Rb's interface board to be used as EFC power.  This is the only purpose of this branch.  I also created a separate 5V for the simple interface circuit. The reason for two 5V supply is that I didn't want to mix the source for EFC and digital circuit together.

Pretty quickly, I found out going from 24V to 5V incurs huge loss resulting in heat and death of 3 terminal regulator for that branch.  EFC circuit was fine but digital interface board killed the regulator. Put a heat sink on it and issue is resolved.  A bit surprising but it shouldn't be....  The circuit only uses 25mA or so but voltage drop is huge.
Basically, I'm doing the same thing S100 bus computers did.  I will have to consider use of small smp board for large voltage drops.  I didn't this time, as its noise profile is not known to me.  Can't really go wrong with linear regulators.  My only remaining concern is if regulator fails short, then what happens??  It will kill the particular device, which I'm fine with, but what else?  Perhaps simple fuse is in order for every branch. 

This method is a lot simpler than hap-haphazardly creating multiple voltage at power supply and routing all over the place.  It became impossible to trace ground loops.  Above method makes it really easy as, as far as power supply is concerned, everything is a 24V device.
Thanks everyone for discussions.  I learned a lot in this process.

(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG

On Saturday, February 8, 2020, 9:52:02 PM EST, Charles Steinmetz <csteinmetz@yandex.com> wrote:  

Chris wrote:

I have had very good results with Deltron open-frame linear supplies.
They have selectable mains voltage and low output noise (1mVrms/5mVp-p).
  I have used many (i.e., hundreds) of the Model W303E triple-output
supply.  These have one, 5v/8A section and two sections, each selectable
between 5v/12v/15v at 0.7A/1.7A/1.5A.  [NOTE there is an overall 55W
output limit, so they will not do all of that at once.]  Each section
can be adjusted +/- 5%.  These show up regularly on ebay.

As for switchers, I have been satisfied with the performance of
Integrated Power Designs (IPD) products.  [IPD is a different company
than Power Designs, who made some of the best lab and bench power
supplies of the 1960s through 1990s.]  One in particular may be of
interest to time nuts: the Model SRW-65-4006.  This is a four-output
supply (5v/5A, 24v/1A, and +/-15v/2A) [NOTE again, there is a 65W
overall limit, so it won't do all of that at once].  It is available
open-frame or with a chassis and cover.  For installation close to other
circuitry, and particularly inside a piece of equipment, I strongly
recommend the model with both chassis and cover (options CH and CO).
Check ebay and look at distributors.

Assume you will need to post-filter the switcher output, either with L/C
filters or low noise linear regulators.  Note that I did not say "LDOs".
  I don't know why, but everyone seems to be stuck on LDOs these days.
Active regulators (including LDOs) always perform better with more
headroom (up to 4v or so).  The only excuse for designing LDO is if you
have a gun to your head from a power budget you can't otherwise control.
  [Here, "LDO" is mostly a matter of how you use the part, not of its
claimed capabilities -- "LDO" regulators work much better with at least
4v of headroom.]

Best regards,

Charles

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Taka Kamiya wrote:

Good idea to use two, 5 V supplies in this situation.

The EFC circuit presumably draws no more than 0.5 mA, so regulator power
dissipation is probably at most 19 V x 0.5 mA, or <10 mW.  As you found,
no problem.

At ~ 25 mA, the interface board dissipates ~ 19 V x 25 mA, or ~ 500 mW.
As you found, nothing a moderate heatsink can't handle.  But you don't
have to dissipate all 500 mW in the regulator.  For example, you could
feed the 5 V regulator from the 24 V supply through a 400 ohm, 1 W
resistor (putting a capacitor of, say, 470 uF to ground at the input of
the 5 V reg).  This would share the ~500 mW dissipation equally between
the 5 V regulator and the resistor.  (A 10v, 1 W  zener diode would also
work.)

Another option would be to use two, mains-powered linear power supplies
-- one 24v supply, and one 12v supply.  Then sub-regulate the two 5v
supplies from the 12v supply rather than from 24v.

A fuse by itself will not necessarily open in this situation.  If you
are worried about failing short, use a simple zener diode crowbar with
the protective fuse.  Use a shunt zener with a breakdown voltage about
2v greater than the regulated power supply voltage across the load, fed
through the protective fuse.  The fuse should be rated at about 200% of
the load current.  The zener must be sufficiently robust to withstand
the fault current until the fuse opens.

With a zener rated 2v greater than the operating voltage, there is a
good chance the downstream load will survive without damage.

Best regards,

Charles

Yes, I did consider use of a second linear supply for 12V.  But decided against it.  This particular project was to use ONE 24V supply only.  This is because of my previous project.  Also the issue with another 12V linear is that these open frame supplies are awfully inefficient.  They generate enormous amount of heat for little current.  Since this is a rubidium box, heat management was important.

On previous project, I used 24V linear supply, and 12V switcher supply.  AND 5V DC/DC off 24V, 5V 3 terminal off 12v, and 3.3V internal to one device.  Each was routed all over the place.  The end result was a good working system.  But ground situation became very complicated.  I was very concerned because EFC can easily be affected.

This is still a work in progress.  There is already a plan for 3rd iteration with GPDSO, and 4th iteration with OCXO.  I'd expect similar problems.  I'm still debating a good design as OCXO requires +/-5V supply that has to be very clean and stable. 

At one point, I plan to remake the first project.  Besides the fact it works, I didn't practice good engineering process.  Lack of foresight and slapping on STUFF as needed led to this awful configuration.  There got to be a much better way, and I got to get there for my own satisfaction.

(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG

On Wednesday, February 12, 2020, 9:49:42 PM EST, Charles Steinmetz <csteinmetz@yandex.com> wrote:  

Taka Kamiya wrote:

Good idea to use two, 5 V supplies in this situation.

The EFC circuit presumably draws no more than 0.5 mA, so regulator power
dissipation is probably at most 19 V x 0.5 mA, or <10 mW.  As you found,
no problem.

At ~ 25 mA, the interface board dissipates ~ 19 V x 25 mA, or ~ 500 mW.
  As you found, nothing a moderate heatsink can't handle.  But you don't
have to dissipate all 500 mW in the regulator.  For example, you could
feed the 5 V regulator from the 24 V supply through a 400 ohm, 1 W
resistor (putting a capacitor of, say, 470 uF to ground at the input of
the 5 V reg).  This would share the ~500 mW dissipation equally between
the 5 V regulator and the resistor.  (A 10v, 1 W  zener diode would also
work.)

Another option would be to use two, mains-powered linear power supplies
-- one 24v supply, and one 12v supply.  Then sub-regulate the two 5v
supplies from the 12v supply rather than from 24v.

A fuse by itself will not necessarily open in this situation.  If you
are worried about failing short, use a simple zener diode crowbar with
the protective fuse.  Use a shunt zener with a breakdown voltage about
2v greater than the regulated power supply voltage across the load, fed
through the protective fuse.  The fuse should be rated at about 200% of
the load current.  The zener must be sufficiently robust to withstand
the fault current until the fuse opens.

With a zener rated 2v greater than the operating voltage, there is a
good chance the downstream load will survive without damage.

Best regards,

Charles

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Hi

Unless there is something wrong with the linear supply, it will produce heat
proportional to the output load. They all have very low “parasitic” current in the
control circuits.

A unit with a damaged transformer or bad caps can indeed heat up with no
load. In that case, it needs to be repaired.

Bob