Suppose I have a bunch of PC boards in a chassis, vertical and
parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
them might be programmable ac/dc load modules.

Some of you guys work with cooling CPUs and such. If I had, say, a 3"
x 4" heat sink, and could space one or more small fans above each, how
much power might I be able to dump? The host rackmount enclosure will
have a couple of overall fans too.

The idea is roughly

https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0

https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0

We could set up a breadboard test next week, but I'd like a ballpark
now.

Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
hot, hotter than a CPU would like.

Maybe we could use several mosfets and a few commercial CPU cooler
things.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Saturday, June 5, 2021 at 10:29:45 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> Suppose I have a bunch of PC boards in a chassis, vertical and
> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> them might be programmable ac/dc load modules.
>
> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> x 4" heat sink, and could space one or more small fans above each, how
> much power might I be able to dump? The host rackmount enclosure will
> have a couple of overall fans too.
>
> The idea is roughly
>
> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>
> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>
> We could set up a breadboard test next week, but I'd like a ballpark
> now.
>
> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> hot, hotter than a CPU would like.

Do you pack your stuffs tighter than them? Each of these box is around 1000W.

https://www.bbc.com/news/uk-england-birmingham-57280115

On Sat, 05 Jun 2021 10:29:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

>Suppose I have a bunch of PC boards in a chassis, vertical and
>parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>them might be programmable ac/dc load modules.
>
>Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>x 4" heat sink, and could space one or more small fans above each, how
>much power might I be able to dump? The host rackmount enclosure will
>have a couple of overall fans too.
>
>The idea is roughly
>
>https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>
>https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>
>We could set up a breadboard test next week, but I'd like a ballpark
>now.
>
>Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>hot, hotter than a CPU would like.
>
>Maybe we could use several mosfets and a few commercial CPU cooler
>things.

These boards shouldn't be expected to move their own air - they should
just provide low backpressure and suitable fins.

If your stuff is SMD, you could have fins one side, electronics the
other.

Then you just use the catalog Rth for your fin shape and air volume.

CPU coolers aren't going to limbo under 1.75in, and all they do is
scrub.

RL

On Saturday, June 5, 2021 at 10:29:45 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> Suppose I have a bunch of PC boards in a chassis, vertical and
> parallel, about 3" x 12" each, maybe 1.25 inch centers.
>... If I had, say, a 3"
> x 4" heat sink, and could space one or more small fans above each, how
> much power might I be able to dump? The host rackmount enclosure will
> have a couple of overall fans too.

A heatsink ON a PC board is less than useful, because the PC board doesn't
shed heat very well; if you can arrange your cards to butt up against a REAL heatsink
surface (obviously, opposite the grab-here-to-extract edge) then a screw or two will connect
the hot parts to a chassis-mount sink.

Alternately, of course, you can move a few hot parts off the PC board entirely. This
is as old a solution as the preamp/poweramp two-box stereo.

There's good reason to use enclosure fans AND a ducted airflow to ventilate the heatsink bits,
but that requires you to guide that air, NOT let the host enclosure make the important decisions.
Take a look at server computers' interiors, the airflow is a key to those rackmount enclosures,
and not random 'use more fans and stir the air' bodgework.

Note here, there's a bank of seven small fans to make air go through the heatsinks
<https://i2.wp.com/9to5mac.com/wp-content/uploads/sites/6/2020/03/Xserve.png>

On Sat, 5 Jun 2021 11:20:48 -0700 (PDT), Ed Lee
<edward.ming.lee@gmail.com> wrote:

>On Saturday, June 5, 2021 at 10:29:45 AM UTC-7, jla...@highlandsniptechnology.com wrote:
>> Suppose I have a bunch of PC boards in a chassis, vertical and
>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>> them might be programmable ac/dc load modules.
>>
>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>> x 4" heat sink, and could space one or more small fans above each, how
>> much power might I be able to dump? The host rackmount enclosure will
>> have a couple of overall fans too.
>>
>> The idea is roughly
>>
>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>
>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>
>> We could set up a breadboard test next week, but I'd like a ballpark
>> now.
>>
>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>> hot, hotter than a CPU would like.
>
>Do you pack your stuffs tighter than them? Each of these box is around 1000W.
>
>https://www.bbc.com/news/uk-england-birmingham-57280115

Rough estimate on that box is about 4 watts per cubic inch.

I'll have maybe 30 cubic inches available per module.

I worked with an electrical contractor in NY City. He found adjacent
propeties where people drilled through walls to steal power from their
neighbors, occasionally in both directions.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sat, 05 Jun 2021 14:45:44 -0400, legg <legg@nospam.magma.ca> wrote:

>On Sat, 05 Jun 2021 10:29:34 -0700, jlarkin@highlandsniptechnology.com
>wrote:
>
>>Suppose I have a bunch of PC boards in a chassis, vertical and
>>parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>>them might be programmable ac/dc load modules.
>>
>>Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>>x 4" heat sink, and could space one or more small fans above each, how
>>much power might I be able to dump? The host rackmount enclosure will
>>have a couple of overall fans too.
>>
>>The idea is roughly
>>
>>https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>
>>https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>
>>We could set up a breadboard test next week, but I'd like a ballpark
>>now.
>>
>>Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>>hot, hotter than a CPU would like.
>>
>>Maybe we could use several mosfets and a few commercial CPU cooler
>>things.
>
>These boards shouldn't be expected to move their own air - they should
>just provide low backpressure and suitable fins.

Most boards will be happy with the overall box air flow. But the
higher the power rating of a dummy load board, the more sellable it
is. So more fans might be worth it.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

jlarkin@highlandsniptechnology.com wrote:
> Suppose I have a bunch of PC boards in a chassis, vertical and
> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> them might be programmable ac/dc load modules.
>
> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> x 4" heat sink, and could space one or more small fans above each, how
> much power might I be able to dump? The host rackmount enclosure will
> have a couple of overall fans too.
>
> The idea is roughly
>
> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>
> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>
> We could set up a breadboard test next week, but I'd like a ballpark
> now.
>
> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> hot, hotter than a CPU would like.
>
> Maybe we could use several mosfets and a few commercial CPU cooler
> things.

Are you trying to cool parts or just make an oven? What's the actual
airflow though the enclosure?

On Sat, 5 Jun 2021 20:41:41 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

>jlarkin@highlandsniptechnology.com wrote:
>> Suppose I have a bunch of PC boards in a chassis, vertical and
>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>> them might be programmable ac/dc load modules.
>>
>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>> x 4" heat sink, and could space one or more small fans above each, how
>> much power might I be able to dump? The host rackmount enclosure will
>> have a couple of overall fans too.
>>
>> The idea is roughly
>>
>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>
>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>
>> We could set up a breadboard test next week, but I'd like a ballpark
>> now.
>>
>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>> hot, hotter than a CPU would like.
>>
>> Maybe we could use several mosfets and a few commercial CPU cooler
>> things.
>
>Are you trying to cool parts or just make an oven?

Are you trying to be funny? I said it was a programmable dummy load
module. They tend to dissipate power.

>What's the actual
>airflow though the enclosure?

The rackmount box will have two fans, 60 cfm each, and that has to
cool the kilowatt power supply, the control board, and up to 10 power
modules. The switcher modules should be fine, but the load modules
need all the cooling they can get. Cooler = better specs = more sales.

Some sort of ducting would help some, but that's a hassle to
fabricate. A couple of local fans might work better.

An L-bracket down to the box bottom is a possibility too. We'd have to
experiment to see how well that might work. It would make module
installation a bit harder.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

søndag den 6. juni 2021 kl. 00.08.39 UTC+2 skrev jla...@highlandsniptechnology.com:
> On Sat, 5 Jun 2021 20:41:41 +0000 (UTC), Cydrome Leader
> <pres...@MUNGEpanix.com> wrote:
>
> >jla...@highlandsniptechnology.com wrote:
> >> Suppose I have a bunch of PC boards in a chassis, vertical and
> >> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> >> them might be programmable ac/dc load modules.
> >>
> >> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> >> x 4" heat sink, and could space one or more small fans above each, how
> >> much power might I be able to dump? The host rackmount enclosure will
> >> have a couple of overall fans too.
> >>
> >> The idea is roughly
> >>
> >> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
> >>
> >> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
> >>
> >> We could set up a breadboard test next week, but I'd like a ballpark
> >> now.
> >>
> >> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> >> hot, hotter than a CPU would like.
> >>
> >> Maybe we could use several mosfets and a few commercial CPU cooler
> >> things.
> >
> >Are you trying to cool parts or just make an oven?
> Are you trying to be funny? I said it was a programmable dummy load
> module. They tend to dissipate power.
> >What's the actual
> >airflow though the enclosure?
> The rackmount box will have two fans, 60 cfm each, and that has to
> cool the kilowatt power supply, the control board, and up to 10 power
> modules. The switcher modules should be fine, but the load modules
> need all the cooling they can get. Cooler = better specs = more sales..
>
> Some sort of ducting would help some, but that's a hassle to
> fabricate. A couple of local fans might work better.
>
> An L-bracket down to the box bottom is a possibility too. We'd have to
> experiment to see how well that might work. It would make module
> installation a bit harder.

https://www.aspsys.com/servers/catalog/R1304WF0YS_angle_detailed.jpg

:)

On Sat, 05 Jun 2021 12:31:01 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Sat, 05 Jun 2021 14:45:44 -0400, legg <legg@nospam.magma.ca> wrote:
>
>>On Sat, 05 Jun 2021 10:29:34 -0700, jlarkin@highlandsniptechnology.com
>>wrote:
>>
>>>Suppose I have a bunch of PC boards in a chassis, vertical and
>>>parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>>>them might be programmable ac/dc load modules.
>>>
>>>Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>>>x 4" heat sink, and could space one or more small fans above each, how
>>>much power might I be able to dump? The host rackmount enclosure will
>>>have a couple of overall fans too.
>>>
>>>The idea is roughly
>>>
>>>https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>>
>>>https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>>
>>>We could set up a breadboard test next week, but I'd like a ballpark
>>>now.
>>>
>>>Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>>>hot, hotter than a CPU would like.
>>>
>>>Maybe we could use several mosfets and a few commercial CPU cooler
>>>things.
>>
>>These boards shouldn't be expected to move their own air - they should
>>just provide low backpressure and suitable fins.
>
>Most boards will be happy with the overall box air flow. But the
>higher the power rating of a dummy load board, the more sellable it
>is. So more fans might be worth it.

Just use non-smd real estate and air volume for more heatsink fins
in the board plane.

Gives the system fans something to work with, not a squirrel's nest.

RL

jlarkin@highlandsniptechnology.com wrote:
> On Sat, 5 Jun 2021 20:41:41 +0000 (UTC), Cydrome Leader
> <presence@MUNGEpanix.com> wrote:
>
>>jlarkin@highlandsniptechnology.com wrote:
>>> Suppose I have a bunch of PC boards in a chassis, vertical and
>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>>> them might be programmable ac/dc load modules.
>>>
>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>>> x 4" heat sink, and could space one or more small fans above each, how
>>> much power might I be able to dump? The host rackmount enclosure will
>>> have a couple of overall fans too.
>>>
>>> The idea is roughly
>>>
>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>>
>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>>
>>> We could set up a breadboard test next week, but I'd like a ballpark
>>> now.
>>>
>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>>> hot, hotter than a CPU would like.
>>>
>>> Maybe we could use several mosfets and a few commercial CPU cooler
>>> things.
>>
>>Are you trying to cool parts or just make an oven?
>
> Are you trying to be funny? I said it was a programmable dummy load
> module. They tend to dissipate power.

No, I actually work equipment that dissipates lots of heat and requires
cooling.
>>What's the actual
>>airflow though the enclosure?
>
> The rackmount box will have two fans, 60 cfm each, and that has to
> cool the kilowatt power supply, the control board, and up to 10 power
> modules. The switcher modules should be fine, but the load modules
> need all the cooling they can get. Cooler = better specs = more sales.

60CFM with no pressure, or measured?
> Some sort of ducting would help some, but that's a hassle to
> fabricate. A couple of local fans might work better.

So you want an oven, not a cooling system. What I'm getting at is cooling
requires removal of heat, and not blowing it around some box with randomly
placed corny fans.

> An L-bracket down to the box bottom is a possibility too. We'd have to
> experiment to see how well that might work. It would make module
> installation a bit harder.

If you just want to move heat a short distance, say to the back of a
chassis, consider heat pipes. Noren is a good supplier. They also make a
box that removes heat from enclosures without requiring an air inlet and
outlet in the area being cooled.

In article <9rjnbgdppsej1h032qldbdn7ne3mq6bp28@4ax.com>,
<jlarkin@highlandsniptechnology.com> wrote:
<SNIP>
>
>Rough estimate on that box is about 4 watts per cubic inch.

Now you put met into imperial mode. How much btu is that again?

>--
>
>John Larkin Highland Technology, Inc
>
>
>
--
"in our communism country Viet Nam, people are forced to be
alive and in the western country like US, people are free to
die from Covid 19 lol" duc ha
albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst

On 06/06/2021 03:29, jlarkin@highlandsniptechnology.com wrote:
> Suppose I have a bunch of PC boards in a chassis, vertical and
> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> them might be programmable ac/dc load modules.
>
> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> x 4" heat sink, and could space one or more small fans above each, how
> much power might I be able to dump? The host rackmount enclosure will
> have a couple of overall fans too.
>
> The idea is roughly
>
> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>
> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>
> We could set up a breadboard test next week, but I'd like a ballpark
> now.
>
> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> hot, hotter than a CPU would like.
>
> Maybe we could use several mosfets and a few commercial CPU cooler
> things.

These days big electronic loads and battery cyclers usually feed power
back into the AC mains, or into the DC bus that powers other units in
the box, e.g. the load on the output of an inverter under test will feed
power back into the power supply that provides the input to the unit
under test, or the energy from flattening one battery goes into charging
the next one.

e.g.

https://www.chromausa.com/instruments/regenerative-sources-and-loads/

On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

>On 06/06/2021 03:29, jlarkin@highlandsniptechnology.com wrote:
>> Suppose I have a bunch of PC boards in a chassis, vertical and
>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>> them might be programmable ac/dc load modules.
>>
>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>> x 4" heat sink, and could space one or more small fans above each, how
>> much power might I be able to dump? The host rackmount enclosure will
>> have a couple of overall fans too.
>>
>> The idea is roughly
>>
>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>
>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>
>> We could set up a breadboard test next week, but I'd like a ballpark
>> now.
>>
>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>> hot, hotter than a CPU would like.
>>
>> Maybe we could use several mosfets and a few commercial CPU cooler
>> things.
>
>
>
>These days big electronic loads and battery cyclers usually feed power
>back into the AC mains, or into the DC bus that powers other units in
>the box, e.g. the load on the output of an inverter under test will feed
>power back into the power supply that provides the input to the unit
>under test, or the energy from flattening one battery goes into charging
>the next one.
>
>e.g.
>
>https://www.chromausa.com/instruments/regenerative-sources-and-loads/
>

That was suggested, but the MeanWell bulk 48V power supply that we'll
be using can't be back-fed into the AC line.

A dissipative isolated programmable load is nice and simple, but gets
hot.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On 07/06/2021 00:32, jlarkin@highlandsniptechnology.com wrote:
> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
> <lugnut808@spam.yahoo.com> wrote:
>
>> On 06/06/2021 03:29, jlarkin@highlandsniptechnology.com wrote:
>>> Suppose I have a bunch of PC boards in a chassis, vertical and
>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>>> them might be programmable ac/dc load modules.
>>>
>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>>> x 4" heat sink, and could space one or more small fans above each, how
>>> much power might I be able to dump? The host rackmount enclosure will
>>> have a couple of overall fans too.
>>>
>>> The idea is roughly
>>>
>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>>
>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>>
>>> We could set up a breadboard test next week, but I'd like a ballpark
>>> now.
>>>
>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>>> hot, hotter than a CPU would like.
>>>
>>> Maybe we could use several mosfets and a few commercial CPU cooler
>>> things.
>>
>>
>>
>> These days big electronic loads and battery cyclers usually feed power
>> back into the AC mains, or into the DC bus that powers other units in
>> the box, e.g. the load on the output of an inverter under test will feed
>> power back into the power supply that provides the input to the unit
>> under test, or the energy from flattening one battery goes into charging
>> the next one.
>>
>> e.g.
>>
>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
>>
>
> That was suggested, but the MeanWell bulk 48V power supply that we'll
> be using can't be back-fed into the AC line.
>
> A dissipative isolated programmable load is nice and simple, but gets
> hot.

Yes. The one I posted the schematic of in another thread

https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a.pdf

was water-cooled. I was annoyed that nobody makes a compact water block
designed for a single SOT-227B, so I had to make them myself. Machining
and tig-welding pure copper is more annoying than I expected.

Is the device-under-test electrically powered, or where does it get its
energy from ultimately? (Batteries? burning fuel?) If it is ultimately
electrically powered then there may be no need to feed power into the
mains, rather it could go into the DUT supply. You could use an
off-the-shelf isolated DC-DC converter brick, design your "load" to dump
its power into a power-zener, and put the input side of the DC-DC brick
across this zener. Then somehow adjust the amount of load current the
DC-DC brick feeds into the DUT input bus until your power-zener has
negligible but non-zero current flowing in it.

Even if you can't feed the power into the DUT supply or the mains
(because the DUT runs on burning fuel for example) you could still dump
the power into an external resistive load, located somewhere more
convenient.

On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

>On 07/06/2021 00:32, jlarkin@highlandsniptechnology.com wrote:
>> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
>> <lugnut808@spam.yahoo.com> wrote:
>>
>>> On 06/06/2021 03:29, jlarkin@highlandsniptechnology.com wrote:
>>>> Suppose I have a bunch of PC boards in a chassis, vertical and
>>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>>>> them might be programmable ac/dc load modules.
>>>>
>>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>>>> x 4" heat sink, and could space one or more small fans above each, how
>>>> much power might I be able to dump? The host rackmount enclosure will
>>>> have a couple of overall fans too.
>>>>
>>>> The idea is roughly
>>>>
>>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>>>>
>>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>>>
>>>> We could set up a breadboard test next week, but I'd like a ballpark
>>>> now.
>>>>
>>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>>>> hot, hotter than a CPU would like.
>>>>
>>>> Maybe we could use several mosfets and a few commercial CPU cooler
>>>> things.
>>>
>>>
>>>
>>> These days big electronic loads and battery cyclers usually feed power
>>> back into the AC mains, or into the DC bus that powers other units in
>>> the box, e.g. the load on the output of an inverter under test will feed
>>> power back into the power supply that provides the input to the unit
>>> under test, or the energy from flattening one battery goes into charging
>>> the next one.
>>>
>>> e.g.
>>>
>>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
>>>
>>
>> That was suggested, but the MeanWell bulk 48V power supply that we'll
>> be using can't be back-fed into the AC line.
>>
>> A dissipative isolated programmable load is nice and simple, but gets
>> hot.
>
>Yes. The one I posted the schematic of in another thread
>
>https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a.pdf
>
>was water-cooled. I was annoyed that nobody makes a compact water block
>designed for a single SOT-227B, so I had to make them myself. Machining
>and tig-welding pure copper is more annoying than I expected.

My 1400 volt Pockels Cell driver is water cooled. I used an aluminum
block and AlN insulators for the silicon carbide TO247 fets, assuming
my customers would have a cold plate.

>
>Is the device-under-test electrically powered, or where does it get its
>energy from ultimately? (Batteries? burning fuel?) If it is ultimately
>electrically powered then there may be no need to feed power into the
>mains, rather it could go into the DUT supply.

I can't get inside my users' various DUTs. One possible thing to load
is an engine control computer; one is an alternator.

>You could use an
>off-the-shelf isolated DC-DC converter brick, design your "load" to dump
>its power into a power-zener, and put the input side of the DC-DC brick
>across this zener. Then somehow adjust the amount of load current the
>DC-DC brick feeds into the DUT input bus until your power-zener has
>negligible but non-zero current flowing in it.
>

I could have a box-global load somewhere, just to allow my plugig
cards to be dense and not have them get rid of heat themselves. That
would sure complicate life.

>Even if you can't feed the power into the DUT supply or the mains
>(because the DUT runs on burning fuel for example) you could still dump
>the power into an external resistive load, located somewhere more
>convenient.
>

My idea was pretty simple:

https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0

The FPGA will look at the voltage and current sensing isolated ADCs
and play with the gate drive. We can do CV, CC, constant resistance,
or constant power modes, AC or DC. We'll assume that we don't need to
operate below maybe 1.5 volts, which is OK with my customer base;
hence the bridge rectifier. I suppose an ideal (mosfet bridge)
rectifier would be feasible. That would be an interesting circuit.

I'll ask my mechanical guy if maybe we could dump heat into the bottom
of the rackmount box, which is a lot of aluminum. We'd have to
experiment with a mockup to quantify that.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Monday, June 7, 2021 at 6:36:30 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones
> <lugn...@spam.yahoo.com> wrote:
>
> >On 07/06/2021 00:32, jla...@highlandsniptechnology.com wrote:
> >> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
> >> <lugn...@spam.yahoo.com> wrote:
> >>
> >>> On 06/06/2021 03:29, jla...@highlandsniptechnology.com wrote:
> >>>> Suppose I have a bunch of PC boards in a chassis, vertical and
> >>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> >>>> them might be programmable ac/dc load modules.
> >>>>
> >>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> >>>> x 4" heat sink, and could space one or more small fans above each, how
> >>>> much power might I be able to dump? The host rackmount enclosure will
> >>>> have a couple of overall fans too.
> >>>>
> >>>> The idea is roughly
> >>>>
> >>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
> >>>>
> >>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
> >>>>
> >>>> We could set up a breadboard test next week, but I'd like a ballpark
> >>>> now.
> >>>>
> >>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> >>>> hot, hotter than a CPU would like.
> >>>>
> >>>> Maybe we could use several mosfets and a few commercial CPU cooler
> >>>> things.
> >>>
> >>>
> >>>
> >>> These days big electronic loads and battery cyclers usually feed power
> >>> back into the AC mains, or into the DC bus that powers other units in
> >>> the box, e.g. the load on the output of an inverter under test will feed
> >>> power back into the power supply that provides the input to the unit
> >>> under test, or the energy from flattening one battery goes into charging
> >>> the next one.
> >>>
> >>> e.g.
> >>>
> >>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
> >>>
> >>
> >> That was suggested, but the MeanWell bulk 48V power supply that we'll
> >> be using can't be back-fed into the AC line.
> >>
> >> A dissipative isolated programmable load is nice and simple, but gets
> >> hot.
> >
> >Yes. The one I posted the schematic of in another thread
> >
> >https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a..pdf
> >
> >was water-cooled. I was annoyed that nobody makes a compact water block
> >designed for a single SOT-227B, so I had to make them myself. Machining
> >and tig-welding pure copper is more annoying than I expected.
> My 1400 volt Pockels Cell driver is water cooled. I used an aluminum
> block and AlN insulators for the silicon carbide TO247 fets, assuming
> my customers would have a cold plate.
> >
> >Is the device-under-test electrically powered, or where does it get its
> >energy from ultimately? (Batteries? burning fuel?) If it is ultimately
> >electrically powered then there may be no need to feed power into the
> >mains, rather it could go into the DUT supply.
> I can't get inside my users' various DUTs. One possible thing to load
> is an engine control computer; one is an alternator.
> >You could use an
> >off-the-shelf isolated DC-DC converter brick, design your "load" to dump
> >its power into a power-zener, and put the input side of the DC-DC brick
> >across this zener. Then somehow adjust the amount of load current the
> >DC-DC brick feeds into the DUT input bus until your power-zener has
> >negligible but non-zero current flowing in it.
> >
> I could have a box-global load somewhere, just to allow my plugig
> cards to be dense and not have them get rid of heat themselves. That
> would sure complicate life.
> >Even if you can't feed the power into the DUT supply or the mains
> >(because the DUT runs on burning fuel for example) you could still dump
> >the power into an external resistive load, located somewhere more
> >convenient.
> >
> My idea was pretty simple:
>
> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>
> The FPGA will look at the voltage and current sensing isolated ADCs
> and play with the gate drive. We can do CV, CC, constant resistance,
> or constant power modes, AC or DC. We'll assume that we don't need to
> operate below maybe 1.5 volts, which is OK with my customer base;
> hence the bridge rectifier. I suppose an ideal (mosfet bridge)
> rectifier would be feasible. That would be an interesting circuit.

Is this the same module plug into the over-voltage-protection-less power supply? In this case, it would be simple to just insert an OV cutoff mosfet, driven by your FPGA fabric. I use ARM micro to do it, but the idea is the same. In either case, 3v driven mosfet would be ideal:

Diode DMN3020UTS TSSOP-8 14A
Diode DMN2015UFDF DFN2020-6 14A
Vishay SiA448DJ SC-70-8L 12A
AlpOmg AO6404 TSOP6 8.6A
Rohm RQ1C075UN TSMT8 7.5A
ST STT5N2VH5 SOT23 5A

On Mon, 7 Jun 2021 06:45:42 -0700 (PDT), Ed Lee
<edward.ming.lee@gmail.com> wrote:

>On Monday, June 7, 2021 at 6:36:30 AM UTC-7, jla...@highlandsniptechnology.com wrote:
>> On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones
>> <lugn...@spam.yahoo.com> wrote:
>>
>> >On 07/06/2021 00:32, jla...@highlandsniptechnology.com wrote:
>> >> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
>> >> <lugn...@spam.yahoo.com> wrote:
>> >>
>> >>> On 06/06/2021 03:29, jla...@highlandsniptechnology.com wrote:
>> >>>> Suppose I have a bunch of PC boards in a chassis, vertical and
>> >>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>> >>>> them might be programmable ac/dc load modules.
>> >>>>
>> >>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>> >>>> x 4" heat sink, and could space one or more small fans above each, how
>> >>>> much power might I be able to dump? The host rackmount enclosure will
>> >>>> have a couple of overall fans too.
>> >>>>
>> >>>> The idea is roughly
>> >>>>
>> >>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>> >>>>
>> >>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>> >>>>
>> >>>> We could set up a breadboard test next week, but I'd like a ballpark
>> >>>> now.
>> >>>>
>> >>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>> >>>> hot, hotter than a CPU would like.
>> >>>>
>> >>>> Maybe we could use several mosfets and a few commercial CPU cooler
>> >>>> things.
>> >>>
>> >>>
>> >>>
>> >>> These days big electronic loads and battery cyclers usually feed power
>> >>> back into the AC mains, or into the DC bus that powers other units in
>> >>> the box, e.g. the load on the output of an inverter under test will feed
>> >>> power back into the power supply that provides the input to the unit
>> >>> under test, or the energy from flattening one battery goes into charging
>> >>> the next one.
>> >>>
>> >>> e.g.
>> >>>
>> >>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
>> >>>
>> >>
>> >> That was suggested, but the MeanWell bulk 48V power supply that we'll
>> >> be using can't be back-fed into the AC line.
>> >>
>> >> A dissipative isolated programmable load is nice and simple, but gets
>> >> hot.
>> >
>> >Yes. The one I posted the schematic of in another thread
>> >
>> >https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a.pdf
>> >
>> >was water-cooled. I was annoyed that nobody makes a compact water block
>> >designed for a single SOT-227B, so I had to make them myself. Machining
>> >and tig-welding pure copper is more annoying than I expected.
>> My 1400 volt Pockels Cell driver is water cooled. I used an aluminum
>> block and AlN insulators for the silicon carbide TO247 fets, assuming
>> my customers would have a cold plate.
>> >
>> >Is the device-under-test electrically powered, or where does it get its
>> >energy from ultimately? (Batteries? burning fuel?) If it is ultimately
>> >electrically powered then there may be no need to feed power into the
>> >mains, rather it could go into the DUT supply.
>> I can't get inside my users' various DUTs. One possible thing to load
>> is an engine control computer; one is an alternator.
>> >You could use an
>> >off-the-shelf isolated DC-DC converter brick, design your "load" to dump
>> >its power into a power-zener, and put the input side of the DC-DC brick
>> >across this zener. Then somehow adjust the amount of load current the
>> >DC-DC brick feeds into the DUT input bus until your power-zener has
>> >negligible but non-zero current flowing in it.
>> >
>> I could have a box-global load somewhere, just to allow my plugig
>> cards to be dense and not have them get rid of heat themselves. That
>> would sure complicate life.
>> >Even if you can't feed the power into the DUT supply or the mains
>> >(because the DUT runs on burning fuel for example) you could still dump
>> >the power into an external resistive load, located somewhere more
>> >convenient.
>> >
>> My idea was pretty simple:
>>
>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>>
>> The FPGA will look at the voltage and current sensing isolated ADCs
>> and play with the gate drive. We can do CV, CC, constant resistance,
>> or constant power modes, AC or DC. We'll assume that we don't need to
>> operate below maybe 1.5 volts, which is OK with my customer base;
>> hence the bridge rectifier. I suppose an ideal (mosfet bridge)
>> rectifier would be feasible. That would be an interesting circuit.
>
>Is this the same module plug into the over-voltage-protection-less power supply? In this case, it would be simple to just insert an OV cutoff mosfet, driven by your FPGA fabric. I use ARM micro to do it, but the idea is the same. In either case, 3v driven mosfet would be ideal:
>
>Diode DMN3020UTS TSSOP-8 14A
>Diode DMN2015UFDF DFN2020-6 14A
>Vishay SiA448DJ SC-70-8L 12A
>AlpOmg AO6404 TSOP6 8.6A
>Rohm RQ1C075UN TSMT8 7.5A
>ST STT5N2VH5 SOT23 5A

Are we talking about the mosfet bridge rectifier?

LT4320 is interesting but flawed.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Monday, June 7, 2021 at 8:35:33 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> On Mon, 7 Jun 2021 06:45:42 -0700 (PDT), Ed Lee
> <edward....@gmail.com> wrote:
>
> >On Monday, June 7, 2021 at 6:36:30 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> >> On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones
> >> <lugn...@spam.yahoo.com> wrote:
> >>
> >> >On 07/06/2021 00:32, jla...@highlandsniptechnology.com wrote:
> >> >> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
> >> >> <lugn...@spam.yahoo.com> wrote:
> >> >>
> >> >>> On 06/06/2021 03:29, jla...@highlandsniptechnology.com wrote:
> >> >>>> Suppose I have a bunch of PC boards in a chassis, vertical and
> >> >>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> >> >>>> them might be programmable ac/dc load modules.
> >> >>>>
> >> >>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> >> >>>> x 4" heat sink, and could space one or more small fans above each, how
> >> >>>> much power might I be able to dump? The host rackmount enclosure will
> >> >>>> have a couple of overall fans too.
> >> >>>>
> >> >>>> The idea is roughly
> >> >>>>
> >> >>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
> >> >>>>
> >> >>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
> >> >>>>
> >> >>>> We could set up a breadboard test next week, but I'd like a ballpark
> >> >>>> now.
> >> >>>>
> >> >>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> >> >>>> hot, hotter than a CPU would like.
> >> >>>>
> >> >>>> Maybe we could use several mosfets and a few commercial CPU cooler
> >> >>>> things.
> >> >>>
> >> >>>
> >> >>>
> >> >>> These days big electronic loads and battery cyclers usually feed power
> >> >>> back into the AC mains, or into the DC bus that powers other units in
> >> >>> the box, e.g. the load on the output of an inverter under test will feed
> >> >>> power back into the power supply that provides the input to the unit
> >> >>> under test, or the energy from flattening one battery goes into charging
> >> >>> the next one.
> >> >>>
> >> >>> e.g.
> >> >>>
> >> >>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
> >> >>>
> >> >>
> >> >> That was suggested, but the MeanWell bulk 48V power supply that we'll
> >> >> be using can't be back-fed into the AC line.
> >> >>
> >> >> A dissipative isolated programmable load is nice and simple, but gets
> >> >> hot.
> >> >
> >> >Yes. The one I posted the schematic of in another thread
> >> >
> >> >https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a.pdf
> >> >
> >> >was water-cooled. I was annoyed that nobody makes a compact water block
> >> >designed for a single SOT-227B, so I had to make them myself. Machining
> >> >and tig-welding pure copper is more annoying than I expected.
> >> My 1400 volt Pockels Cell driver is water cooled. I used an aluminum
> >> block and AlN insulators for the silicon carbide TO247 fets, assuming
> >> my customers would have a cold plate.
> >> >
> >> >Is the device-under-test electrically powered, or where does it get its
> >> >energy from ultimately? (Batteries? burning fuel?) If it is ultimately
> >> >electrically powered then there may be no need to feed power into the
> >> >mains, rather it could go into the DUT supply.
> >> I can't get inside my users' various DUTs. One possible thing to load
> >> is an engine control computer; one is an alternator.
> >> >You could use an
> >> >off-the-shelf isolated DC-DC converter brick, design your "load" to dump
> >> >its power into a power-zener, and put the input side of the DC-DC brick
> >> >across this zener. Then somehow adjust the amount of load current the
> >> >DC-DC brick feeds into the DUT input bus until your power-zener has
> >> >negligible but non-zero current flowing in it.
> >> >
> >> I could have a box-global load somewhere, just to allow my plugig
> >> cards to be dense and not have them get rid of heat themselves. That
> >> would sure complicate life.
> >> >Even if you can't feed the power into the DUT supply or the mains
> >> >(because the DUT runs on burning fuel for example) you could still dump
> >> >the power into an external resistive load, located somewhere more
> >> >convenient.
> >> >
> >> My idea was pretty simple:
> >>
> >> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
> >>
> >> The FPGA will look at the voltage and current sensing isolated ADCs
> >> and play with the gate drive. We can do CV, CC, constant resistance,
> >> or constant power modes, AC or DC. We'll assume that we don't need to
> >> operate below maybe 1.5 volts, which is OK with my customer base;
> >> hence the bridge rectifier. I suppose an ideal (mosfet bridge)
> >> rectifier would be feasible. That would be an interesting circuit.
> >
> >Is this the same module plug into the over-voltage-protection-less power supply? In this case, it would be simple to just insert an OV cutoff mosfet, driven by your FPGA fabric. I use ARM micro to do it, but the idea is the same. In either case, 3v driven mosfet would be ideal:
> >
> >Diode DMN3020UTS TSSOP-8 14A
> >Diode DMN2015UFDF DFN2020-6 14A
> >Vishay SiA448DJ SC-70-8L 12A
> >AlpOmg AO6404 TSOP6 8.6A
> >Rohm RQ1C075UN TSMT8 7.5A
> >ST STT5N2VH5 SOT23 5A
> Are we talking about the mosfet bridge rectifier?

Yes, you can integrate the logic into the bridge rectifier, or just another high side switch.

Easy enough to implement Forward, Backward or Off for the rectifier.

On Mon, 7 Jun 2021 09:03:32 -0700 (PDT), Ed Lee
<edward.ming.lee@gmail.com> wrote:

>On Monday, June 7, 2021 at 8:35:33 AM UTC-7, jla...@highlandsniptechnology.com wrote:
>> On Mon, 7 Jun 2021 06:45:42 -0700 (PDT), Ed Lee
>> <edward....@gmail.com> wrote:
>>
>> >On Monday, June 7, 2021 at 6:36:30 AM UTC-7, jla...@highlandsniptechnology.com wrote:
>> >> On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones
>> >> <lugn...@spam.yahoo.com> wrote:
>> >>
>> >> >On 07/06/2021 00:32, jla...@highlandsniptechnology.com wrote:
>> >> >> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
>> >> >> <lugn...@spam.yahoo.com> wrote:
>> >> >>
>> >> >>> On 06/06/2021 03:29, jla...@highlandsniptechnology.com wrote:
>> >> >>>> Suppose I have a bunch of PC boards in a chassis, vertical and
>> >> >>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
>> >> >>>> them might be programmable ac/dc load modules.
>> >> >>>>
>> >> >>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
>> >> >>>> x 4" heat sink, and could space one or more small fans above each, how
>> >> >>>> much power might I be able to dump? The host rackmount enclosure will
>> >> >>>> have a couple of overall fans too.
>> >> >>>>
>> >> >>>> The idea is roughly
>> >> >>>>
>> >> >>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
>> >> >>>>
>> >> >>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>> >> >>>>
>> >> >>>> We could set up a breadboard test next week, but I'd like a ballpark
>> >> >>>> now.
>> >> >>>>
>> >> >>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
>> >> >>>> hot, hotter than a CPU would like.
>> >> >>>>
>> >> >>>> Maybe we could use several mosfets and a few commercial CPU cooler
>> >> >>>> things.
>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>> These days big electronic loads and battery cyclers usually feed power
>> >> >>> back into the AC mains, or into the DC bus that powers other units in
>> >> >>> the box, e.g. the load on the output of an inverter under test will feed
>> >> >>> power back into the power supply that provides the input to the unit
>> >> >>> under test, or the energy from flattening one battery goes into charging
>> >> >>> the next one.
>> >> >>>
>> >> >>> e.g.
>> >> >>>
>> >> >>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
>> >> >>>
>> >> >>
>> >> >> That was suggested, but the MeanWell bulk 48V power supply that we'll
>> >> >> be using can't be back-fed into the AC line.
>> >> >>
>> >> >> A dissipative isolated programmable load is nice and simple, but gets
>> >> >> hot.
>> >> >
>> >> >Yes. The one I posted the schematic of in another thread
>> >> >
>> >> >https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a.pdf
>> >> >
>> >> >was water-cooled. I was annoyed that nobody makes a compact water block
>> >> >designed for a single SOT-227B, so I had to make them myself. Machining
>> >> >and tig-welding pure copper is more annoying than I expected.
>> >> My 1400 volt Pockels Cell driver is water cooled. I used an aluminum
>> >> block and AlN insulators for the silicon carbide TO247 fets, assuming
>> >> my customers would have a cold plate.
>> >> >
>> >> >Is the device-under-test electrically powered, or where does it get its
>> >> >energy from ultimately? (Batteries? burning fuel?) If it is ultimately
>> >> >electrically powered then there may be no need to feed power into the
>> >> >mains, rather it could go into the DUT supply.
>> >> I can't get inside my users' various DUTs. One possible thing to load
>> >> is an engine control computer; one is an alternator.
>> >> >You could use an
>> >> >off-the-shelf isolated DC-DC converter brick, design your "load" to dump
>> >> >its power into a power-zener, and put the input side of the DC-DC brick
>> >> >across this zener. Then somehow adjust the amount of load current the
>> >> >DC-DC brick feeds into the DUT input bus until your power-zener has
>> >> >negligible but non-zero current flowing in it.
>> >> >
>> >> I could have a box-global load somewhere, just to allow my plugig
>> >> cards to be dense and not have them get rid of heat themselves. That
>> >> would sure complicate life.
>> >> >Even if you can't feed the power into the DUT supply or the mains
>> >> >(because the DUT runs on burning fuel for example) you could still dump
>> >> >the power into an external resistive load, located somewhere more
>> >> >convenient.
>> >> >
>> >> My idea was pretty simple:
>> >>
>> >> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
>> >>
>> >> The FPGA will look at the voltage and current sensing isolated ADCs
>> >> and play with the gate drive. We can do CV, CC, constant resistance,
>> >> or constant power modes, AC or DC. We'll assume that we don't need to
>> >> operate below maybe 1.5 volts, which is OK with my customer base;
>> >> hence the bridge rectifier. I suppose an ideal (mosfet bridge)
>> >> rectifier would be feasible. That would be an interesting circuit.
>> >
>> >Is this the same module plug into the over-voltage-protection-less power supply? In this case, it would be simple to just insert an OV cutoff mosfet, driven by your FPGA fabric. I use ARM micro to do it, but the idea is the same. In either case, 3v driven mosfet would be ideal:
>> >
>> >Diode DMN3020UTS TSSOP-8 14A
>> >Diode DMN2015UFDF DFN2020-6 14A
>> >Vishay SiA448DJ SC-70-8L 12A
>> >AlpOmg AO6404 TSOP6 8.6A
>> >Rohm RQ1C075UN TSMT8 7.5A
>> >ST STT5N2VH5 SOT23 5A
>> Are we talking about the mosfet bridge rectifier?
>
>Yes, you can integrate the logic into the bridge rectifier, or just another high side switch.
>
>Easy enough to implement Forward, Backward or Off for the rectifier.

I think it needs four floating gate drivers (with n-fets) and some
sensing stuff. The voltage ADC could sense the input polarity. High
hassle level.

I could put two current limiters back-to-back with no rectifier, but
that makes the thermals worse.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Monday, June 7, 2021 at 9:31:32 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> On Mon, 7 Jun 2021 09:03:32 -0700 (PDT), Ed Lee
> <edward....@gmail.com> wrote:
>
> >On Monday, June 7, 2021 at 8:35:33 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> >> On Mon, 7 Jun 2021 06:45:42 -0700 (PDT), Ed Lee
> >> <edward....@gmail.com> wrote:
> >>
> >> >On Monday, June 7, 2021 at 6:36:30 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> >> >> On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones
> >> >> <lugn...@spam.yahoo.com> wrote:
> >> >>
> >> >> >On 07/06/2021 00:32, jla...@highlandsniptechnology.com wrote:
> >> >> >> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones
> >> >> >> <lugn...@spam.yahoo.com> wrote:
> >> >> >>
> >> >> >>> On 06/06/2021 03:29, jla...@highlandsniptechnology.com wrote:
> >> >> >>>> Suppose I have a bunch of PC boards in a chassis, vertical and
> >> >> >>>> parallel, about 3" x 12" each, maybe 1.25 inch centers. One or more of
> >> >> >>>> them might be programmable ac/dc load modules.
> >> >> >>>>
> >> >> >>>> Some of you guys work with cooling CPUs and such. If I had, say, a 3"
> >> >> >>>> x 4" heat sink, and could space one or more small fans above each, how
> >> >> >>>> much power might I be able to dump? The host rackmount enclosure will
> >> >> >>>> have a couple of overall fans too.
> >> >> >>>>
> >> >> >>>> The idea is roughly
> >> >> >>>>
> >> >> >>>> https://www.dropbox.com/s/eugav7g0co0z4nb/P940_module.jpg?dl=0
> >> >> >>>>
> >> >> >>>> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
> >> >> >>>>
> >> >> >>>> We could set up a breadboard test next week, but I'd like a ballpark
> >> >> >>>> now.
> >> >> >>>>
> >> >> >>>> Is, say, 100 to 200 watts feasible? It could be allowed to get pretty
> >> >> >>>> hot, hotter than a CPU would like.
> >> >> >>>>
> >> >> >>>> Maybe we could use several mosfets and a few commercial CPU cooler
> >> >> >>>> things.
> >> >> >>>
> >> >> >>>
> >> >> >>>
> >> >> >>> These days big electronic loads and battery cyclers usually feed power
> >> >> >>> back into the AC mains, or into the DC bus that powers other units in
> >> >> >>> the box, e.g. the load on the output of an inverter under test will feed
> >> >> >>> power back into the power supply that provides the input to the unit
> >> >> >>> under test, or the energy from flattening one battery goes into charging
> >> >> >>> the next one.
> >> >> >>>
> >> >> >>> e.g.
> >> >> >>>
> >> >> >>> https://www.chromausa.com/instruments/regenerative-sources-and-loads/
> >> >> >>>
> >> >> >>
> >> >> >> That was suggested, but the MeanWell bulk 48V power supply that we'll
> >> >> >> be using can't be back-fed into the AC line.
> >> >> >>
> >> >> >> A dissipative isolated programmable load is nice and simple, but gets
> >> >> >> hot.
> >> >> >
> >> >> >Yes. The one I posted the schematic of in another thread
> >> >> >
> >> >> >https://bitbucket.org/chrisgj198/projects/raw/master/eload/kicad/eload1a.pdf
> >> >> >
> >> >> >was water-cooled. I was annoyed that nobody makes a compact water block
> >> >> >designed for a single SOT-227B, so I had to make them myself. Machining
> >> >> >and tig-welding pure copper is more annoying than I expected.
> >> >> My 1400 volt Pockels Cell driver is water cooled. I used an aluminum
> >> >> block and AlN insulators for the silicon carbide TO247 fets, assuming
> >> >> my customers would have a cold plate.
> >> >> >
> >> >> >Is the device-under-test electrically powered, or where does it get its
> >> >> >energy from ultimately? (Batteries? burning fuel?) If it is ultimately
> >> >> >electrically powered then there may be no need to feed power into the
> >> >> >mains, rather it could go into the DUT supply.
> >> >> I can't get inside my users' various DUTs. One possible thing to load
> >> >> is an engine control computer; one is an alternator.
> >> >> >You could use an
> >> >> >off-the-shelf isolated DC-DC converter brick, design your "load" to dump
> >> >> >its power into a power-zener, and put the input side of the DC-DC brick
> >> >> >across this zener. Then somehow adjust the amount of load current the
> >> >> >DC-DC brick feeds into the DUT input bus until your power-zener has
> >> >> >negligible but non-zero current flowing in it.
> >> >> >
> >> >> I could have a box-global load somewhere, just to allow my plugig
> >> >> cards to be dense and not have them get rid of heat themselves. That
> >> >> would sure complicate life.
> >> >> >Even if you can't feed the power into the DUT supply or the mains
> >> >> >(because the DUT runs on burning fuel for example) you could still dump
> >> >> >the power into an external resistive load, located somewhere more
> >> >> >convenient.
> >> >> >
> >> >> My idea was pretty simple:
> >> >>
> >> >> https://www.dropbox.com/s/aouza5ht8fxcex4/P940_load.jpg?dl=0
> >> >>
> >> >> The FPGA will look at the voltage and current sensing isolated ADCs
> >> >> and play with the gate drive. We can do CV, CC, constant resistance,
> >> >> or constant power modes, AC or DC. We'll assume that we don't need to
> >> >> operate below maybe 1.5 volts, which is OK with my customer base;
> >> >> hence the bridge rectifier. I suppose an ideal (mosfet bridge)
> >> >> rectifier would be feasible. That would be an interesting circuit.
> >> >
> >> >Is this the same module plug into the over-voltage-protection-less power supply? In this case, it would be simple to just insert an OV cutoff mosfet, driven by your FPGA fabric. I use ARM micro to do it, but the idea is the same. In either case, 3v driven mosfet would be ideal:
> >> >
> >> >Diode DMN3020UTS TSSOP-8 14A
> >> >Diode DMN2015UFDF DFN2020-6 14A
> >> >Vishay SiA448DJ SC-70-8L 12A
> >> >AlpOmg AO6404 TSOP6 8.6A
> >> >Rohm RQ1C075UN TSMT8 7.5A
> >> >ST STT5N2VH5 SOT23 5A
> >> Are we talking about the mosfet bridge rectifier?
> >
> >Yes, you can integrate the logic into the bridge rectifier, or just another high side switch.
> >
> >Easy enough to implement Forward, Backward or Off for the rectifier.
> I think it needs four floating gate drivers (with n-fets) and some
> sensing stuff. The voltage ADC could sense the input polarity. High
> hassle level.

I use PC123 or high voltage equivalent (opto isolators) to implement floating gate drivers. It can totally isolate the electronics from the power source. That way, i can monitor and control upto 20v power source.

On Tuesday, June 8, 2021 at 2:53:00 AM UTC+10, Ed Lee wrote:
> On Monday, June 7, 2021 at 9:31:32 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> > On Mon, 7 Jun 2021 09:03:32 -0700 (PDT), Ed Lee
> > <edward....@gmail.com> wrote:
> >
> > >On Monday, June 7, 2021 at 8:35:33 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> > >> On Mon, 7 Jun 2021 06:45:42 -0700 (PDT), Ed Lee <edward....@gmail.com> wrote:
> > >> >On Monday, June 7, 2021 at 6:36:30 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> > >> >> On Mon, 7 Jun 2021 21:51:59 +1000, Chris Jones <lugn...@spam.yahoo.com> wrote:
> > >> >> >On 07/06/2021 00:32, jla...@highlandsniptechnology.com wrote:
> > >> >> >> On Sun, 6 Jun 2021 22:44:51 +1000, Chris Jones <lugn...@spam.yahoo.com> wrote:
> > >> >> >>> On 06/06/2021 03:29, jla...@highlandsniptechnology.com wrote:

<snip>

> I use PC123 or high voltage equivalent (opto isolators) to implement floating gate drivers. It can totally isolate the electronics from the power source. That way, i can monitor and control up to 20v power source.

Inductive isolation is usually cheaper, but bulkier, and usually takes more design time.

--
Bill Sloman, Sydney