load bank puzzle...

[Mike Monett VE3BTI]

Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:

There is a lot that can go wrong, often pilot error like the one I
followed last week that crashed in a field near Schiphol airport,
pilot had one engine throttled down.. (propeller 2 engine plane)
without knowing it (he did it himself) so when steering towards the
runway the plane tilted one way and he lost control..

There was one similar in Nepal, probably caused by the first officer
pulling the wrong handle feathering the engines instead of lowering the
flaps, like because he would normally be flying in the left seat as a
captain, but on this flight he was an instructor so he was in the right
seat...

Nepal ATR 72 Crash 15 Jan 2023
https://www.youtube.com/watch?v=OnuVPUsz9VE

Flight YT-691 Nepal Yeti Airlines ATR 72 Crash First Explanation by
the ATR Airline Pilot
https://www.youtube.com/watch?v=SOTWCrjbHN8

An unbelievable mistake | Yeti Airlines flight 691
https://www.youtube.com/watch?v=wIlO-TBDyaw

Preliminary Report - Yeti Airlines ATR 72 Plane Crash Pokhara Nepal
Jan 15 2023 #planecrash #pirep
https://www.youtube.com/watch?v=5RsOlS93lxc

HUMAN ERROR or MECHANICAL?! | Yeti Airlines flight YT691 illustrated
https://www.youtube.com/watch?v=Ppo73zeAvDo




--
MRM

 

[Jan Panteltje]

On a sunny day (Sat, 18 Mar 2023 13:38:44 -0700 (PDT)) it happened Lasse
Langwadt Christensen <langwadt@fonz.dk> wrote in
<9628b72f-aa02-40d2-b1e4-c5087e2c7083n@googlegroups.com>:

lørdag den 18. marts 2023 kl. 20.30.07 UTC+1 skrev Jan Panteltje:
On a sunny day (Sat, 18 Mar 2023 10:28:46 -0700) it happened John Larkin=

jla...@highlandSNIPMEtechnology.com> wrote in
kisb1ipbum7dulpqh...@4ax.com>:
On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <al...@comet.invalid
wrote:
I have no idea what a FADEC is or what its internals are
so I looked it up:
https://en.wikipedia.org/wiki/FADEC

Now I will stop flying!!!!

Each FADEC is redundant, and gets power from both the airframe DC
supply and from a dual alternator on its engine. Thet are very
reliable. Most engine problems are mechanical or fuel related. Birds
are bad in jet engines.

We sell alternator simulators that are used to test FADECs, which
furtunately people buy two at a time. It\'s kind of interesting, since
a PM alternator is basically a current source and the FADECs regulate
by shorting them. Our rev A box tended to blow up.


Some small planes have full-plane parachutes. They land hard but
survivably.
Engine on fire, we circled and dumped fuel, then landed safely on one e=
ngine.

Planes can fly on one engine, as long as the failed one doesn\'t toss
blades and tear a wing off or something like that. They have
\"containment\" that usually works. Engines are tested to destruction to=

make sure the blades stay inside.
There is a series on German satellite TV about plane crashes that happene=
d and they go into all the details
and follow the guys evaluating what\'s left.. to find the cause.

\"Aircrash investigation\" I\'d guess, they are not bad but there\'s a few yout=
ube channels*
with actual pilots going through the accident reports, watching those make =
you realise
the TV shows are often far from accurate

No, not Aircrash investigation, forgot he name, German channel, think it was called \'Mayday\' or something?
Will let you know when I hit it again (hundreds of channels here)

*to mention a few, Mentour Pilot and blancolirio

There is a lot that can go wrong, often pilot error like the one I follow=
ed
last week that crashed in a field near Schiphol airport,
pilot had one engine throttled down.. (propeller 2 engine plane) without =
knowing it (he did it himself)
so when steering towards the runway the plane tilted one way and he lost =
control..

There was one similar in Nepal, probably caused by the first officer pullin=
g the wrong handle feathering the engines
instead of lowering the flaps, like because he would normally be flying in =
the left seat as a captain, but on this flight
he was an instructor so he was in the right seat...

Checklist are interesting too, I have a checklist for some thing I do,
I went through it and sure enough one day I found out I had missed something...

There was this airplane .. they went through the takeoff checklist but were interrupted
by a stewardess making an appointment for the evening with one of the pilots (voice recorder was recovered)
so they forgot to set the flaps for takeoff.
Hundreds died, crashed at the end of the runway, ball of fire (full of fuel).

You want a computer there saying: \"Hey dummy, set your flaps or I will do it for you !!\"
Procedure is: Nobody allowed in the cockpit during prepare for takeoff, but human relations...

 

[Jasen Betts]

On 2023-03-19, Jan Panteltje <alien@comet.invalid> wrote:

On a sunny day (Sat, 18 Mar 2023 13:38:44 -0700 (PDT)) it happened Lasse
Langwadt Christensen <langwadt@fonz.dk> wrote in
9628b72f-aa02-40d2-b1e4-c5087e2c7083n@googlegroups.com>:

lørdag den 18. marts 2023 kl. 20.30.07 UTC+1 skrev Jan Panteltje:
On a sunny day (Sat, 18 Mar 2023 10:28:46 -0700) it happened John Larkin=

jla...@highlandSNIPMEtechnology.com> wrote in
kisb1ipbum7dulpqh...@4ax.com>:
On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <al...@comet.invalid
wrote:
I have no idea what a FADEC is or what its internals are
so I looked it up:
7>>> >> https://en.wikipedia.org/wiki/FADEC

Now I will stop flying!!!!

Each FADEC is redundant, and gets power from both the airframe DC
supply and from a dual alternator on its engine. Thet are very
reliable. Most engine problems are mechanical or fuel related. Birds
are bad in jet engines.

We sell alternator simulators that are used to test FADECs, which
furtunately people buy two at a time. It\'s kind of interesting, since
a PM alternator is basically a current source and the FADECs regulate
by shorting them. Our rev A box tended to blow up.


Some small planes have full-plane parachutes. They land hard but
survivably.
Engine on fire, we circled and dumped fuel, then landed safely on one e=
ngine.

Planes can fly on one engine, as long as the failed one doesn\'t toss
blades and tear a wing off or something like that. They have
\"containment\" that usually works. Engines are tested to destruction to=

make sure the blades stay inside.
There is a series on German satellite TV about plane crashes that happene=
d and they go into all the details
and follow the guys evaluating what\'s left.. to find the cause.

\"Aircrash investigation\" I\'d guess, they are not bad but there\'s a few yout=
ube channels*
with actual pilots going through the accident reports, watching those make =
you realise
the TV shows are often far from accurate

No, not Aircrash investigation, forgot he name, German channel, think it was called \'Mayday\' or something?
Will let you know when I hit it again (hundreds of channels here)

yes that one:

\"Mayday\", known as \"Air Crash Investigation\"
outside of the United States and Canada and
also known as \"Mayday: Air Disaster\"

They read the investigation report, do some CGI, reenactments,
show some report footage, news footage, photos, possibly do a
scene visit, and interview some of the people involved.

Also available in German:

https://de.wikipedia.org/wiki/Mayday_%E2%80%93_Alarm_im_Cockpit/Episodenliste

--
Jasen.
🇺🇦 Слава Україні

 

[Jan Panteltje]

On a sunny day (Sun, 19 Mar 2023 10:28:46 -0000 (UTC)) it happened Jasen Betts
<usenet@revmaps.no-ip.org> wrote in <tv6o4u$i0f$2@gonzo.revmaps.no-ip.org>:

On 2023-03-19, Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Sat, 18 Mar 2023 13:38:44 -0700 (PDT)) it happened Lasse
Langwadt Christensen <langwadt@fonz.dk> wrote in
9628b72f-aa02-40d2-b1e4-c5087e2c7083n@googlegroups.com>:

lørdag den 18. marts 2023 kl. 20.30.07 UTC+1 skrev Jan Panteltje:
On a sunny day (Sat, 18 Mar 2023 10:28:46 -0700) it happened John Larkin=

jla...@highlandSNIPMEtechnology.com> wrote in
kisb1ipbum7dulpqh...@4ax.com>:
On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <al...@comet.invalid
wrote:
I have no idea what a FADEC is or what its internals are
so I looked it up:
7>>> >> https://en.wikipedia.org/wiki/FADEC

Now I will stop flying!!!!

Each FADEC is redundant, and gets power from both the airframe DC
supply and from a dual alternator on its engine. Thet are very
reliable. Most engine problems are mechanical or fuel related. Birds
are bad in jet engines.

We sell alternator simulators that are used to test FADECs, which
furtunately people buy two at a time. It\'s kind of interesting, since
a PM alternator is basically a current source and the FADECs regulate
by shorting them. Our rev A box tended to blow up.


Some small planes have full-plane parachutes. They land hard but
survivably.
Engine on fire, we circled and dumped fuel, then landed safely on one e=
ngine.

Planes can fly on one engine, as long as the failed one doesn\'t toss
blades and tear a wing off or something like that. They have
\"containment\" that usually works. Engines are tested to destruction to=

make sure the blades stay inside.
There is a series on German satellite TV about plane crashes that happene=
d and they go into all the details
and follow the guys evaluating what\'s left.. to find the cause.

\"Aircrash investigation\" I\'d guess, they are not bad but there\'s a few yout=
ube channels*
with actual pilots going through the accident reports, watching those make =
you realise
the TV shows are often far from accurate

No, not Aircrash investigation, forgot he name, German channel, think it was called \'Mayday\' or something?
Will let you know when I hit it again (hundreds of channels here)

yes that one:

\"Mayday\", known as \"Air Crash Investigation\"
outside of the United States and Canada and
also known as \"Mayday: Air Disaster\"

They read the investigation report, do some CGI, reenactments,
show some report footage, news footage, photos, possibly do a
scene visit, and interview some of the people involved.

Also available in German:

https://de.wikipedia.org/wiki/Mayday_%E2%80%93_Alarm_im_Cockpit/Episodenliste

Yes, looks like it!

I see a next one scheduled on March 20 2023
I will check the satellite list I use
https://www.tvdirekt.de/programmsuche.html
search for Mayday
wow, its today at 13:55
19.03.2023 - Sonntag13:55
Mayday
Dokureihe, CDN 2019
Staffel: 19 / Folge: 3
Laufzeit: 50 Minuten
Original-Titel: Mayday: Air Disaster
Mit: Jonathan Aris, Ian Kilburn, Ira Donald Henderson, Marc Hickox, Irena Huljak, David Tompa
Regie: Mark Mainguy
Im April 1994 startet der KLM-Cityhopper-Flug 433 vom Amsterdamer Flughafen Shiphol ins walisische Cardiff. Um den Passagieren eine ruhige Fahrt ...

That is a repeat of the 2 engine propellor plane case I mentioned: Amsterdam Cardiff


20.03.2023 - Montag
 00:15
On monday the next one:
Mayday
Dokureihe, CDN 2019
Staffel: 19 / Folge: 9
Laufzeit: 35 Minuten
Original-Titel: Mayday: Air Disaster
Mit: Jonathan Aris, John Elios, Juan Carlos Velis, John Tokatlidis, Jorge Molina, Alexandra Castillo
Regie: Mark Mainguy
Der brasilianische Fußball-Erstligist Chapecoense erreichte 2016 völlig überraschend das Finale des Copa Sudaméricana. Doch auf dem Weg zum Spiel ...

It is also on \'Welt\' (different schedule but I can receive that).


kingofsat.net is my satellite help:
https://en.kingofsat.net/find.php?&lim=20&standard=All&ordre=freq&question=NATIONAL-GEOGRAPHIC&filtre=no&aff=zap
should be able to receive it on hotbird and astra and even badr5 28 East
steerable dish here

Thanks

 

[Lasse Langwadt Christensen]

søndag den 19. marts 2023 kl. 08.00.28 UTC+1 skrev Jan Panteltje:

On a sunny day (Sat, 18 Mar 2023 13:38:44 -0700 (PDT)) it happened Lasse
Langwadt Christensen <lang...@fonz.dk> wrote in
9628b72f-aa02-40d2...@googlegroups.com>:
lørdag den 18. marts 2023 kl. 20.30.07 UTC+1 skrev Jan Panteltje:
On a sunny day (Sat, 18 Mar 2023 10:28:46 -0700) it happened John Larkin
jla...@highlandSNIPMEtechnology.com> wrote in
kisb1ipbum7dulpqh...@4ax.com>:
On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <al...@comet.invalid
wrote:
I have no idea what a FADEC is or what its internals are
so I looked it up:
https://en.wikipedia.org/wiki/FADEC

Now I will stop flying!!!!

Each FADEC is redundant, and gets power from both the airframe DC
supply and from a dual alternator on its engine. Thet are very
reliable. Most engine problems are mechanical or fuel related. Birds
are bad in jet engines.

We sell alternator simulators that are used to test FADECs, which
furtunately people buy two at a time. It\'s kind of interesting, since
a PM alternator is basically a current source and the FADECs regulate
by shorting them. Our rev A box tended to blow up.


Some small planes have full-plane parachutes. They land hard but
survivably.
Engine on fire, we circled and dumped fuel, then landed safely on one e> >ngine.

Planes can fly on one engine, as long as the failed one doesn\'t toss
blades and tear a wing off or something like that. They have
\"containment\" that usually works. Engines are tested to destruction to
make sure the blades stay inside.
There is a series on German satellite TV about plane crashes that happene> >d and they go into all the details
and follow the guys evaluating what\'s left.. to find the cause.

\"Aircrash investigation\" I\'d guess, they are not bad but there\'s a few yout=
ube channels*
with actual pilots going through the accident reports, watching those make > >you realise
the TV shows are often far from accurate
No, not Aircrash investigation, forgot he name, German channel, think it was called \'Mayday\' or something?
Will let you know when I hit it again (hundreds of channels here)
*to mention a few, Mentour Pilot and blancolirio

There is a lot that can go wrong, often pilot error like the one I follow> >ed
last week that crashed in a field near Schiphol airport,
pilot had one engine throttled down.. (propeller 2 engine plane) without > >knowing it (he did it himself)
so when steering towards the runway the plane tilted one way and he lost =
control..

There was one similar in Nepal, probably caused by the first officer pullin> >g the wrong handle feathering the engines
instead of lowering the flaps, like because he would normally be flying in > >the left seat as a captain, but on this flight
he was an instructor so he was in the right seat...
Checklist are interesting too, I have a checklist for some thing I do,
I went through it and sure enough one day I found out I had missed something...

There was this airplane .. they went through the takeoff checklist but were interrupted
by a stewardess making an appointment for the evening with one of the pilots (voice recorder was recovered)
so they forgot to set the flaps for takeoff.
Hundreds died, crashed at the end of the runway, ball of fire (full of fuel).

You want a computer there saying: \"Hey dummy, set your flaps or I will do it for you !!\"
Procedure is: Nobody allowed in the cockpit during prepare for takeoff, but human relations...

if it\'s the one I\'m thinking about the plane does have an alarm for not being properly configured for takeoff
but there have been at least one crash or near where it didn\'t sound, possible because some pilots had a habit
of pulling the fuse for that alarm because it would trigger when taxiing a little to fast

 

[Fred Bloggs]

On Saturday, March 18, 2023 at 6:57:33 PM UTC-4, John Larkin wrote:

On Sat, 18 Mar 2023 15:23:20 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Saturday, March 18, 2023 at 1:48:27?PM UTC-4, John Larkin wrote:
On Sat, 18 Mar 2023 07:44:01 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Friday, March 17, 2023 at 11:21:37?AM UTC-4, John Larkin wrote:
I\'ve been asked to design an 8-channel dummy load board. It\'s not very
challenging but somebody\'s got to do it. It will be used to simulate
small loads like solenoids or relays or torque motors. It needs some
inductance too, because the drivers often PWM. Maybe 10 or so watts
per channel.

I could do this electronically, but it would a lot easier and more
rugged if I use wirewound resistors. I was thinking of making a
conductance DAC, namely resistors R 2R 4R etc switched in parallel
across the inputs with an SSR per resistor.

But there is a history of clever load banks. When I was an EE student
at Tulane, two semisters of Electrical Machinery (with lab) was
mandatory. It was a pain but I learned a lot. We had a big load bank
in the machinery lab, a string of giant series resistors with a
3-position knife switch at each node. That made me think about using
series-parallel combinations to hit some target value.

https://www.dropbox.com/s/x3e7xxi13n6wd1o/Load_Banks_1.jpg?raw=1

The upper pic is the ancient Tulane load bank as I remember it.

I was thinking about the lower circuit for my gadget. I could use
wirewould resistors and kink the leads to space them maybe 3/4 inch
above my PCB, in the air stream. The higher value resistors might be
2512 surface mounts.

I think there is a tool to bend and kink resistor leads. Or we could
send a bunch out to a service maybe.

It\'s called standoff lead forming. There are bunches different tools, but it looks like the handheld plier types are more universal. Low cost too.

https://forum.digikey.com/t/bending-and-forming-leads/8184

How is any of this a puzzle?
A good design is most always a puzzle, which makes design interesting.

One issue is, how much power can you dissipate in 4 square inches of
PC board with some given air flow? Big heat sink with mosfets? Small
CPU cooler? I\'m thinking of using axial-lead wirewound resistors
spaced off the board enough that the leads have enough thermal
resistance to not scorch the board when the resistor gets very hot.

Keep in mind people tend to lose respect for a product that smells like it\'s burning. You should be determining the threshold case temperature at which outgassing becomes noticeable, via olfactory sensing, and see if reducing temps by half, with proper derating for ambient, does anything for you.
Vitreous enameled resistors would be best for not outgassing. Silicone
or whatever would be worse.

Wirewound resistors tend to run at crazy temps, like 270C, at full
power. I wouldn\'t want to scorch the PCB.

There are some nice DPAK power resistors that could be clamp mounted
on heat sinks, which would provide a lot of surface area.

There are also TO-220 power resistors, which could be attached to heat
sinks with nuts and bolts.

Setting off smoke detectors would be the absolute worst.

 

[legg]

On Sat, 18 Mar 2023 08:11:29 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

On Sat, 18 Mar 2023 07:13:33 -0400, legg <legg@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 14:41:51 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Fri, 17 Mar 2023 17:14:59 -0400, legg <legg@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 08:21:23 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:


I\'ve been asked to design an 8-channel dummy load board. It\'s not very
challenging but somebody\'s got to do it. It will be used to simulate
small loads like solenoids or relays or torque motors. It needs some
inductance too, because the drivers often PWM. Maybe 10 or so watts
per channel.

I could do this electronically, but it would a lot easier and more
rugged if I use wirewound resistors. I was thinking of making a
conductance DAC, namely resistors R 2R 4R etc switched in parallel
across the inputs with an SSR per resistor.

But there is a history of clever load banks. When I was an EE student
at Tulane, two semisters of Electrical Machinery (with lab) was
mandatory. It was a pain but I learned a lot. We had a big load bank
in the machinery lab, a string of giant series resistors with a
3-position knife switch at each node. That made me think about using
series-parallel combinations to hit some target value.

https://www.dropbox.com/s/x3e7xxi13n6wd1o/Load_Banks_1.jpg?raw=1

The upper pic is the ancient Tulane load bank as I remember it.

I was thinking about the lower circuit for my gadget. I could use
wirewould resistors and kink the leads to space them maybe 3/4 inch
above my PCB, in the air stream. The higher value resistors might be
2512 surface mounts.

I think there is a tool to bend and kink resistor leads. Or we could
send a bunch out to a service maybe.




Active I=kV with a delay would give you an inductance.


A real inductor stores energy, which a synthesized inductor usually
doesn\'t.

Stored energy pumps current into flyback diodes or equivalent.


Does the driver really care?

It certainly might.


Where\'d the word \'dummy\' originate in the spec? If it reflects
the attitude of the buyer, I\'d say \'No Bid\'. I\'ve had it with
idiots like that.

Oh, they are just a biggish aerospace company.

No bid? Is that a good business model?


RL

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


The minute you considered variable, multicase and
especially inductive, it ceased to be idiot-proof.

Use sockets and real loads, if it\'s that important.

RL

The customer has an existing design where they select and solder a
selected set of resistors and inductors per channel, unique to each
unit. We don\'t want to be in the business of doing that for them, with
every unit having its own dash number and BOM and test limits.

I\'d like to design a programmable dummy load board that we can
manufacture and stock and ship when we get an order.

It\'s looking like a straight conductance DAC is the way to go:
parallel N resistors (R, 2R, etc) with a solid-state switch per. Given
a binary control code K, net conductance is proportional to K so
resistance goes as 1/K. N=5 maybe; we\'re not simulating RTDs. That\'s
nice and simple and adds an open-circuit case for free. Two more SSRs
can add short and ground fault cases, selling points.

I like to add little goodies to products when it\'s not hard and
doesn\'t interfere with the base function. You never know if something
will appeal to someone and tip a basically emotional buy decision, as
in \"That thingie might be useful some day, let\'s buy theirs.\"

Colors matter too.

Overv time you\'ve talked about all sorts of low voltage loads
that swotted the heat in mosfets and a heatsink.

Doesn\'t that have a placxe here?

RL

 

[John Larkin]

On Sun, 19 Mar 2023 07:00:19 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On a sunny day (Sat, 18 Mar 2023 13:38:44 -0700 (PDT)) it happened Lasse
Langwadt Christensen <langwadt@fonz.dk> wrote in
9628b72f-aa02-40d2-b1e4-c5087e2c7083n@googlegroups.com>:

lørdag den 18. marts 2023 kl. 20.30.07 UTC+1 skrev Jan Panteltje:
On a sunny day (Sat, 18 Mar 2023 10:28:46 -0700) it happened John Larkin=

jla...@highlandSNIPMEtechnology.com> wrote in
kisb1ipbum7dulpqh...@4ax.com>:
On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <al...@comet.invalid
wrote:
I have no idea what a FADEC is or what its internals are
so I looked it up:
https://en.wikipedia.org/wiki/FADEC

Now I will stop flying!!!!

Each FADEC is redundant, and gets power from both the airframe DC
supply and from a dual alternator on its engine. Thet are very
reliable. Most engine problems are mechanical or fuel related. Birds
are bad in jet engines.

We sell alternator simulators that are used to test FADECs, which
furtunately people buy two at a time. It\'s kind of interesting, since
a PM alternator is basically a current source and the FADECs regulate
by shorting them. Our rev A box tended to blow up.


Some small planes have full-plane parachutes. They land hard but
survivably.
Engine on fire, we circled and dumped fuel, then landed safely on one e=
ngine.

Planes can fly on one engine, as long as the failed one doesn\'t toss
blades and tear a wing off or something like that. They have
\"containment\" that usually works. Engines are tested to destruction to=

make sure the blades stay inside.
There is a series on German satellite TV about plane crashes that happene=
d and they go into all the details
and follow the guys evaluating what\'s left.. to find the cause.

\"Aircrash investigation\" I\'d guess, they are not bad but there\'s a few yout=
ube channels*
with actual pilots going through the accident reports, watching those make =
you realise
the TV shows are often far from accurate

No, not Aircrash investigation, forgot he name, German channel, think it was called \'Mayday\' or something?
Will let you know when I hit it again (hundreds of channels here)


*to mention a few, Mentour Pilot and blancolirio

There is a lot that can go wrong, often pilot error like the one I follow=
ed
last week that crashed in a field near Schiphol airport,
pilot had one engine throttled down.. (propeller 2 engine plane) without =
knowing it (he did it himself)
so when steering towards the runway the plane tilted one way and he lost =
control..

There was one similar in Nepal, probably caused by the first officer pullin=
g the wrong handle feathering the engines
instead of lowering the flaps, like because he would normally be flying in =
the left seat as a captain, but on this flight
he was an instructor so he was in the right seat...

Checklist are interesting too, I have a checklist for some thing I do,
I went through it and sure enough one day I found out I had missed something...

We have a PCB release checklist. It\'s several pages.

 

[John Larkin]

On Sun, 19 Mar 2023 09:55:06 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Mar 2023 08:11:29 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Sat, 18 Mar 2023 07:13:33 -0400, legg <legg@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 14:41:51 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Fri, 17 Mar 2023 17:14:59 -0400, legg <legg@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 08:21:23 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:


I\'ve been asked to design an 8-channel dummy load board. It\'s not very
challenging but somebody\'s got to do it. It will be used to simulate
small loads like solenoids or relays or torque motors. It needs some
inductance too, because the drivers often PWM. Maybe 10 or so watts
per channel.

I could do this electronically, but it would a lot easier and more
rugged if I use wirewound resistors. I was thinking of making a
conductance DAC, namely resistors R 2R 4R etc switched in parallel
across the inputs with an SSR per resistor.

But there is a history of clever load banks. When I was an EE student
at Tulane, two semisters of Electrical Machinery (with lab) was
mandatory. It was a pain but I learned a lot. We had a big load bank
in the machinery lab, a string of giant series resistors with a
3-position knife switch at each node. That made me think about using
series-parallel combinations to hit some target value.

https://www.dropbox.com/s/x3e7xxi13n6wd1o/Load_Banks_1.jpg?raw=1

The upper pic is the ancient Tulane load bank as I remember it.

I was thinking about the lower circuit for my gadget. I could use
wirewould resistors and kink the leads to space them maybe 3/4 inch
above my PCB, in the air stream. The higher value resistors might be
2512 surface mounts.

I think there is a tool to bend and kink resistor leads. Or we could
send a bunch out to a service maybe.




Active I=kV with a delay would give you an inductance.


A real inductor stores energy, which a synthesized inductor usually
doesn\'t.

Stored energy pumps current into flyback diodes or equivalent.


Does the driver really care?

It certainly might.


Where\'d the word \'dummy\' originate in the spec? If it reflects
the attitude of the buyer, I\'d say \'No Bid\'. I\'ve had it with
idiots like that.

Oh, they are just a biggish aerospace company.

No bid? Is that a good business model?


RL

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


The minute you considered variable, multicase and
especially inductive, it ceased to be idiot-proof.

Use sockets and real loads, if it\'s that important.

RL

The customer has an existing design where they select and solder a
selected set of resistors and inductors per channel, unique to each
unit. We don\'t want to be in the business of doing that for them, with
every unit having its own dash number and BOM and test limits.

I\'d like to design a programmable dummy load board that we can
manufacture and stock and ship when we get an order.

It\'s looking like a straight conductance DAC is the way to go:
parallel N resistors (R, 2R, etc) with a solid-state switch per. Given
a binary control code K, net conductance is proportional to K so
resistance goes as 1/K. N=5 maybe; we\'re not simulating RTDs. That\'s
nice and simple and adds an open-circuit case for free. Two more SSRs
can add short and ground fault cases, selling points.

I like to add little goodies to products when it\'s not hard and
doesn\'t interfere with the base function. You never know if something
will appeal to someone and tip a basically emotional buy decision, as
in \"That thingie might be useful some day, let\'s buy theirs.\"

Colors matter too.


Overv time you\'ve talked about all sorts of low voltage loads
that swotted the heat in mosfets and a heatsink.

Doesn\'t that have a placxe here?

RL

I\'m planning a separate big single-channel electronic load board that
uses mosfets on a CPU cooler and can do programmed constant-current
and constant-resistance ac or dc over a huge range. That topology
would be complex for a small 8-channel load that has onboard
inductors. The mosfet thing needs isolated fast DACs and ADCs per
channel and closed loop control in an FPGA. Resistors and SSR are
sure easy.

A CPU cooler is a possibility on the 8-channel board. A K199 type
would fit on my board and can easily dissipate 150 watts. The bottom
copper plate would need to be tapped to screw down a bunch of
(expensive, unavailable) TO-220 resistors or something.

High thermal conductivity (ie, fairly pure) copper is gummy and a
nuisance to tap, but it can be done. That would roughly double the
cost of the cooler. At least TO-220 resistors don\'t need insulators
like mosfets would.

 

[John Larkin]

On Sat, 18 Mar 2023 10:54:12 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Saturday, March 18, 2023 at 8:20:02?AM UTC-7, John Larkin wrote:
On Sat, 18 Mar 2023 07:08:29 -0400, legg <le...@nospam.magma.ca> wrote:

A dummy load is usually invariable and requires no
operator adjustment.
Why? A programmable dummy load can be very useful.

A \'dummy\' can screw up even simple switches or rheostats.

They could wire anything wrong.

Yeah, and... for an inspection-quality load, you might want a barcode
for each of a dozen variants. At inspection time, if the right barcode isn\'t
scanned, the inspection is invalid.

If I suggest a product with even three variants my boss will attack
me. Production hates that. Hence programmability. Customers would like
programmability too.

Adjustable boxes aren\'t good \"standard\" loads for a formal inspection process, IMHO.
At a minimum, you\'d want a calibration date, and complete record of the settings, printed onto an
attachable sticker label, for the final report.

How does one calibrate eight different adjustable loads, each having dozens of settings?

I wouldn\'t calibrate the resistors; just specify their tolerance. We
would calibrate the ADCs, one per channel to report actual voltage and
current.

I don\'t think that something like 5% tolerance would be a problem for
people simulating solenoids or motors. The measurements could be
calibrated to 1%.

There are some very cool 2 and 3-channel isolated ADCs intended for
use in electric meters. Cheap but not super fast; good for average
measurements but not for closing fast control loops.

 

[John Larkin]

On Sun, 19 Mar 2023 05:49:06 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Saturday, March 18, 2023 at 6:57:33?PM UTC-4, John Larkin wrote:
On Sat, 18 Mar 2023 15:23:20 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Saturday, March 18, 2023 at 1:48:27?PM UTC-4, John Larkin wrote:
On Sat, 18 Mar 2023 07:44:01 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Friday, March 17, 2023 at 11:21:37?AM UTC-4, John Larkin wrote:
I\'ve been asked to design an 8-channel dummy load board. It\'s not very
challenging but somebody\'s got to do it. It will be used to simulate
small loads like solenoids or relays or torque motors. It needs some
inductance too, because the drivers often PWM. Maybe 10 or so watts
per channel.

I could do this electronically, but it would a lot easier and more
rugged if I use wirewound resistors. I was thinking of making a
conductance DAC, namely resistors R 2R 4R etc switched in parallel
across the inputs with an SSR per resistor.

But there is a history of clever load banks. When I was an EE student
at Tulane, two semisters of Electrical Machinery (with lab) was
mandatory. It was a pain but I learned a lot. We had a big load bank
in the machinery lab, a string of giant series resistors with a
3-position knife switch at each node. That made me think about using
series-parallel combinations to hit some target value.

https://www.dropbox.com/s/x3e7xxi13n6wd1o/Load_Banks_1.jpg?raw=1

The upper pic is the ancient Tulane load bank as I remember it.

I was thinking about the lower circuit for my gadget. I could use
wirewould resistors and kink the leads to space them maybe 3/4 inch
above my PCB, in the air stream. The higher value resistors might be
2512 surface mounts.

I think there is a tool to bend and kink resistor leads. Or we could
send a bunch out to a service maybe.

It\'s called standoff lead forming. There are bunches different tools, but it looks like the handheld plier types are more universal. Low cost too.

https://forum.digikey.com/t/bending-and-forming-leads/8184

How is any of this a puzzle?
A good design is most always a puzzle, which makes design interesting.

One issue is, how much power can you dissipate in 4 square inches of
PC board with some given air flow? Big heat sink with mosfets? Small
CPU cooler? I\'m thinking of using axial-lead wirewound resistors
spaced off the board enough that the leads have enough thermal
resistance to not scorch the board when the resistor gets very hot.

Keep in mind people tend to lose respect for a product that smells like it\'s burning. You should be determining the threshold case temperature at which outgassing becomes noticeable, via olfactory sensing, and see if reducing temps by half, with proper derating for ambient, does anything for you.
Vitreous enameled resistors would be best for not outgassing. Silicone
or whatever would be worse.

Wirewound resistors tend to run at crazy temps, like 270C, at full
power. I wouldn\'t want to scorch the PCB.

There are some nice DPAK power resistors that could be clamp mounted
on heat sinks, which would provide a lot of surface area.

There are also TO-220 power resistors, which could be attached to heat
sinks with nuts and bolts.

Setting off smoke detectors would be the absolute worst.

I plan to digitize actual load voltage and current on every channel.
An FPGA can calculate power dissipation and protect the parts. A
polyfuse might be prudent too.

 

[piglet]

On 17/03/2023 17:22, John Larkin wrote:

I was wondering if anyone had cute ideas. I considered PWM-ing a big
resistor, but that has complications.

Aha, yes I recall offering you that for a similar task in Aug 2016

piglet

 

[piglet]

On 19/03/2023 15:24, John Larkin wrote:

There are some very cool 2 and 3-channel isolated ADCs intended for
use in electric meters. Cheap but not super fast; good for average
measurements but not for closing fast control loops.

So use the cool ADCs for metrology and do the control loop with op-amp?

piglet

 

[Lasse Langwadt Christensen]

søndag den 19. marts 2023 kl. 16.13.07 UTC+1 skrev John Larkin:

On Sun, 19 Mar 2023 09:55:06 -0400, legg <le...@nospam.magma.ca> wrote:

On Sat, 18 Mar 2023 08:11:29 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:

On Sat, 18 Mar 2023 07:13:33 -0400, legg <le...@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 14:41:51 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:

On Fri, 17 Mar 2023 17:14:59 -0400, legg <le...@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 08:21:23 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:


I\'ve been asked to design an 8-channel dummy load board. It\'s not very
challenging but somebody\'s got to do it. It will be used to simulate
small loads like solenoids or relays or torque motors. It needs some
inductance too, because the drivers often PWM. Maybe 10 or so watts
per channel.

I could do this electronically, but it would a lot easier and more
rugged if I use wirewound resistors. I was thinking of making a
conductance DAC, namely resistors R 2R 4R etc switched in parallel
across the inputs with an SSR per resistor.

But there is a history of clever load banks. When I was an EE student
at Tulane, two semisters of Electrical Machinery (with lab) was
mandatory. It was a pain but I learned a lot. We had a big load bank
in the machinery lab, a string of giant series resistors with a
3-position knife switch at each node. That made me think about using
series-parallel combinations to hit some target value.

https://www.dropbox.com/s/x3e7xxi13n6wd1o/Load_Banks_1.jpg?raw=1

The upper pic is the ancient Tulane load bank as I remember it.

I was thinking about the lower circuit for my gadget. I could use
wirewould resistors and kink the leads to space them maybe 3/4 inch
above my PCB, in the air stream. The higher value resistors might be
2512 surface mounts.

I think there is a tool to bend and kink resistor leads. Or we could
send a bunch out to a service maybe.




Active I=kV with a delay would give you an inductance.


A real inductor stores energy, which a synthesized inductor usually
doesn\'t.

Stored energy pumps current into flyback diodes or equivalent.


Does the driver really care?

It certainly might.


Where\'d the word \'dummy\' originate in the spec? If it reflects
the attitude of the buyer, I\'d say \'No Bid\'. I\'ve had it with
idiots like that.

Oh, they are just a biggish aerospace company.

No bid? Is that a good business model?


RL

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


The minute you considered variable, multicase and
especially inductive, it ceased to be idiot-proof.

Use sockets and real loads, if it\'s that important.

RL

The customer has an existing design where they select and solder a
selected set of resistors and inductors per channel, unique to each
unit. We don\'t want to be in the business of doing that for them, with
every unit having its own dash number and BOM and test limits.

I\'d like to design a programmable dummy load board that we can
manufacture and stock and ship when we get an order.

It\'s looking like a straight conductance DAC is the way to go:
parallel N resistors (R, 2R, etc) with a solid-state switch per. Given
a binary control code K, net conductance is proportional to K so
resistance goes as 1/K. N=5 maybe; we\'re not simulating RTDs. That\'s
nice and simple and adds an open-circuit case for free. Two more SSRs
can add short and ground fault cases, selling points.

I like to add little goodies to products when it\'s not hard and
doesn\'t interfere with the base function. You never know if something
will appeal to someone and tip a basically emotional buy decision, as
in \"That thingie might be useful some day, let\'s buy theirs.\"

Colors matter too.


Overv time you\'ve talked about all sorts of low voltage loads
that swotted the heat in mosfets and a heatsink.

Doesn\'t that have a placxe here?

RL
I\'m planning a separate big single-channel electronic load board that
uses mosfets on a CPU cooler and can do programmed constant-current
and constant-resistance ac or dc over a huge range. That topology
would be complex for a small 8-channel load that has onboard
inductors. The mosfet thing needs isolated fast DACs and ADCs per
channel and closed loop control in an FPGA. Resistors and SSR are
sure easy.

A CPU cooler is a possibility on the 8-channel board. A K199 type
would fit on my board and can easily dissipate 150 watts. The bottom
copper plate would need to be tapped to screw down a bunch of
(expensive, unavailable) TO-220 resistors or something.

High thermal conductivity (ie, fairly pure) copper is gummy and a
nuisance to tap, but it can be done. That would roughly double the
cost of the cooler. At least TO-220 resistors don\'t need insulators
like mosfets would.

how much inductance do you need? that could take up quite a bit of space too

 

[John Larkin]

On Sun, 19 Mar 2023 17:24:32 +0000, piglet <erichpwagner@hotmail.com>
wrote:

On 17/03/2023 17:22, John Larkin wrote:

I was wondering if anyone had cute ideas. I considered PWM-ing a big
resistor, but that has complications.


Aha, yes I recall offering you that for a similar task in Aug 2016

piglet

If a customer might PWM his driver, with maybe flyback diodes or
mosfet avalanche or something, the best dummy load is a resistor in
series with an inductor. If he PWMs and we PWM it gets hard to think
about.

PWMing a resistor is fine for DC loads.

 

[John Larkin]

On Sun, 19 Mar 2023 10:39:00 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

søndag den 19. marts 2023 kl. 16.13.07 UTC+1 skrev John Larkin:
On Sun, 19 Mar 2023 09:55:06 -0400, legg <le...@nospam.magma.ca> wrote:

On Sat, 18 Mar 2023 08:11:29 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:

On Sat, 18 Mar 2023 07:13:33 -0400, legg <le...@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 14:41:51 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:

On Fri, 17 Mar 2023 17:14:59 -0400, legg <le...@nospam.magma.ca> wrote:

On Fri, 17 Mar 2023 08:21:23 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:


I\'ve been asked to design an 8-channel dummy load board. It\'s not very
challenging but somebody\'s got to do it. It will be used to simulate
small loads like solenoids or relays or torque motors. It needs some
inductance too, because the drivers often PWM. Maybe 10 or so watts
per channel.

I could do this electronically, but it would a lot easier and more
rugged if I use wirewound resistors. I was thinking of making a
conductance DAC, namely resistors R 2R 4R etc switched in parallel
across the inputs with an SSR per resistor.

But there is a history of clever load banks. When I was an EE student
at Tulane, two semisters of Electrical Machinery (with lab) was
mandatory. It was a pain but I learned a lot. We had a big load bank
in the machinery lab, a string of giant series resistors with a
3-position knife switch at each node. That made me think about using
series-parallel combinations to hit some target value.

https://www.dropbox.com/s/x3e7xxi13n6wd1o/Load_Banks_1.jpg?raw=1

The upper pic is the ancient Tulane load bank as I remember it.

I was thinking about the lower circuit for my gadget. I could use
wirewould resistors and kink the leads to space them maybe 3/4 inch
above my PCB, in the air stream. The higher value resistors might be
2512 surface mounts.

I think there is a tool to bend and kink resistor leads. Or we could
send a bunch out to a service maybe.




Active I=kV with a delay would give you an inductance.


A real inductor stores energy, which a synthesized inductor usually
doesn\'t.

Stored energy pumps current into flyback diodes or equivalent.


Does the driver really care?

It certainly might.


Where\'d the word \'dummy\' originate in the spec? If it reflects
the attitude of the buyer, I\'d say \'No Bid\'. I\'ve had it with
idiots like that.

Oh, they are just a biggish aerospace company.

No bid? Is that a good business model?


RL

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


The minute you considered variable, multicase and
especially inductive, it ceased to be idiot-proof.

Use sockets and real loads, if it\'s that important.

RL

The customer has an existing design where they select and solder a
selected set of resistors and inductors per channel, unique to each
unit. We don\'t want to be in the business of doing that for them, with
every unit having its own dash number and BOM and test limits.

I\'d like to design a programmable dummy load board that we can
manufacture and stock and ship when we get an order.

It\'s looking like a straight conductance DAC is the way to go:
parallel N resistors (R, 2R, etc) with a solid-state switch per. Given
a binary control code K, net conductance is proportional to K so
resistance goes as 1/K. N=5 maybe; we\'re not simulating RTDs. That\'s
nice and simple and adds an open-circuit case for free. Two more SSRs
can add short and ground fault cases, selling points.

I like to add little goodies to products when it\'s not hard and
doesn\'t interfere with the base function. You never know if something
will appeal to someone and tip a basically emotional buy decision, as
in \"That thingie might be useful some day, let\'s buy theirs.\"

Colors matter too.


Overv time you\'ve talked about all sorts of low voltage loads
that swotted the heat in mosfets and a heatsink.

Doesn\'t that have a placxe here?

RL
I\'m planning a separate big single-channel electronic load board that
uses mosfets on a CPU cooler and can do programmed constant-current
and constant-resistance ac or dc over a huge range. That topology
would be complex for a small 8-channel load that has onboard
inductors. The mosfet thing needs isolated fast DACs and ADCs per
channel and closed loop control in an FPGA. Resistors and SSR are
sure easy.

A CPU cooler is a possibility on the 8-channel board. A K199 type
would fit on my board and can easily dissipate 150 watts. The bottom
copper plate would need to be tapped to screw down a bunch of
(expensive, unavailable) TO-220 resistors or something.

High thermal conductivity (ie, fairly pure) copper is gummy and a
nuisance to tap, but it can be done. That would roughly double the
cost of the cooler. At least TO-220 resistors don\'t need insulators
like mosfets would.

how much inductance do you need? that could take up quite a bit of space too

I\'m estimating that 5 or 10 mH would keep their PWM driver happy. A
real solenoid or torque motor could be henries. In that case, they\'d
have to add it externally.

 

[John Larkin]

On Sun, 19 Mar 2023 17:28:35 +0000, piglet <erichpwagner@hotmail.com>
wrote:

On 19/03/2023 15:24, John Larkin wrote:

There are some very cool 2 and 3-channel isolated ADCs intended for
use in electric meters. Cheap but not super fast; good for average
measurements but not for closing fast control loops.


So use the cool ADCs for metrology and do the control loop with op-amp?

piglet

Simulating a resistor needs multiplication. That could be done with an
MDAC but gets complicated.

 

[piglet]

On 19/03/2023 18:29, John Larkin wrote:

On Sun, 19 Mar 2023 17:28:35 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 19/03/2023 15:24, John Larkin wrote:

There are some very cool 2 and 3-channel isolated ADCs intended for
use in electric meters. Cheap but not super fast; good for average
measurements but not for closing fast control loops.


So use the cool ADCs for metrology and do the control loop with op-amp?

piglet



Simulating a resistor needs multiplication. That could be done with an
MDAC but gets complicated.

Digital pot or PWM multiplier could do I guess, I have never used FPGAs
so still go first to analog ways!

piglet

 

[John Larkin]

On Sun, 19 Mar 2023 19:22:18 +0000, piglet <erichpwagner@hotmail.com>
wrote:

On 19/03/2023 18:29, John Larkin wrote:
On Sun, 19 Mar 2023 17:28:35 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 19/03/2023 15:24, John Larkin wrote:

There are some very cool 2 and 3-channel isolated ADCs intended for
use in electric meters. Cheap but not super fast; good for average
measurements but not for closing fast control loops.


So use the cool ADCs for metrology and do the control loop with op-amp?

piglet



Simulating a resistor needs multiplication. That could be done with an
MDAC but gets complicated.


Digital pot or PWM multiplier could do I guess, I have never used FPGAs
so still go first to analog ways!

piglet

A dpot could do the multiply well enough, at least over a moderate
signal range. A dpot as the actual load resistor wouldn\'t work well.

FPGAs are liberating in that you can do very complex signal processing
and control loops basically for free. As long as you get someone else
to grunt out the code.

 

[Jasen Betts]

On 2023-03-19, John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:

On Sun, 19 Mar 2023 17:28:35 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 19/03/2023 15:24, John Larkin wrote:

There are some very cool 2 and 3-channel isolated ADCs intended for
use in electric meters. Cheap but not super fast; good for average
measurements but not for closing fast control loops.


So use the cool ADCs for metrology and do the control loop with op-amp?

piglet



Simulating a resistor needs multiplication. That could be done with an
MDAC but gets complicated.

Could be done with a digital pot, ah yeah, that\'s a type of MDAC I
guess.

--
Jasen.
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