On a sunny day (Sat, 18 Mar 2023 07:55:03 -0700) it happened John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote in <agjb1ih89jhol5ltl58m52cinf32eiij0t@4ax.com>:>On Sat, 18 Mar 2023 05:43:35 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Fri, 17 Mar 2023 10:22:33 -0700) it happened John Larkin >><jlarkin@highlandSNIPMEtechnology.com> wrote in >><5l791i1hev1qsuei98p7t83mprc4881jhk@4ax.com>: >> >>>On Fri, 17 Mar 2023 16:40:09 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote: >>> >>>>On a sunny day (Fri, 17 Mar 2023 08:21:23 -0700) it happened John Larkin >>>><jlarkin@highlandSNIPMEtechnology.com> wrote in >>>><u6091ide59fffa8gafp93ipmmejp424r5j@4ax.com>: >>>> >>>>> >>>>>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. >>>> >>>>Yes why not.. >>>>'SSR' == solid state rectifier ? you mean relay? You get AC as input right? >>>>oh wait you mean sold state relay.... >>> >>>Yes. >>> >>>>googling SSR gives among many things Wikipedia with "Soviet Socialist Republic" >>>> >>>> >>>>>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 >>>> >>>>We use rectangles as resistor symbol here :-) >>> >>>Quaint olde world customs. >>> >>>> >>>> >>>> >>>>>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. >>>> >>>>My setup: >>>> https://panteltje.nl/pub/power_resistors_IMG_6291.JPG >>>> uses test leads with alligator clips to switch configuration. >>> >>>We have a couple of Kikusui benchtop electronic load boxes, which are >>>handy. They can do square wave loads, handy for checking power supply >>>dynamics. >>> >>>I want programmable 0 to 1 zillon ohms, isolated, ac/dc, 10 or 20 >>>watts, metered, overload protected, 8 loads per board, maybe 4 square >>>inches per channel. >>> >>>I was wondering if anyone had cute ideas. I considered PWM-ing a big >>>resistor, but that has complications. >>> >>>> >>>>So as to Soviet Socialist Republic >>>>Here a very funny thing happened in politics >>>>We just had elections, and a new party, BBB (translated: farmers people movement) >>>>wiped out all parties going from zero to more than the biggest ones. >>>>Protest against all the CO2 idiots who want to close farms because cows make CO2. >>>>I voted for them too :-) >>>>We need farmers and their produce. >>> >>>Most people think eating is good. >>> >>>>We will see where it goes now... >>>> >>>> >>> >>>People will surely get tired of crazy prices and blackouts and food >>>shortages and waiting hours to recharge their cars. >> >>I did a switched inductor thing many many years ago, >>it was for tuning and used relays IIRC (up to a few hundred kHz). >>I see electronics to simulate inductors as a possibility. > >That's worth discussing, but I don't think it's practical in my case, >making small, fairly inexpensive dummy loads that can behave like >solenoids or relay coils. They need to behave when the user PWMs them >or whatever. > >>But what sort of users need this? >>Normally you would test on the real thing >>any unexpected things could exist in a real system, >>parasitic capacitances, lead resistance and inductances, >>unexpected couplings.. what not. >>Nothing like a real test. > >If one is testing FADECs, for example, it might be inconvenient to >have a jet engine as part of every test bench.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!!!! Carry a parachute ? Still be able to open doors? I once was on a flight from Barcelona Spain to Amsterdam, about 15 minutes after takeoff the 'hammer' came on 'Hammer' is the alarm bells in the cockpit. Engine on fire, we circled and dumped fuel, then landed safely on one engine. Those alarms came on just when I was reading about Bill Clignon and Monica... Before takeoff I did see a large pool of fluid under that engine thought 'will not be oil, somebody must have checked'. Captain just walked in without even a look. After I got back home later on an other flight I called the newspaper and they then did an article on airplane maintenance. Much later I worked at Schiphol airport in Amsterdam... design stuff. That was years after a 747 cargo plane flew into the flat next to were I lived 4 years earlier... Long before all that I was in the cockpit of a F100 super sabre at an airs how on a mil airport here.. Had not had any English yet, so that big red button with 'ARM' on it must be the start button so I pressed it, Alarm went of and they took me out of that cockpit. Our neighbor was a jet pilot, he had got me in.. was maybe 12 years old? Now when the flying cup and saucers land here OK.. top secret, will be silent now.. But all that one more reason to test on the real thing! I do see the convenience point too... You do not need a whole jet engine in the workshop, but the relevant relays and other things that FADEC drives should not be so hard to have around?>>Bridge rectifier with a power MOSFET in it for AC load? >>Gives all sort of problems too... >> > >A bridge ahead of some active load is an interesting idea, but it >doesn't look ohmic at low voltages and can't return energy like a real >inductor can. I have a mosfet-based load circuit that does look ohmic >for ac or dc, all the way through zero volts, but it still doesn't >store energy.It better be very good as lives depend on it (and you maybe be sued if you screw up). In broadcasting where I worked your job could depend on it worst case...
load bank puzzle
Started by ●March 17, 2023
Reply by ●March 18, 20232023-03-18
Reply by ●March 18, 20232023-03-18
On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Sat, 18 Mar 2023 07:55:03 -0700) it happened John Larkin ><jlarkin@highlandSNIPMEtechnology.com> wrote in ><agjb1ih89jhol5ltl58m52cinf32eiij0t@4ax.com>: > >>On Sat, 18 Mar 2023 05:43:35 GMT, Jan Panteltje <alien@comet.invalid> >>wrote: >> >>>On a sunny day (Fri, 17 Mar 2023 10:22:33 -0700) it happened John Larkin >>><jlarkin@highlandSNIPMEtechnology.com> wrote in >>><5l791i1hev1qsuei98p7t83mprc4881jhk@4ax.com>: >>> >>>>On Fri, 17 Mar 2023 16:40:09 GMT, Jan Panteltje <alien@comet.invalid> >>>>wrote: >>>> >>>>>On a sunny day (Fri, 17 Mar 2023 08:21:23 -0700) it happened John Larkin >>>>><jlarkin@highlandSNIPMEtechnology.com> wrote in >>>>><u6091ide59fffa8gafp93ipmmejp424r5j@4ax.com>: >>>>> >>>>>> >>>>>>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. >>>>> >>>>>Yes why not.. >>>>>'SSR' == solid state rectifier ? you mean relay? You get AC as input right? >>>>>oh wait you mean sold state relay.... >>>> >>>>Yes. >>>> >>>>>googling SSR gives among many things Wikipedia with "Soviet Socialist Republic" >>>>> >>>>> >>>>>>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 >>>>> >>>>>We use rectangles as resistor symbol here :-) >>>> >>>>Quaint olde world customs. >>>> >>>>> >>>>> >>>>> >>>>>>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. >>>>> >>>>>My setup: >>>>> https://panteltje.nl/pub/power_resistors_IMG_6291.JPG >>>>> uses test leads with alligator clips to switch configuration. >>>> >>>>We have a couple of Kikusui benchtop electronic load boxes, which are >>>>handy. They can do square wave loads, handy for checking power supply >>>>dynamics. >>>> >>>>I want programmable 0 to 1 zillon ohms, isolated, ac/dc, 10 or 20 >>>>watts, metered, overload protected, 8 loads per board, maybe 4 square >>>>inches per channel. >>>> >>>>I was wondering if anyone had cute ideas. I considered PWM-ing a big >>>>resistor, but that has complications. >>>> >>>>> >>>>>So as to Soviet Socialist Republic >>>>>Here a very funny thing happened in politics >>>>>We just had elections, and a new party, BBB (translated: farmers people movement) >>>>>wiped out all parties going from zero to more than the biggest ones. >>>>>Protest against all the CO2 idiots who want to close farms because cows make CO2. >>>>>I voted for them too :-) >>>>>We need farmers and their produce. >>>> >>>>Most people think eating is good. >>>> >>>>>We will see where it goes now... >>>>> >>>>> >>>> >>>>People will surely get tired of crazy prices and blackouts and food >>>>shortages and waiting hours to recharge their cars. >>> >>>I did a switched inductor thing many many years ago, >>>it was for tuning and used relays IIRC (up to a few hundred kHz). >>>I see electronics to simulate inductors as a possibility. >> >>That's worth discussing, but I don't think it's practical in my case, >>making small, fairly inexpensive dummy loads that can behave like >>solenoids or relay coils. They need to behave when the user PWMs them >>or whatever. >> >>>But what sort of users need this? >>>Normally you would test on the real thing >>>any unexpected things could exist in a real system, >>>parasitic capacitances, lead resistance and inductances, >>>unexpected couplings.. what not. >>>Nothing like a real test. >> >>If one is testing FADECs, for example, it might be inconvenient to >>have a jet engine as part of every test bench. > >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.>Carry a parachute ? Still be able to open doors? >I once was on a flight from Barcelona Spain to Amsterdam, >about 15 minutes after takeoff the 'hammer' came on >'Hammer' is the alarm bells in the cockpit. >Engine on fire, we circled and dumped fuel, then landed safely on one engine.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.>Those alarms came on just when I was reading about Bill Clignon and Monica... >Before takeoff I did see a large pool of fluid under that engine >thought 'will not be oil, somebody must have checked'. >Captain just walked in without even a look. >After I got back home later on an other flight I called the newspaper and they then did an article on airplane maintenance. >Much later I worked at Schiphol airport in Amsterdam... design stuff. >That was years after a 747 cargo plane flew into the flat next to were I lived 4 years earlier... >Long before all that I was in the cockpit of a F100 super sabre at an airs how on a mil airport here.. >Had not had any English yet, so that big red button with 'ARM' on it must be the start button >so I pressed it, Alarm went of and they took me out of that cockpit. >Our neighbor was a jet pilot, he had got me in.. was maybe 12 years old? >Now when the flying cup and saucers land here OK.. top secret, will be silent now.. > >But all that one more reason to test on the real thing! >I do see the convenience point too... >You do not need a whole jet engine in the workshop, but the relevant relays and other things that FADEC drives should not be so hard to have around? > > > >>>Bridge rectifier with a power MOSFET in it for AC load? >>>Gives all sort of problems too... >>> >> >>A bridge ahead of some active load is an interesting idea, but it >>doesn't look ohmic at low voltages and can't return energy like a real >>inductor can. I have a mosfet-based load circuit that does look ohmic >>for ac or dc, all the way through zero volts, but it still doesn't >>store energy. > >It better be very good as lives depend on it (and you maybe be sued if you screw up). >In broadcasting where I worked your job could depend on it worst case...
Reply by ●March 18, 20232023-03-18
lørdag den 18. marts 2023 kl. 18.28.59 UTC+1 skrev John Larkin:> On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <al...@comet.invalid> > wrote: > > >On a sunny day (Sat, 18 Mar 2023 07:55:03 -0700) it happened John Larkin > ><jla...@highlandSNIPMEtechnology.com> wrote in > ><agjb1ih89jhol5ltl...@4ax.com>: > > > >>On Sat, 18 Mar 2023 05:43:35 GMT, Jan Panteltje <al...@comet.invalid> > >>wrote: > >> > >>>On a sunny day (Fri, 17 Mar 2023 10:22:33 -0700) it happened John Larkin > >>><jla...@highlandSNIPMEtechnology.com> wrote in > >>><5l791i1hev1qsuei9...@4ax.com>: > >>> > >>>>On Fri, 17 Mar 2023 16:40:09 GMT, Jan Panteltje <al...@comet.invalid> > >>>>wrote: > >>>> > >>>>>On a sunny day (Fri, 17 Mar 2023 08:21:23 -0700) it happened John Larkin > >>>>><jla...@highlandSNIPMEtechnology.com> wrote in > >>>>><u6091ide59fffa8ga...@4ax.com>: > >>>>> > >>>>>> > >>>>>>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. > >>>>> > >>>>>Yes why not.. > >>>>>'SSR' == solid state rectifier ? you mean relay? You get AC as input right? > >>>>>oh wait you mean sold state relay.... > >>>> > >>>>Yes. > >>>> > >>>>>googling SSR gives among many things Wikipedia with "Soviet Socialist Republic" > >>>>> > >>>>> > >>>>>>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 > >>>>> > >>>>>We use rectangles as resistor symbol here :-) > >>>> > >>>>Quaint olde world customs. > >>>> > >>>>> > >>>>> > >>>>> > >>>>>>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. > >>>>> > >>>>>My setup: > >>>>> https://panteltje.nl/pub/power_resistors_IMG_6291.JPG > >>>>> uses test leads with alligator clips to switch configuration. > >>>> > >>>>We have a couple of Kikusui benchtop electronic load boxes, which are > >>>>handy. They can do square wave loads, handy for checking power supply > >>>>dynamics. > >>>> > >>>>I want programmable 0 to 1 zillon ohms, isolated, ac/dc, 10 or 20 > >>>>watts, metered, overload protected, 8 loads per board, maybe 4 square > >>>>inches per channel. > >>>> > >>>>I was wondering if anyone had cute ideas. I considered PWM-ing a big > >>>>resistor, but that has complications. > >>>> > >>>>> > >>>>>So as to Soviet Socialist Republic > >>>>>Here a very funny thing happened in politics > >>>>>We just had elections, and a new party, BBB (translated: farmers people movement) > >>>>>wiped out all parties going from zero to more than the biggest ones. > >>>>>Protest against all the CO2 idiots who want to close farms because cows make CO2. > >>>>>I voted for them too :-) > >>>>>We need farmers and their produce. > >>>> > >>>>Most people think eating is good. > >>>> > >>>>>We will see where it goes now... > >>>>> > >>>>> > >>>> > >>>>People will surely get tired of crazy prices and blackouts and food > >>>>shortages and waiting hours to recharge their cars. > >>> > >>>I did a switched inductor thing many many years ago, > >>>it was for tuning and used relays IIRC (up to a few hundred kHz). > >>>I see electronics to simulate inductors as a possibility. > >> > >>That's worth discussing, but I don't think it's practical in my case, > >>making small, fairly inexpensive dummy loads that can behave like > >>solenoids or relay coils. They need to behave when the user PWMs them > >>or whatever. > >> > >>>But what sort of users need this? > >>>Normally you would test on the real thing > >>>any unexpected things could exist in a real system, > >>>parasitic capacitances, lead resistance and inductances, > >>>unexpected couplings.. what not. > >>>Nothing like a real test. > >> > >>If one is testing FADECs, for example, it might be inconvenient to > >>have a jet engine as part of every test bench. > > > >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. > >Carry a parachute ? Still be able to open doors? > >I once was on a flight from Barcelona Spain to Amsterdam, > >about 15 minutes after takeoff the 'hammer' came on > >'Hammer' is the alarm bells in the cockpit. > >Engine on fire, we circled and dumped fuel, then landed safely on one engine. > 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.https://www.youtube.com/shorts/yIUzWPc7pqc
Reply by ●March 18, 20232023-03-18
On Sat, 18 Mar 2023 07:44:01 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.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.
Reply by ●March 18, 20232023-03-18
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. 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?
Reply by ●March 18, 20232023-03-18
On a sunny day (Sat, 18 Mar 2023 10:28:46 -0700) it happened John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote in <kisb1ipbum7dulpqhanh1l0m95l2hglius@4ax.com>:>On Sat, 18 Mar 2023 15:46:03 GMT, Jan Panteltje <alien@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 engine. > >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 happened and they go into all the details and follow the guys evaluating what's left.. to find the cause. I have seen maybe 10 or more plain crashes analyzed now, from the thing that got hit by birds and landed in the Hudson to the Concord etc etc Flight recorder voice playback, instruments status displayed, fault finding is an art. Very nice job they do, every single part is looked at and sometimes the whole plane reconstructed from fragments, engines taken apart, radar traces evaluated.. 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.. And communication between captain and co-pilot, co-pilot not daring to speak up to captain who takes wrong decisions, a LOT comes into play. Cockpit Resource Management flyaeroguard.com/blog/2020/08/10/what-is-crew-resource-management/ Human factor... Automation is not all that hard: https://panteltje.nl/panteltje/quadcopter/index.html but the more you automate the less pilots are used to flying themselves... Sure redundancy, but at high altitude high energy particles can mess up your FADECs. Then it becomes a matter of chance. OTOH if you consider my laptop is now 10 years old and still going strong, I also have a PC that is close to 20 years old now and still I use it sometimes.... I have a little 8052AH BASIC computer I build in the late eighties that still works: https://panteltje.nl/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside_img_1727.jpg even the nicads still work So automation better than a human flying? Maybe But look at Tesla and the accidents that happened? Interesting subject. I did some manual writing for stuff like that at Schiphol airport 'groot alarm vliegtuig' there are procedures in place if anything goes wrong at the airport also security related.. ...
Reply by ●March 18, 20232023-03-18
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 engine. > > > >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 happened 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 youtube channels* with actual pilots going through the accident reports, watching those make you realise the TV shows are often far from accurate *to mention a few, Mentour Pilot and blancolirio> 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...
Reply by ●March 18, 20232023-03-18
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.
Reply by ●March 18, 20232023-03-18
On Sat, 18 Mar 2023 15:23:20 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.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.
Reply by ●March 18, 20232023-03-18
lørdag den 18. marts 2023 kl. 23.57.33 UTC+1 skrev John Larkin:> 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.https://jlcpcb.com/help/newsdetail/62-JLCPCB-Direct-Heatsink-Copper-Cored-PCBs-Available-Now!
