Handling S╫!┬Ty Celebrity
Added 2022-11-28 22:48:43 +0000 UTCSo you wanna be a Rock 'n Roll Star? Well, listen now - hear what I say....
Comments
I sure understand the time constraint problem. I had to "bite the bullet" and procure the over-complicated 400Hz aircraft inverters just so I could move on to wiring all of the 400Hz aircraft stuff. Thanks for your suggestions. I can see they have a feedback circuit in the aircraft inverters probably doing exactly what you described.
Matt Wietlispach
2022-12-14 02:10:32 +0000 UTCPutting out a clean 1kW 400Hz sine wave into a step-up transformer is much easier than making a 1kW audio amp good to 22kHz. Things that are hard at higher audio frequencies are downright simple at 400Hz. All my homemade lab supplies are DC to 1kHz output, bipolar (sink/source). The load sense pins can be fed from a transformer output, with a local feedback for higher frequencies. Actually, now that this discussion came up, I might add the transformer feedback compensation network and divider into the box so it could be used for making 100-300V output (not at 1kW though, those are 200W supplies). One fine day I’ll have to publish those but I’ve barely got enough time to use them :)
Kuba Sunderland-Ober
2022-12-13 21:56:21 +0000 UTCYou said it very well; it's the same reason the switch mode power supplies are so small (per watt) compared to the old classic 50/60Hz transformer PSUs. A switch mode power supply runs on tens or hundreds of kilohertz - requiring thousands less impedance and inductance of the windings. And since inductance is directly proportional to the number of turns, plus the core material (ferrite rather than iron alloy) has better magnetic permeability and even less turns can be used... Using 50 rather than 1000 turns is a huge difference in weight, size and cost. That's why.
Keri Szafir
2022-12-10 19:31:54 +0000 UTCI dont know how Fred Rogers would fare today, but I do know that he once sued the KKK because of stuff they had done to him. https://www.snopes.com/fact-check/mister-rogers-sue-kkk/ He was a Man that was not afraid.
SingularCurve
2022-12-02 22:40:37 +0000 UTCI have heard of this type of home-brew 3 Phase 115V 400Hz power many times before. I have no doubt someone could create this from scratch. The only two I ever saw working were single phase and they were unstable and used oversized heat sinks and the lack of proper transformers/inductors resulting in distorted sine waves. It's not enough to generate the three phase power, the 400Hz sensors depend on a single reference between transmitter and receiver on just one of the 3 phase legs. The power has to be stable when new loads are added or removed from each, or all, phases. Different loads will apply to each of the 3 phase legs if you're using real avionics. The power supply has to contend with keeping everything in phase while experiencing different loads on each of the three phase outputs. I am confident that you could build this power supply. Many of Fran's patrons could. But a clean 10 amps of 115V 400Hz 3 Phase requires power semiconductors and inductors that can shape the signal into a clean sine wave. Taking apart the expensive airworthy 28VDC to 115V 400Hz inverters, depending on age, reveals more efficient power semiconductors run by a simple oscillator that switches power to the input of a custom center tap transformer. The older they are, the noisier they are. The transformers buzz terribly when the switching transistors are pulsing their inputs. I have never seen, at any price, an inverter that uses power semiconductors only. Every inverter I've seen are very easy to reverse-engineer, but every one of them had custom inductors/transformer(s). Even old, used avionics are still expensive. For me, I am not willing to power such expensive instrumentation and related equipment from a power supply not over-engineered and proven reliable enough to be airworthy. The truth is, no matter what home-brew power supply I would build from scratch, I would be very hesitant to trust expensive equipment on whatever large power supply I made. That's MY limitation. I don't design high capacity power supplies for critical equipment. The build/buy decision always leads to a used inverter. I totally admit my lack of experience in designing and building high capacity AC power supplies. I need to concentrate on a great many other electronic interfaces and need to know I have a source of clean power that won't damage expensive avionics. I need that as a "given". I've never seen anyone successfully build a 10 amp 115V 3 Phase 400Hz power supply from commonly available components. But I know many Fran patrons could. But I truly do think a stable output at that amperage, with a clean sine wave and 3 phase on top of that, is in no way "easy" or worth the R&D time,
Matt Wietlispach
2022-11-30 23:45:05 +0000 UTCI don’t get people’s trepidation with 400Hz. It is easy to generate using stuff you’d find in many thrift stores. One audio amp output channel plus a suitable mains transformer at the output per phase. Making the 400Hz three phase reference takes an Arduino or a 555-based oscillator, a Johnson counter, and a couple gates. Almost more work to write about it than making it work. But then you need to know something to see that it’s easy… Knowledge used to be harder to find in the 90s. Now it’s abundant but filtering the nonsense out seems like a full time job sometimes… I’m in full agreement about letting people do their thing without pestering them, celebrity or no celebrity.
Kuba Sunderland-Ober
2022-11-30 22:17:41 +0000 UTCThe answer to why commercial/military aircraft use 3 Phase 400Hz power systems comes down to the #1 concern of all aircraft manufacturers: weight. Everything that is inductive, starting with the generators on the engines, to every transformer, AC relay coil, AC motor, fluorescent light ballast, sensors such a synchros, and so much more have to be as small, light and efficient as possible. I’m not an expert in electrical frequency properties as it applies to transformer core saturation and all the physics behind it. But it’s very straight-forward in its advantages. A 115V 50/60Hz transformer delivering 10 amps of 28VAC on the output is going to be one very large and heavy transformer. Generators mounted on jet engines would also be at least 2 to 4 times larger and heavier. An equivalent 115V 400Hz generator system and 28VAC transformer will easily be less than half the size/weight of the 50/60Hz versions. Also, having the electrical system running on 3 phase generators also dramatically reduces the size of devices like electric motors. For instance, the small motors fitted into the cockpit crew seats, to enable electrical adjustment of all the seat positioning, are 115V 400Hz 3 phase. This makes them very powerful in a very small package. You may be asking why your car has electrical seat adjustments that run from 12VDC motors with no problems. It’s different on aircraft crew seats because their structure is so much heavier than an automobile seat and the AC motors are brushless, thus eliminating wear. And as each pilot has his/her own seat position preferences, the motors are used quite often as crew changes probably happen multiple times every day. The motors have to be powerful, light and reliable. Everything that uses inductive loads all benefit from 400Hz input power. In all AC-driven “black boxes” in the avionics bay have internal power supplies that are tiny compared to 50/60Hz equivalents. If they use a step-down transformer as the first thing being fed by external 115V 400Hz, they can be smaller and in many cases generate less heat. Regardless, the “black boxes” in the avionics bay are mounted to mating trays which are in turn mounted to a shelf that has round holes everywhere that help distribute cooling air through the shelves, up the hollow center trays and directly into the air inputs at the bottom of the black boxes. There is a large 3 Phase 400Hz blower that forces air through the avionics bay equipment racks that is also tiny in comparison to a 50/60Hz version. That cooling air flow is essential and the crew is warned immediately if there is a fault in the avionics cooling system. Aside from the electric motors that move everything from crew seats to emergency backup landing gear motors, there are some other consumers of 3 Phase 115V 400Hz power such as HF radios that suck up a ton of power when they transmit. If the radio ran on a single phase of 400Hz power, the cabling leading to the HF would be much thicker, thus adding more weight. Worse if it accepted 28 VDC at 75 amps. Position sensing variable transformers, AKA “synchros”, depend on 400Hz as power to keep them small. They accept 26VAC single phase in and provide 3 phase 11.5 VAC out which is connected to an indicator containing the same type of synchro with its shaft connected to a pointer. Turning the shaft on the synchro results in the 3 phase output changing and the shaft moving in concert with its transmitter. They make 60Hz versions of synchros any you can see right away how large the 60Hz versions are. There’s no way to fit them into a typical aircraft instrument. Weight is so important that remote control circuit breakers are used in a center accessory compartment between the wings. The thick generator output wiring leads to this electrical relay and circuit breaker compartment instead of all the way through the fuselage and into the cockpit circuit breaker panels. Again, saving weight is critically important and the fewer thick heavy load-carrying power cables, the better, What most people ask me when I tell them they “must” have 400 Hz power to drive avionics is “Why can’t I just send in 115V 50/60Hz?” Well, the 400Hz inductors will literally blow out their primary windings the second the 60Hz power is supplied. So, there is no realistic way around the 400Hz power problem unless you acquire a static inverter that translates 28VDC to 115VAC 400Hz. These are sometimes affordable on eBay. There are also “power converters” that can accept 60Hz in and output 400Hz power. Those are not only cost-prohibitive, but they weigh a ton. But you can use 60Hz transformers in a 400Hz system. No problems there except the output will probably not be a clean sine wave because the transformer was not designed to operate on 400Hz. So you won’t blow up a 60Hz transformer by applying 400Hz to its input windings, but you will DESTROY any 400Hz inductor you try to feed 60Hz into. This makes working with avionics very expensive, but it is entirely possible if you can afford a DC-AC inverter or a power converter. I could go on for pages, but I think this provides the basic “why” of 400Hz and how you cannot substitute 60Hz for 400Hz.
Matt Wietlispach
2022-11-30 21:47:56 +0000 UTCOK, I have to ask, what does 400 Hz mean to aerospace equipment and why did that change things? I know 400 Hz power is used in aircraft, but that's all I know.
Circuitmike
2022-11-30 19:42:20 +0000 UTCFran, I totally understand your situation. I used to have a website many years ago, before YouTube was even technically possible, and people would email me for aircraft instrument reverse-engineering advice, simulator setups with real parts, whatever. But for the few that seemed really interested, I devoted some real time to providing them with data and even free parts if I thought they were serious enough. Well, they all lost interest the second they understood what 400Hz meant to aerospace equipment and they quickly vanished and sold the stuff I gave them on eBay, which was a lot different back then. That tiny, minuscule, experience just made me kill the website and just stay underground with the handful of vetted fellow sim builders using real parts. Thin skin, I guess. Or common sense on how to spend my energy. I've never done anything close to what you have been doing on YouTube. Never will. If I saw you in a coffee shop, yes, I would introduce myself as a patron, but I wouldn't expect you to remember my name and I sure would respect your privacy and let you enjoy your breakfast without being badgered with questions. That's what these patron-only message streams are for. I've heard of a lot of celebrities who are truly awful to be around and are basically lashing out at everyone. But it's easy to sit on my ass and pass judgement. If I were in their shoes, with all the demands that fame brings with it, Including the seriously dangerous nutcases, I don't know how I would be. I think you're brave as hell to be as "public" as you are in light of the lunatic fringe that emails you with hate. As long they are the small minority, you can brush them off. I'm sure that some of their negative rants might actually be unintentionally funny. Usually people who hate really make themselves look completely stupid. Like in the pride parade you filmed, the tiniest of minorities held up signs using Jesus Christ as a focal point to hate everyone who was "different" than them. I personally don't think Jesus Christ would help them paint signs, pay their gas money and have them speak on his behalf to foster hate and fear. They just looked "stupid". But, you've known for a long long time that there are far more good people out there than the small percentage of turdswish spewing hate. Stay strong!
Matt Wietlispach
2022-11-29 04:23:31 +0000 UTC
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