Comments by "Paul Frederick" (@1pcfred) on "The Engineering Mindset" channel.

You really don't. It depends what AC motor how you control it. An induction AC motor you speed control by varying the current frequency. The device name is a Variable Frequency Drive (VFD). Universal brushed DC motor you vary the speed by chopping the current. Those are commonly called dimmer switches but a dimmer switch that can handle an inductive load has additional circuitry in it to deal with the back EMF. That's called a snubber network. It's basically a resistor and a capacitor.
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The controller accepts a PWM signal but the control is a sequencer. PWM is usually fixed frequency too. The width of the pulse just changes. This video really didn't explain how BLDC works internally too well. It glossed over that part. It didn't mention H bridges or dead time once.
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@TheManeliss the power to weight ratio of stepper motors isn't the best.
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@rongarza9488 you ever try to push a chain?
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@danielassayag1484 you're welcome.
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When that wire burned it was creating light then.
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Resistance impedes flow too.
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@TheManeliss stepper motors can be pretty powerful. I have one here that runs off line voltage. It's a NEMA 34 frame. It don't go fast at 60 Hz but you ain't stopping it.
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@TheManeliss I have and have used a lot of brush motors, if that's what you mean.
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@TheManeliss I have many brushed motors that have run for a long time with no trouble. I have had some that wore their brushes out fairly quickly though. So it seems like either the motor is good or it is not. Mostly in my experience they're good. Sometimes not so good. I've also seen brushed motors just burn up too. that's not so good. Then I do not think that is a quality issue but the motor was just pushed too hard. A brushed motor is very compact for the amount of power it outputs. But that small size can be a weakness. It is not hard for the poor little things to work to death.
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That's a separate topic.
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What voltage does to a coil of wire depends on the gauge of the wire and how many turns of wire are in the coil. Inductance is a difficult property to wrap one's head around. At least I've always found that to be the case. It took a while for humanity to understand it. So I'm not the only one.
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@pgmcr5413 that voltage changes the ADC value which the program uses to change the PWM signal. It's input.
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A bit yeah. But an ignition "coil" is really two coils. A car ignition coil is a step up transformer. The car's ignition system runs the coil on pulsed DC. So the primary is constantly being switched on and off. This video did not really touch on magnetic coupling of currents between conductors. But that's something else we do with inductors a lot.
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So why is the motor driver called the "speed controller" when the PWM signal is generated by something else which would more accurately be called the actual speed controller? I'd have been interested in learning about the sequencer in the driver. The device that takes the PWM input and outputs the 3 phase signals to the motor.
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Yes they do. Alternating current is a sinusoidal waveform. Here DC is just getting switched on and off. It's still DC.
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That would depend on if the feature exists in hardware. It should be possible. Whether it is implemented is another story. So I'd answer with a definite maybe.
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Permanent magnet magnet motors have induction but are not induction motors. The induction really isn't doing anything in a BLDC motor. Induction motors do not have permanent magnets and instead the current is induced from the stator to the rotor. It's kind of weird. Which is why it took a screwball like Tesla to dream it up. They couldn't make a BLDC motor in Tesla's time because they had no way of switching the current on and off like BLDC needs. I guess they could have if they really tried but it wouldn't have been practical to do with what they had to work with. BLDC didn't make sense until we had semiconductors that could switch high current at low resistance. That's why BLDC uses MOSFETs. Power MOSFET wasn't a thing until the 1970s. Then it took decades to be used commercially. Practical use lags discovery.
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@MichaelClark-uw7ex magnatic? induction is used to create a current? Are you sure? Here's a mind bender, what's an inductor when it is not passing current? Is it still an inductor then? When I buy an inductor am I getting ripped off or is it misleading advertising? I have a drawer full of inductors here but they're just sitting there so are they inductors? Or is the drawer in fact labeled wrong? For extra credit find out what Fleming's right hand rule is. You need to know that.
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@MichaelClark-uw7ex what you say may be an over simplification that could potentially lead to complications. When I go to a supply house and want a spool of wire I do not want to have to ask for a roll of inductor after all.
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@MichaelClark-uw7ex it's not me that's so rigid. It's the laws of nature. A stationary magnetic field by itself will not induce a current. A moving magnetic field will induce a current in a conductor. That's why we use alternating current in transformers and spin generators. We need the field in motion for the magic to happen. Don't blame me, that's just how it is.
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@MichaelClark-uw7ex lines of flux have to move in relation to the conductor. The term often used is, "cut across". The magnetic field itself is an integral part of the transformation process. And yes it does have to be expanding and collapsing (moving) for induction to occur. You could look at it like a saw. The saw doesn't work unless you start to move it. Sure it's still a saw just sitting there but it isn't sawing any.
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The original spinner bot had a gasoline engine in it. It was made by Jamie Hyneman of Mythbusters fame. That machine changed the games. It was kinda a bit too destructive.
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That 0-5V the potentiometer makes is only being used by the ADC in the microcontroller to generate a number. That number in turn is being used to shape the PWM signal the micro outputs. The video ignored the integrated circuit that accepts that PWM signal. Which may be leading to your lack of understanding?
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Lick the battery to see what flavor it is.
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PWM is a digital signal.
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DC motors are cheaper and more robust.
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This is not easy stuff to understand. People who were arguably brilliant had to struggle to discover all of this. They weren't correct immediately either.
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If that wire was like the filament in a bulb it wouldn't have burned so easily. Even not in a vacuum. Modern bulbs use tungsten as the wire.
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You could always move somewhere that does not have hills.
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The current is the same everywhere in a series circuit. You divide the voltage though. Remember when he said resistors aren't like speed bumps? Once you've reduced the current it stays at that reduced rate. More current isn't going to come out of thin air. Though it'd be nice if it did. Voltage drops do differ though.
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@EngineeringMindset if we can hear it then it isn't that high frequency. It's usually referred to as, "voice coiling".
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That's because 1 Ohm resistors aren't 1 Ohm and your measuring equipment has an error too.
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Type joule thief into the search box at the top of this page and find the video by Big Clive. What that circuit can do is nothing short of astonishing. It's a simple boost converter circuit you can make out of electronics trash. There's only 4 parts. But winding the transformer is a bit tricky. You have to figure out which wire is what. It only works the "right" way around. So if it doesn't work you have to swap two of them.
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In a transistor a control signal allows current to flow. That control signal has to be at a potential difference from one end of the flow though. So if you ground that one end then any positive is good for control. If you don't ground it then things get complicated. So we just ground it to keep life simple.
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Transformers hum because they don't know the words.
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Some say there's only one angry pixie in the whole Universe. It just teleports all over the place. It is called the one electron Universe. If that's true the electric companies are really ripping us off. Selling us the same electron over and over.
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