Do you know the channel Technology Connection? Lol

he doesn't get into the nuts and bolts of how they work as much, certainly never seen him dissect and measure.

Yeah not the the electrical stuff as much as you. It was cool seeing inside a running dishwasher though.

@@fmaz1952 He has some decent content, but his affect is so off putting

@@matthiasrandomstuff2221 he occasionally does if the reason to open it is appealing enough or there is more to learn inside. But he doesn't measure current or much of anything else other than temperature. He does go into a lot of history and other details though which can make it a good learning experience

Panasonic for years, but this could convert me.

I wish we had a specific electrics manufacturer so we didn't need to rely on all these general solutions.

I’ve never wanted it less. These are two separate channels.

the water spill was completely unplanned. Though I did boost the audio so you can hear me mutter "oh shit" better.

An engineer for all disciplines.

could be that too on yours

shaded pole fans use pretty low current, even if it's slowing down from friction of the bearings, or not turning at all, the current would just increase to maybe a pretty few amps, if not just an amp. it wouldn't make that much noise either. just the MOT's electromagnetic fields vibrating the metal casing

I had been thinking I should be able to do it by just running some DC into a transformer, but thinking about it more, the control would have too much energy feeding back into it, and realized they had different arrangements of the core and coils.

Totally agree, if this video was silent, that would totally be a Mehdi setup.

Boredom kills

matthias has been getting yelled at on the internet for his dodgy wiring for far longer than most youtubers you can name have even been watching youtube :)

@@somewhere-else - Mehditthias?

Bonus points for using jargon words that actually relate to the video

Criminally underrated comment. Well done.

There's a lot of "just not so" stories on KZfaq (and elsewhere). It also depends on other factors. An unloaded transformer is just an inductor and, near as I can tell, it does not really care where on the incoming waveform you suddenly make the connection. Ideally you make it at the zero crossing of voltage. Since current lags voltage, you would think current would be maximum, and so some people say, but that's stupid; how can there be current without voltage? Well, there isn't and cannot. So what happens is the voltage starts to rise, that builds a magnetic field and the rising magnetic field opposes the applied voltage. But the voltage keeps rising and some current must flow in order to build the magnetic field. Peak current happens at the steepest part of the applied AC voltage; and the steepest part is the zero crossing. It is not AT zero that matters, what matters is dv/dt, the slope of the voltage. In fact, the concept of "zero" doesn't matter to a transformer. So, as the voltage starts back down toward zero, the magnetic field starts to collapse and resists the reduction; or in other words, "squirts" the electrons along in the same direction they already are going. This is why current lags; as the voltage crosses zero and reverses polarity, the current reaches maximum and does not yet reverse polarity. This has some implications for the source, because the current is coming from the source. The voltage reverses but the current wants to continue in the same direction. Since voltage and current don't actually HAVE to be in phase, this current ripples back up to the source still out of phase. IF the source is an inverter or generator, this out-of-phase current can confuse the voltage regulator, current limiters and other things. Not only that, in a totem-pole arrangement of power transistors or mosfets, they cannot source current, but only sink current on the negative half. So the current must stop abruptly and when that happens, instant collapse of magnetic field with corresponding voltage spike that could reach back and destroy the inverter. A *loaded* transformer will have a lot less of this effect and current will be nearly in phase with voltage.

Hmm, indeed. They did consult me for that one a bit. Though I'm sure for the sake of making it an entertaining movie, it won't be that true to reality. Fact is, some of the pivotal moments in RIM's history didn't seem that pivotal at the time they happened -- enough so that in the log I kept of what I did every day, some I didn't consider worth noting.

He's a mad genius! 😆💕👍

email me when you do!

@@matthiasrandomstuff2221 👍👍

Big old color CRTs have deguassing coils in them that run when the monitor sarts up. Same with TVs.

Use a suitably sized TRIAC with zero crossing optocoupler triac trigger chip...for both turning ON & OFF.....a bypass relay can be added to short out the triac a few secs. AFTER turn on & to open a few secs. BEFORE z.c.d. turn off.....that way inrush is always @zero....& there is no turnoff spike either

Good point, I hadn't thought about the residual magnetism contributing, but I'm sure it does.

In smps ..some controller ics for push pull transformer applications have internal logic sequencing for restarting on the next device in cases where such is required after clearing fault / protection conditions... This is only possible as long as the ic is powered up... In case of AC transformers etc. similar can be achieved with memory/latching relays..+ logic circuitry to allow such alternate phase sequencing on .

I imagine variacs are run relatively close to saturation. You need lots of turns to avoid saturation yet variacs only can have one layer of windings.

Microwave oven transformers strike me as constant voltage transformers, though googling around for it, I saw no mention that they are (which is not to say that they aren't). They certainly have weird current waveforms, different from regular transformers.

@@matthiasrandomstuff2221 I have a 1.2kVA ferroresonant CVT. It's got a LOT of iron in it. At least 60 or 70lbs. And a pretty large bank of capacitors. A MOT doesn't have enough mass to provide sufficient power storage at >kW outputs to act as a CVT.

@@unregistereduser2 A microwave transformer also isn't large enough to run a load the size of a microwave oven. Even with forced air cooling they'll still overheat if run continually.

@@unregistereduser2 Diode Gone Wild has made a video about ferroresonant cvt a couple of months ago. Pretty good explanations there.

One reason they are so closed to saturation is the fact they skimp on materials to make them as cheap as possible. Use the least amount of copper and iron and some times the primary has Aluminum windings.

Now J.A.T. comes chipping in before MEHDI..goes BOOM 👍👍

J.A.T. may be studying the feasibility of subwoofer audio signal for driving the microwave tx.....

I just plugged my scope into a 2-prong extension cord, so no ground! And the current sensing resistor was on the neutral side.

The ground clip on a normal scope probe is directly connected to the chassis of the scope and to the ground pin on the power plug. If you were to connect that to hot, you would have a direct short to ground through your scope. In some circumstances you can get away with connecting the the ground clip to neutral, but it's still risky. For example, if you break the neutral on the supply side you'll still get the full load current going through the probe ground. Disconnecting the ground pin on the scope may work, but then the risk changes from blowing your scope to shocking yourself when you touch it. You could just not use the ground clip, but that will give you noisier measurements (since the ground path is through your AC wiring instead of directly from the probe). The best solution is a high voltage differential probe, or isolate your load (such as with an isolation transformer).

@@dack42 Thank you for the detailed answer that was really helpful.

He’s really figured us out eh

that's is a very clever idea for when using a half wave rectifier. Haven't seen that on any microwave oven transformers myself though. But thinking about it, with the voltage doubler typically present, in one direction it charges the cap, in the other direction it uses the voltage stored in the cap, plus the transformers voltage, to power the magnetron

@@matthiasrandomstuff2221 If you search youtube for "microwave magnets" you can see examples of the magnets I am talking about.

correct

we don't home school

When you turn on the unit the capacitor will charge up but won't discharge at all* until the magnetron warms up. *Except for the capacitor's discharge resistor.

Just my variac.

Interesting, just had to look that up!

@@matthiasrandomstuff2221 :) It's not everyday that one gets to add a droplet on knowledge to the ocean that is MW :)

cool!

Nope, the box is sized for a standing wave pattern inside of it based on the wavelength of the microwaves. There will be hot spots and cold spots. Rotating the food averages it out.

The slow start of the rotor dominates for electric motors

Been a long time since we had fuses in north america

I think the fan-like diffusers came before the rotating platters. Not sure which is better, but I think consumers liked the rotating platter cause you can see it do something

IMO the diffuser fan is better. I have a feeling it does a better job distributing the waves, with a turntable the heating pattern is a doughnut. Commercial microwaves seem to go without the spinning turntable but this might just be because a flat bottom makes it easier to clean.

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