Electrical Engineering

12:50 AM

@NickAlexeev haven't heard of this -- could it have been the GE Healthcare MAC 1200 codes? Pdfs all over the place. Welch Allyn might be the next big player in the field. If it's important, I could try to see if our clinical engineering staff has heard of it, but my go to contact there (our alum) now works for Medtronics

W5VO

1:36 AM

@ScientistSmithYT Rectifying a signal is a non-linear operation, meaning that while you may start out with a 60Hz sine wave, you will have many frequency components (harmonics) after the rectifier, extending to 1kHz and beyond. These are the frequency components people are talking about

and the transformer isn't important past converting the voltage from 120VAC to 3.3VAC. Once that's done, all the calculations are performed the same

Scientist Smith YT

3:52 AM

@W5VO Ok. And sorry about forgetting about there not being a transformer in my layout. And forgetting there was a transformer in the picture.

@W5VO So I guess thinking about it. We are now dealing with a changing frequency since its plugged into the mains outlet and not through a transformer that has a certain operating frequency that it is tuned to.

W5VO

@ScientistSmithYT Unlikely to be a significant effect

Scientist Smith YT

@W5VO So now with knowing that the frequency is changing how do we figure that out?

@W5VO oh ok

So let me draw it out. Hopefully I don't make anymore mistakes like this one.

W5VO

but the additional frequency components may confuse some multimeters, leading to an inaccurate reading

Scientist Smith YT

Ok

W5VO

Check this out, it's a great page on explaining frequency components: jezzamon.com/fourier/index.html

Scientist Smith YT

4:00 AM

Ok I will

W5VO

but by just hooking up your meter, you're expecting it to just magically handle all the frequency components you generated correctly. Someitmes this works, and the more expensive your meter the more likely it is to work.

Scientist Smith YT

Here it is. I almost made a mistake at the end. As you'll notice by the VAC being crossed out.:)

W5VO

If you hook a capacitor on the output, you are changing what you are measuring, from the RMS waveform of a harmonic-rich signal, to a fairly constant DC voltage that represents the peak-peak voltage minus a couple diode drops.

Scientist Smith YT

Ok? Got the first part but lost me on the last part.

The part of "constant DC voltage that represents the peak-peak voltage"

W5VO

not sure where I would cut that statement in half. Where specifically did I lose you?

ok

Scientist Smith YT

4:06 AM

What's the difference between peak-peak voltage and constant DC voltage?

Like I know the general difference. But I'm not sure what youre meaning by that?

W5VO

Depends on the circuit :)

but if you put a capacitor on the output, and don't load it with a resistor, then the capacitor voltage won't change significantly once it charges up

it won't decrease, because the diodes prevent current from flowing back into the AC source

Scientist Smith YT

And the resistor varies with the capacitance. Right?

W5VO

what resistance?

Scientist Smith YT

Yup. As far as I know diodes have a voltage rating and amperage rating. If any or both are exceeded there's a leakage. Right?

W5VO

Well, usually exceeding either of those ratings results in an energetic display.

Scientist Smith YT

4:10 AM

Well if theres a large enough capacitance theres an option to put a resistor to mimic load circumstances. But that varies on the capacitance.

Yup! Not that I have experience. But I do have experience with that. Kahboom!

W5VO

What do you mean by "theres an option to put a resistor to mimic load circumstance"

Scientist Smith YT

Yeah. I'm lucky that I had safety goggles and a safety face mask.

So like if you needed to measure the voltage under a load you could use a resistor for the rating you need. So that then you can mimic the load. Of course there are always fluctuations, but at least theres a baseline measurement.

W5VO

I have had similar situations , though I was very lucky and a PCB acted like a blast shield. That failure made me a believer in safety glasses

Scientist Smith YT

Now that is what I call an experiment!!! :)

That happens to every single day. Whether its the big bang in the shop that shakes everything. Or its the flaming ball of fire on my hands. (Cool experiment, look it up) your hands don't hurt, but theres fire on your hands.

W5VO

@ScientistSmithYT What I'm talking about is using no load to figure out what the peak voltage is - increasing capacitance and decreasing resistance will result in an effectively constant voltage. Making the voltage constant helps ensure a good quality reading from even a poor quality meter.

Scientist Smith YT

4:19 AM

@W5VO Oh!

@W5VO Actually that reminds me of a time when I make a constant voltage AC to DC electromagnet. I made it so I could cool it with liquid nitrogen. But I made sure it wasn't cold enough to cause zero resistance. Just cold enough to keep it running.

W5VO

having a good "True RMS" meter can be expensive, and even expensive meters run out of steam above a certain frequency (that will only show up at the least opportune moment).

Scientist Smith YT

It was super powerful! 1.6 tesla. Which is 16,000 gauss. Which is 2 times more powerful than the higheat grade neodymium magnet.

W5VO

I think LN2 temps mean it's a "high temperature" superconductor. Otherwise there's an expensive LHe bill in your future

Scientist Smith YT

Yup. That dis true

What is LN2?

W5VO

I've only had the chance to "play" with LHe once

Scientist Smith YT

4:24 AM

And LHe?

W5VO

Liquid N2 (Nitrogen)

Liquid He (Helium)

Scientist Smith YT

Oh, ive just only known it as Liquid Nitrogen.

W5VO

Another synonym to store away, I suppose

Scientist Smith YT

And nope, there wasn't any high temp superconductors involved.

Just magnet wire. Made of copper.

W5VO

yeah, the superconducting stuff is crazy

Scientist Smith YT

4:27 AM

But high temp superconductors are the opposite for what liquid nitrogen would be used for. Liquid nitrogen would be used for superconductors. I made a little article about it when I was in 9th grade when I was a magnet nerd.

That was my nickname. Only because I taught a highly advanced physics course on it for most of the school year. And even my physics teacher with a PHD was confused. But I've very very closely studied that area extremely well.

I later explained the information to my physics teacher later and she understood everything.

W5VO

"High Temperature" superconductors are still cryogenic

Scientist Smith YT

I'm that one quiet kid that sits in the front. But stays quiet. Even when called to answer a question I stay quiet. But when I'm released I can give very highly advanced magnet knowledge even about electricity. But that's for another time.

Yes that is true cryogenic materials can sometimes not release smells but some other high temp superconductors can. But I wouldn't say they are still cryogenic.

Low temp superconductors also can have those properties as well as high temp superconductors can. It varies on the material type

W5VO

Smells? Are we even talking about the same thing?

Cryogenics

In physics, cryogenics is the production and behaviour of materials at very low temperatures. A person who studies elements that have been subjected to extremely cold temperatures is called a cryogenicist. It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume a gas to be cryogenic if it can be liquefied at or below −150 °C (123 K; −238 °F). The U.S. National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below −180 °C (93 K; −292 °F). This is a logical dividing...

Scientist Smith YT

The variance of the material type can have varying physical and atomical properties. Such as structure, or the bays (alignment is key). And I guess we maybe aren't talking about the same thing.

W5VO

I'd be surprised if you could smell anything that was chilled to LN2 temperatures

Scientist Smith YT

4:40 AM

Yeah :)

Have you ever held liquid oxygen in your bare hands before? Or splashed liquid nitrogen in your face? Oh and submerging your bare hands in liquid nitrogen for 1 second is also fun. (Hint: If all are done right its entirely safe)(Nothing not safe about it if done right)

W5VO

Safety is a relative measure about how much can go wrong before there are catastrophic results.

Scientist Smith YT

All of these uses a neat little effect we all may have seem called the leidenfrost effect. And in some cases what we scientists call the reverse-leidenfrost effect.

Yep

W5VO

I know LN2 is very unpleasant when you use the wrong PPE

Like gloves that allow LN2 to soak in

Scientist Smith YT

Hahaha! Yeah. I could imagine that. I've got a couple severe burns every now and then from liquid nitrogen before. But never from liquid oxygen or even dry ice.

W5VO

I've seen oxygen condense on the side of a LHe dewar

but most of the cryogens I get to play with are under pressure, and need a bit more respect

I do it occasionally for work, so there is an expectation that I have taken precautions to prevent injury or burns to myself and others.

Scientist Smith YT

4:51 AM

Yeah

Well its 10:51 at night here, and I've got to get up at 2 or 3 tomorrow morning. I've got big plans tomorrow, but man I'll be so far off of my game tomorrow. I need sleep. Like even you saw how bad I was yesterday and even today. I just need more sleep.

So I think I'm going to get some sleep. But I'll be on sometime later tomorrow.

W5VO

@ScientistSmithYT Skimping on sleep cheats yourself the most.

Scientist Smith YT

@W5VO Hahaha! Yeah, I guess I know that from experience.

Kortuk

5:06 AM

@jippie US again, but I hope to visit Belgium in January

@NickAlexeev Visited Vladivostok, was incredible, and Kazan is still my favorite city, and if you dont have the soft sign, it was also the dish I would cook mac'n'cheese for Russians in.

W5VO

@Kortuk Long time no see!

Kortuk

@W5VO I know, I was going to message you next :) I saw you in here. It has been too long, how you doing, mate?

W5VO

Crazy busy, working on writing funding proposals

Kortuk

@W5VO Sounds like the fun life.

W5VO

Trying to figure out where I can get a sour brown ale reliably in my area

How about you?

still up to the same?

Kortuk

5:11 AM

@W5VO Up to my eyeballs in a project delivery, the same, but installing new systems instead of maintaining old ones

@W5VO Dream big, if only.

About to finish the first major milestone, so about 13 months of work coming to completion, and the QA is a nightmare. :)

But you would rather the QA is a nightmare if it is a medical device, right?

W5VO

@Kortuk Heh, I have a friend I owe a six pack, and I was (pleasantly) surprised to hear the request

I really don't like being in the reliability path for health/safety, but that's where my work has been leading me lately. Not medical, but similar concerns

Kortuk

@W5VO Agreed. It is a nice choice. Have you been moving around?

@W5VO Yeah, my bigger side projects have been improving how the company handles the employee health/safety.

@W5VO I am sometimes shocked how much energy can leave a faulting breaker. I mean, I know it as an engineer, but is different to be working and realize a safe distance is 70 inches away.

W5VO

@Kortuk I've had the briefing on what to wear for high energy tests, all the way down to the underwear before

Thankfully don't deal with much arc fault risk, or high voltage in general. Mostly high temperature

Kortuk

@W5VO I always laugh at asking someone, "you wore cotton underwear, right?"

@W5VO Interesting.

I for sure owe you a beer next time we are in the same location to discuss it. :)

W5VO

@Kortuk Absolutely. I know better beer locations in the area than that crappy brew-pub (that closed down) now, if you find yourself in my neighborhood

still pretty much in the same area though

Kortuk

5:19 AM

@W5VO I was going to ask if you had moved around. I dont get to that area often, but I still love road trips, so you never know.

@W5VO But sounds like a great idea.

I also have a guest room if you make it to the greater DC area

W5VO

Is that where you're based out of these days?

Don't have a whole lot of travel to that area, but it still happens (inside the company, that is)

@Kortuk Anyways, I've got to hit the hay, or I won't be able to stay awake through all the meetings and calls scheduled for tomorrow. Talk to you later!

Kortuk

@W5VO Yep :)

@W5VO Yeah, I take evening naps to be able to talk to night shift, so I understand. Sleep well!

@W5VO If it happens, let me know

JRE

5:39 AM

@ScientistSmithYT No, damnit. The line frequency is fixed (if it is a wall outlet you are connected to.) The transformer does absolute f all to the frequency. Transformers do NOT do anything to the frequency. Your outlet is at 60Hz. If it varies at all, it will be by very small amounts

Image shamelessly swiped from Wikipedia

The green wave going in is a nice, clean sine wave. Single frequency. In your case, 60Hz.

The green humped thing coming out is changed. That's what a rectifier does when there's no capacitor. Flipping the lower hump from below zero to above zero creates high frequencies. See how pointed the humps are at the zero line? Those are caused by high frequencies.

I'll hunt up an explanation for that later. Gotta run.

forest

7:23 AM

Are questions about, say, Intel x86 CPUs on-topic?

For example accessing the values of one-time programmable fuses?

JRE

7:36 AM

@forest That looks like it'd be on topic.

forest

OK, thanks.

I just wasn't sure because it seems a lot more high-level (abstracted) than most EE.

More JTAG and less logic probes.

JRE

JTAG is most definitely on topic. I was thinking about reading the fuses in code on the processor. That could be a little of a gray area, but since it's the fuses its more EE than stackoverflow.

Since you are reading the fuses via JTAG, that's completely out of stackoverflow and firmly in EE.

forest

Well that's the thing, I don't know exactly how to read it (and searching it isn't helping much). But I'm pretty sure it doesn't involve executing code on the processor (it's not like it's exposed as MMIO).

JRE

Then, yeah. EE.

JRE

8:15 AM

@ScientistSmithYT The frequency is not changing. Rectifying changes the frequency content, but that content is pretty much fixed. It doesn't wander around. It makes multiples of the original frequency.

Here's a couple of examples I made with Audacity

60Hz sine wave. Just like you get from the outlet:

Nothing there but 60Hz.

Here's what happens when you send 60Hz through an ideal bridge rectifier:

The 60Hz is still there. But, it is much weaker. Much of the energy from the 60Hz has been converted to energy in other frequencies. The other frequencies are all multiples of 60Hz. The also go much higher than just the 1000Hz shown in the picture. The mutiple frequencies continue on up.

Theoretically, they go on up forever. Practically, they die off at some point.

In any case, if your meter can't measure the higher frequencies, then it will give inaccurate results.

Also notice that the rectified image also shows a value at 0 Hz. That's DC. That's what we want out of the rectifier. All of the higher frequency stuff is unwanted. You have to filter it out with a capacitor to get clean DC.

JRE

8:34 AM

The second spectrum plot is what the humped green output of the recitifier in the Wikipedia drawing looks like.

JRE

12:54 PM

Correction. The 60Hz is gone. Everything is multiples of 40 Hz. The main peaks are at multiples of 120Hz. The 120Hz makes sense. I'm going to have to look into where the 40Hz stuff is coming from.

Nick Alexeev

1:13 PM

@Kortuk Did the medical device world suck you in too?

JRE

1:35 PM

Got it. Artifact of using a low sampling rate. 2000 Hz/ 60Hz is 33.3333. 0.3333*60Hz is 40Hz. So it's the sampling rate and the signal frequency working together.

adamaero

3:27 PM

Kinda. The silicon hasn't--only the silicone implants suck me in =)

Those majestic...or not so majestic...devices of modern medicine =D

JRE

4:04 PM

@ScientistSmithYT Updated the spectrum images.

60Hz:

60Hz after an ideal bridge rectifier:

It sucks when your tools do things you didn't expect.

Now it properly shows the DC. 60Hz is gone, and all is just multiples of 120Hz.

tairebit

Hello all, does someone knows how to help me with this topic? electronics.stackexchange.com/questions/453785/…

Scientist Smith YT

5:13 PM

@JRE To the first post right after mine. The line frequency does in fact change between 50 and 60 Hz. I went to a friend of mine and asked him about the AC in an outlet. He said it is usually 50-60 Hz but realistically it is actually 49 - 63 Hz.

@JRE Continuation... The transformers do alter the frequency to either 52 (generally 50) or 61 (generally 60) Hz

@JRE the 120 Hz looks kind of like a messy triangle wave. Or a square wave.

@JRE I know that after the electrical energy goes through a phase change the frequency obviously changes. But what does the changing frequency of the AC outlet change for the DC output? These are the kinds of things I run into a lot when doing my experiments. And I usually leave them alone. But this one has me very very intrigued.

JRE

5:28 PM

@ScientistSmithYT Your friend is wrong. It varies, but only slightly.

Less than +-0.3Hz Close enough to "doesn't vary" that we can ignore it.

And, it doesn't matter anyway. The math of an unfiltered rectifier doesn't have any frequency dependent components.

Transformers do not change the frequency. If you over drive them (too much current through the coils so that the core saturates) then they will create harmonics (multiples of the line frequency.) Other than that, the frequency of the on the secondary is the same as the frequency on the secondary.

The Photon

@ScientistSmithYT It's 50 Hz in Europe and 60 Hz in North America. Other parts of the world choose one or the other. Unless your house is run off a very small local generator, it's either 50 Hz there or 60 Hz, not varying sometimes one and sometimes the other.

JRE

6:09 PM

@ScientistSmithYT If you run into those kind of things, then you have run into areas where you are lacking background knowledge.

JRE

6:26 PM

@ScientistSmithYT This is a comparison of the input and output of the 9VAC transformer I've been using:

The voltage and frequency reading don't mean anything. I've move the cursors out of the way so that you can see that the curves cross at the same points on the gray cursor. If the frequencies were different, the crossings would not match.

Scientist Smith YT

6:45 PM

@JRE I asked my friend to measure the waveform and record it for 1 month. This is why I got up so early this morning. His results showed a variance in frequency. He tested a microwave oven transformer and other small transformers. All of the small transformers were soft iron silica core. He also measured and recorded the frequency from the outlet for the whole month. He got again a variety in frequency.

JRE

He should check his equipment. The line frequency varies very little over the day, and averages out to dead on over longer periods. The power companies have to maintain the frequency, else they can't synchronize the generators.

The Photon

@ScientistSmithYT What country is he in?

If his power is coming from a single generator, that might be possible.

If his power comes from a grid with multiple generators connected (like in any 1st world country) then that can't happen without generators blowing up.

Scientist Smith YT

@JRE I've also very closely studied electrical generation and replicated the same methods. Through my experiments I've also came up with the same results. He had a scope to read and record all of the data points, and lay them on a data sheet. He's a very good friend of mine and he knows way more than I do about how to delay phases in electricity as well as how to generate same split phases in a single line.

@ThePhoton His system is directly connected to the grid.

@JRE Actually power companies can still synchronize the generators as long as they keep the same phase at least within a 10 percent error.

@JRE They do it all of the time here. And I'm actually thinking of doing that for the outlets in my shop. So I can connect my in phase appliances into multiple different circuits.

JRE

Yeah, and you can only keep the phase with in 10% if you run at the same frequency. If the frequencies are different, you can't keep the phase constant.

@ScientistSmithYT Who does what all of the time?

Scientist Smith YT

@JRE The power company in my state.

JRE

6:55 PM

The power companies of course keep the frequencies synchronized. You may have phase differences within the building because of different cable lengths or because they are on a different phase of a three phase transformer.

@ScientistSmithYT Does what?

In case you were wondering how small a frequency difference you can see just looking at a scope, here's a comparison of 50Hz (upper trace) and 52 Hz (lower trace):

Scientist Smith YT

The power can be synced from different power plants.

JRE

The both start at time 0, exactly in phase. At one cycle, they are visibly different.

Scientist Smith YT

@JRE Can the software over lap the two seperate phases so I can see the delayed difference in time?

JRE

It isn't made to do that. The green cursor on the right shows the difference, though. Or, use GIMP to cut them into pieces and make them transparent so you can overlay them.

Scientist Smith YT

Yup. And the time is in seconds right?

JRE

7:00 PM

Of course the power companies synchronize the generators. They blow the generators and the transformers to hell if they weren't synchronized.

Scientist Smith YT

Yup

JRE

Yes, the horizontal scale is time in seconds. The vertical scale is relative to full scale. It doesn't matter if you call them volts, or millivolts or rabbits.

Scientist Smith YT

I see that the 52 Hz rises faster on the positive interval than the 50 Hz positive interval.

Haha! So then I can call them jiggawatts? :)

JRE

As long as you remember that jiggawatts isn't related to watts.

Scientist Smith YT

Yeah :)

I know

JRE

7:05 PM

Yes, the 52 Hz signal rises faster. It has to. It must make 52 full cycles in one second where the 50 Hz only has to make 50. The 50Hz has 0.02 seconds to make a cycle. The 52 Hz only has 0.01923 seconds to make a cycle.

Scientist Smith YT

So then if we can find a low and a high enough frequency at some point they'll line up generating an interesting frequency.

JRE

To make the "rise time" more obvious, here's a comparison of 50Hz, 52Hz, and 100Hz:

Scientist Smith YT

At other points they won't line up and a method will need to be used to dampen the potential rise in voltage for the higher frequency.

JRE

They won't line up, and you can't make different frequencies stay lined up. They just add.

Here's what it looks like if all three of those signals were on one wire:

Scientist Smith YT

No not like that. There will be a couple points where they'll line up. But other times they won't. So there will need to be some form of dampener. For the points where they won't line up.

JRE

7:15 PM

I had to scale them. The rabbit scale only goes to 1, and the sum of all three would at times be 3 rabbits.

Scientist Smith YT

Is the 4th section at the bottom of the image the sum of all of the frequencies?

JRE

If you tried the summing thing with a couple of generators, then the non-matching points would cause massive currents to flow. Mixing circuits for audio use resistors to limit the current.

Yep. Bottom section is the sum of the other three.

Scientist Smith YT

Oooh! I've got an idea! So I want to get 3,000 amps at 12 or so volts. And if I summed a couple generators. I could get enough amperage. Voltage... Maybe not. :)

Hmmm... All 3 seem to kind of smoothen out the total frequency... That makes me wonder if we could get a somewhat flat line frequency by adding certain other freqencies?

Where it hits zero it seems to drag on near zero for a little bit. Then drop.

JRE

@ScientistSmithYT Yes. Let's turn this on its head. We added frequencies, and made a wobbly line. Let's make a line, and turn it into frequencies. This is what the fourier transformation does.

Scientist Smith YT

Hmm... I think I get what it is, but I'm not entirely sure.

JRE

7:28 PM

Well, rats. Audacity removes DC before doing the fourier analysis.

Scientist Smith YT

I believe that it covers that 1 frequency can contain multiple different frequencies to then be used separately???

Oh.

JRE

Not one frequency. Any signal can be composed of as the sum of a bunch of single frequency signals.

So, a square wave is the sum of a bunch of sine waves. A particular set of frequency sine waves in phase with one another sum to build a square wave.

Scientist Smith YT

Oh!

JRE

A square wave of 100 Hz is the sum of a 100Hz sine, plus a 300Hz sine, plus a 500Hz sine, an keep adding until you get tired. Each higher frequency is lower in amplitude. So, 200hz is 1/3 the amplitude of 100Hz. 500Hz is 1/5 the amplitude of 100Hz, and so on.

Like this:

Scientist Smith YT

So a square wave is composed of multiple sine waves?

JRE

7:36 PM

Yes.

Any waveform you can image can be built up as a sum of sines.

Scientist Smith YT

Hmmm.. Then why do they call it a square wave? And why does the wiki show a perfect flat line for a square wave on the positive interval?

JRE

Because it is a square wave. It just happens to be composed of a big pile of sine waves.

Scientist Smith YT

Hmm. Interesting

JRE

Here's a square wave - 100Hz:

Certainly looks square to me.

Scientist Smith YT

Well I just scared the ants out of the shop. I charged a bunch of caps up to 25,000 Volts AC. Then released all of the energy all at once.(Simple short) My ear plugs and ear muffs didn't help very much. I wonder how loud it really was. I had ear plugs in while having ear muffs on over them.

Huh. What about a 1 Hz square wave?

JRE

7:43 PM

A 1 Hz square wave would look the same, only the number along the time scale would tell you the diffrence.

Each of those purple peaks is a sine wave. Each one of them is an odd multiple of 100Hz.

Scientist Smith YT

Ok. It seems according to the graph that the higher the frequency the quieter it is. I know that the higher the frequency the less likely we can hear it. But does it actually get even more quiet as the frequency gets higher?

JRE

The difference in amplitude isn't a law. That's what it looks like for a square wave.

Scientist Smith YT

Like say a machine was used to measure how loud it is. Would the machine tell us its getting quieter?

JRE

If you measure a square wave with a machine (which is what I did) then it can tell you which frequencies are how loud in relation to one another.

Scientist Smith YT

Oh

So is the decibel measurement the difference between other frequencies? Or is it the total decibel measurement for each frequency?

JRE

7:53 PM

The dB marks are relative to the maximum volume.

Here's the frequency plot of a modified signal. I just made the frequencies below 3000Hz "quieter."

Because the volumes are different, the sum is different. Care to guess what the wave itself looks like?

I personally wouldn't try it.

Fortunately, I don't have to because I have the waveform here in from of me:

The frequency plot still consists of only odd multiples of 100Hz. Looks quite different from a square wave, doesn't it?

Scientist Smith YT

Hmmm. It does.

It doesn't look anything like a square wave.

JRE

Interestingly enough, you can still see the 100Hz periodicity, despite the 100Hz itself being filter totally out. The sums of the odd multiples conspire to recreate it.

Scientist Smith YT

Yes you can.

JRE

For another comparison, here's a 100Hz sawtooth:

Scientist Smith YT

How do they recreate it if its only the odd?

JRE

8:03 PM

Scientist Smith YT

@JRE I'm having some internet problems and I dont have unlimited data. So just wanted to give an fyi on if I dont respond for a while. Its not me ignoring you, its the internet. Internet problems suck.

JRE

I'd really have to get into a lot of math I'm not real good at to explain they recreate the 100Hz despite only having the odd harmonics.

@ScientistSmithYT Yeah, and I keep spamming you with big pictures. Sorry.

Time to give it a rest anyway. Getting late in the evening here.

See you around.

Scientist Smith YT

@JRE That's got me intrigued. But I'm not going to stop learning this stuff. And no I want these pictures and explanations. This is the best method to use. Don't EVER feel sorry for teaching valuable knowledge.

@JRE But Thank you for the great insight. When my internet is back up I'll come back for more.

The Photon

@JRE Supposedly if you hear 880 and 1320 (and further harmonics) together, you'll hear it as a 440 Hz note.

Scientist Smith YT

@JRE And its not spam if I'm learning or listening. But I assure you I'm learning more and more every day. Its from the great folks like you that keep me wanting to learn more.

JRE

8:13 PM

@ScientistSmithYT Its spam if it breaks your internet. :)

adamaero

I'm going to stop learning this stuff...maybe tomorrow.

Scientist Smith YT

10:48 PM

@JRE I believe I internet is back up. And I just saw your message. I mean if there's enough packages being sent back and fourth on the severs it may crash. :) But I doubt that.

@JRE I contacted the internet company a half and hour after rebooting and rebooting my whole server system. Which also includes the router and modem. It turns out someone hit a line while digging and cut power via internet signal.

The Photon

Anybody have a favorite vendor for cheap (really cheap) power converter chips? (For example, 150 mA buck converter, IC cost << $1 @ qty 10,000)

I have a solution from TI, just hoping to find something cheaper.

Asian vendors not distributed in the US are also acceptable.

Scientist Smith YT

11:12 PM

@JRE I'm curious. How low of a voltage can I run a 110 VAC transformer on? I have a setup of 3 HV transformers that still output the same voltage. I just had to upgrade to a 30 amp outlet. All of them are in phase. The normal RMS voltage is 123-124 VAC.

@JRE When I turn them on and have no load the voltage RMS lowers down to 82.6 VAC. When under a secondary short circuit load the outlet VACRMS goes down to 72 or 73 VACRMS.

The Photon

@ScientistSmithYT You mean a transformer (two coils of wire around a magnetic core) or a transformer (actually an AC-DC power converter)?

Scientist Smith YT

@ThePhoton Nope. It convetts AC to Higher AC Voltage

@ThePhoton They make them for AC-DC or AC-AC conversions.

The Photon

@ScientistSmithYT Do you have a datasheet?

An actual transformer (coils of wire around a core): There's no minimum voltage.

A "transformer" (power converter circuit): You would need the datasheet to find out the minimum voltage.

Scientist Smith YT

Nope not for this one yet. All I know is with 2 running v.s 3 running on the same circuit all I changed was the amperage avalible and kept the voltage the same. The output voltage is still the same as well. Meaning if they are put in series they output 6,960 Volts AC.

So 2,320 VAC each for the output

So are you saying that I could run say 8 or so of these HV transformers on a 100 amp 125 (max Voltage) circuit and still get the same output voltage?

@ThePhoton I do know that with the 30 amp 125 VAC (max Voltage) circuit that anything that has a timer circuit or a clock that is plugged into other circuits that branch from this same circuit restart. Or are sometimes destroyed. My guess is the sudden backwards pulse of electricity due to the lack of electricity.

The Photon

@ScientistSmithYT At the moment I'm still not clear what kind of product you have. Whether it's an actual transformer, or the kind of power converter circuit that some people call a "transformer" even though it's actually a transformer plus some other circuitry.

Scientist Smith YT

11:24 PM

@ThePhoton It is a pure iron cored transformer. No circuitry used. Plugged into mains shop power and has output AC voltage.

It has a primary and a secondary. Nothing special.

The Photon

@ScientistSmithYT Then the output voltage will reduce proportionally if you reduce the input voltage.

But there is no minimum input voltage. You won't damage the transformer by using lower input voltage.

Scientist Smith YT

Then why isnt the output voltage lowering? Its stayed the same.

The Photon

@ScientistSmithYT Either it's not the kind of device you said it was, or you have not measured what you say you've measured.

Or with the "high" input voltage you were saturating the core?

Scientist Smith YT

Its a microwave oven transformer.

MOT's saturate very easily.

I do use a MOT as a ballast. I have the secondary connected in series with the HV end. And the primary shorted together. So 4 MOT's in total. But only 3 that allow current to be produced.

The Photon

@ScientistSmithYT If you have it saturated, the secondary voltage might not change very much when you change the primary voltage.

Scientist Smith YT

11:29 PM

Hmmm... How would I test that? I need something that is a very high load and lowers the voltage while not using more amperage.

I'm already pushing the limits of the 30 amp outlet. I'm using 29.56 amps already and that's being careful. If I turn them all on with one switch it'll draw 38.04 amps.

The Photon

@ScientistSmithYT Not sure about that. Also I don't understand your circuit set up. I'm better with pictures than with words for things like that.

Scientist Smith YT

@ThePhoton How about a circuit diagram? I can get that made for you.

The Photon

@ScientistSmithYT Might help. But I'm definitely no magnetics expert.

Scientist Smith YT

@ThePhoton Yeah just leave the magnet nerd to this task. :) let me draw it for you.

Alright just 1 more minute I'm sending the diagram

The key

The circuit diagram

The Photon

11:51 PM

@ScientistSmithYT You're measuring the secondary voltage with no load on the secondary?

My thought is to avoid saturation, you want to allow some current out of the secondary.

Scientist Smith YT

Well the saturation or flux loss gets worse as I allow the short circuit to occur.

And no. I measured the secondary voltage with a load and without a load. The voltage was around the same number. And then I measured the input voltage under load and while not under a load. Not under a load it said 123 VAC under a load it said 72 or 73 VAC.

The problem with letting too much current go is that it saturates the core even more. Which causes extreme heating. Ive had to use a refrigeration unit to keep them at least touchable.

I extracted the freezer unit and refrigeration unit. I put the refrigeration unit on before I turn the HV transformers on. And for a backup I can turn the freezer unit on. Which can cool down to -8 degrees Fahrenheit.

I use a small AC fan to circulate the air pushing the air directly through the HV transformers.

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Electrical Engineering