#garfield Logs
Feb 25 2025
#garfield Calendar
07:31 AM rue_mohr: wow, I didn't know this, rump just wanted to be getting the aluminum from russia the whole time
10:42 AM aandrew: well, I did the turns test
10:42 AM aandrew: wrapped ten turns around one of the outer legs of the transformer (no room to wrap anything around the central leg)
10:42 AM aandrew: pri sec test
10:43 AM aandrew: 19.9 101.8 1.55
10:43 AM aandrew: 25 128 1.95
10:43 AM aandrew: 40.1 206 3.12
10:43 AM aandrew: pri is 120V, sec is 600V, test is my ten turns
10:47 AM aandrew: 19.9/1.55 is 12.84:1
10:47 AM aandrew: 25/1.95 is 12.82:1
10:47 AM aandrew: 40.1/3.12 is 12.85:1
10:48 AM aandrew: so I can estimate that the 120V winding is probably around 128-130 turns
10:50 AM aandrew: and that would make the 600V winding 5x that, but checking the numbers
10:50 AM aandrew: 101.8/1.55 is 65.7
10:50 AM aandrew: 128/1.95 is 65.6
10:50 AM aandrew: 206/3.12 is 66.0
10:51 AM aandrew: which would be about 655-660 turns
10:51 AM aandrew: so the numbers for pri:test and sec:test are in rough agreement
10:59 AM aandrew: https://ibb.co/CNKGKBJ
10:59 AM aandrew: https://ibb.co/JWCsgWzy
10:59 AM aandrew: pics of the transformer and winding
10:59 AM aandrew: I call that ten turns
11:04 AM aandrew: I have to go back now and see if I can find my notes/LLM session and see how far off it was
11:15 AM VanUnamed_ is now known as VanUnamed
12:09 PM aandrew: ok
12:10 PM aandrew: I had asked it to compute the turns for a transformer using EI-219 laminations for a total thickness of 73mm and operating at 60C and 75% of flux density (which is high, 50% should probably be the target)
12:10 PM aandrew: I had asked it for a primary of 240V and a secondary of 24V (shoudl really be 48)
12:11 PM aandrew: it told me back then that I'd want 130 turns and recommended 14AWG with a primary current of approx 10A for 2.5kVA
12:12 PM aandrew: asked to recompute for 50% of flux density and it came back with 195 turns for the 240V winding
12:14 PM aandrew: interestingly, when I asked it to estimate the number of turns based on 73x73mm cross sectional area (EI-219) and a measured 43mH inductance at 100Hz, it told me approximately 36 turns which is WAY low
12:27 PM aandrew: I asked it to show its work for that number of turns and it updated the answer to 51 turns which still appears low by roughly 60% based on the measurements I took today
12:30 PM aandrew: N = sqrt((L x l)/(u0 * ur * A)), L = inductance (43mH), l = approximate magnetic path length which it says is 200mm (not sure where it got that), u0 = 4*pi*10^-7 (permeability of free space), ur = 1000 (relative permeability of silicon steel), and A is cross-sectional area which is 73mm x 73mm (0.005329 m^2)
12:36 PM aandrew: https://ibb.co/7skcjcM
12:36 PM aandrew: hm, my math doesn't add up
12:37 PM aandrew: I get 0.0086 for the numerator too, but I get 6.6967 x 10^-5 for the denominator
12:40 PM aandrew: 4*pi is 12.566, 10^-7 * 1000 is 10^-4, and .073^2 is 0.005329... 12.566 * 10^-4 is .012566 * 0.005329 is 6.696 * 10^-5, not 3.35 * 10^-6?
12:40 PM aandrew: wtf
02:02 PM aandrew: so now I'm pretty sure it's coming down to the value of u0 and ur. wikipedia agrees that the permeability of free space is 4*pi*10^-7 but other sources say it's not the same, and the relative permeability of "silicon steel" seems to be a number pulled out someone's ass. My guess is that the ur of this specific steel is different than what is assumed
02:22 PM aandrew: so if 43mH is about 128 turns and assuming u0 is good, that should put the ur at ...80ish? that's extraordinarily low
03:05 PM rifraf: aandrew are you making a transformer or is this something else?
03:08 PM aandrew: I have a 2.5kVA power transformer, 120:600. I measured the primary (120V) winding inductance as 43mH @ 100Hz. I then wrapped 10 turns around one of the legs and put 20, 25 and 40V on the primary, measuring the voltage on the secondary and on my test coil of 10 turns
03:08 PM aandrew: came out with ~12.8:1 pri:test, ~65.5:1 sec:test and 1:5 pri:sec
03:09 PM aandrew: since I know the turns on the test coil, that means the primary should be ~128 turns and ~660 turns on the secondary, which also makes sense since 128*5 is 640
03:10 PM aandrew: so, since i know the primary inductance and am fairly certain of the inductance, I want to compute the relative permeability of the core
03:10 PM aandrew: but the numbers I'm coming up with seem ridiculously low (~171)
03:11 PM aandrew: the transformer is an EI-219 core and is 73mm thick (basically the center leg, which is what the pri/sec are wound on is 73mm wide and 73mm "thick", so the cross-sectional area is 5329mm ^2
03:12 PM aandrew: u0 is 4*pi*10^-7 H/m (per wikipedia)
03:13 PM aandrew: so I'm using ur = (L * l)/(u0 * N^2 * A, L = inductance (H), l = magnetic path length (m), N = turns and A = cross-sectional area (m^2)
03:14 PM aandrew: basically I'm trying to make the measured values match up with the math just for my own understanding
03:15 PM aandrew: EI-219 core measurements from http://www.bongtra.co.kr/core/core_for_transformer.pdf (single phase with 4 holes) which line up nicely with what the physical device is
03:15 PM aandrew: A = 219mm (overall length of core)
03:16 PM aandrew: B = 146mm (overall height of core)
03:16 PM aandrew: C = 73mm (length of middle pillar, pdf uses F for this)
03:17 PM aandrew: D = 36.5mm (window width, also is height of I piece and width of the "E" legs)
03:18 PM aandrew: E = 109.5mm (height of middle pillar)
03:18 PM aandrew: I'm computing the magnetic path length as 440mm (basically two loops where you go from middle pillar around left side, and then same on right side)
03:21 PM aandrew: if the EI core is positioned like [ | ] then I see 3 * (D + E) (the three vertical bars, left, middle, right) plus 2 * (A - D) (top and bottom)
03:22 PM aandrew: 3 * (36.5 + 109.5) + 2 * (219 - 36.5) is 438 + 365 or 803mm which is almost double my previous calculation for magnetic path length
03:23 PM aandrew: that gives me ur of 31.4 which is even lower so obviously I'm messing something up
03:23 PM aandrew: the math and actual values should be in the same damn ballpark
03:54 PM aandrew: if I compute the path length again, differently, I get 730mm. (three vertical pillars are 438mm (3*(E+D)), then the four top/bottom sections are 292mm (4*(36.5+36.5)). I don't know if I should add another E+D since there are technically two loops through the middle or not but either way that makes the ur worse not better
03:54 PM aandrew: I shoudl re-measure the inductance, maybe I fucked that up
06:13 PM rue_mohr: aa
06:13 PM rue_mohr: aandrew, your going crazy
06:14 PM rue_mohr: how many volts was 10 turns
06:14 PM rue_mohr: you burted out too many numbers
06:14 PM rue_mohr: stop trying to rewind the primary, it was designed for that transformer
06:14 PM rue_mohr: work out the turns/volt they used and just use that
06:14 PM rue_mohr: if its 1V/turn and you need 24V, put on 24 turns.
06:15 PM rue_mohr: dont bother with inductance or the phase of the moon
06:15 PM rue_mohr: just turns/volt, as designed, via the primary 120V winding
06:18 PM rue_mohr: and you dont have to take the core apart
06:18 PM rue_mohr: if you take it apart, it will look like a train hit it by the time you re-assemble it
06:21 PM rue_mohr: transformer design is done with all sorts of magic values that engineers make up themselves from years and years of experience building transformers
06:22 PM rue_mohr: what you find online about it is from the 3rd graders learning the basic concepts and has nothing to do with the actual real design of good transformers
06:22 PM rue_mohr: I know if seems like it should
06:22 PM rue_mohr: if I could find you the old books I'v seen
06:23 PM rue_mohr: "0.4 is a good value for this"...
06:26 PM rue_mohr: one of the shockers was when they made relays
06:27 PM rue_mohr: the wire calculation in ohms, cause you use the wire resistance to set the current
06:36 PM aandrew: I will have to rewind the primary, either to become the secondary (240V center tapped) or as the 48V primary
06:36 PM aandrew: rue_mohr: rough ratio primary:test is 12.8:1. Since I had 10 turns on the test winding that means the primary likely has 128 turns
06:37 PM rue_mohr: no
06:37 PM rue_mohr: just how many volts/turn
06:37 PM rue_mohr: just volts/turn, no ratios
06:37 PM rue_mohr: was 10 turns 12.8V?
06:37 PM aandrew: no
06:38 PM rue_mohr: how many volts was 10 turns
06:38 PM rue_mohr: just how many volts/turn
06:38 PM rue_mohr: thats the number you need to hold to
06:38 PM aandrew: apply 20V on 120V primary of unknown turns, got 1.55V on ten turn secondary
06:38 PM rue_mohr: ugh
06:38 PM aandrew: so that would be 0.155V/turn
06:38 PM rue_mohr: just put 120 on the 120
06:39 PM rue_mohr: its not .155V
06:39 PM rue_mohr: thats way too low
06:39 PM rue_mohr: WAY WAY too low
06:40 PM rue_mohr: normal numbers are 0.5-1V/turn
06:40 PM rue_mohr: can you put 120V on the 120V winding?
06:40 PM aandrew: I could be "down in the mud" with too low a primary voltage applied, you're right, that's one of the theories I have
06:40 PM rue_mohr: you dont have to lick the 600V winding
06:41 PM rue_mohr: just a 2 second test
06:41 PM aandrew: I put 20, 25 and 40V on the primary and got consistent results but I have to go back down to try 120
06:41 PM rue_mohr: let the meter settle and turn it off
06:41 PM rue_mohr: even just 1 turn
06:41 PM rue_mohr: did you see the transformer I did on the weekend?
06:41 PM aandrew: no
06:42 PM rue_mohr: damnit, my file server is locked up and I cant do anything till its back
06:42 PM rue_mohr: check bluesky or mastadon I posted it on both
06:44 PM rue_mohr: in my case I removed the secondary, looped a wire around it to my meter, applied 120V to the primary, read 1.05V on the test loop, and I was good
06:44 PM rue_mohr: 1V/turn
06:44 PM rue_mohr: thats the design factor
06:44 PM rue_mohr: good for all the VA its rated for
06:46 PM rue_mohr: you keep trying to calculate the arrowdynamic drag of the wheels, and the soap box racer isn't getting finished.
06:46 PM aandrew: 100V produced 7.7V, 120 produces 9.3
06:47 PM rue_mohr: and didn't you WANT a 120V winding for what your building?
06:47 PM rue_mohr: ok!, .93V/turn!!!
06:47 PM aandrew: that’s still 0.7V/turn on the secondary
06:47 PM rue_mohr: thats beleivable!
06:47 PM rue_mohr: 9.3V on 10 turns is .93V/turn
06:48 PM aandrew: Yes. You don’t have to normalize it?
06:48 PM rue_mohr: .93V/turn is between 0.5V/turn and 1V/turn - passes sanity check
06:48 PM rue_mohr: if you play with the voltage on the 120V winding, your messing with the magnetic operating point
06:49 PM aandrew: Oh I see, yeah that makes sense
06:49 PM rue_mohr: aka, either driving it too hard or not as hard as you can (core is larger than it need be)
06:49 PM rue_mohr: 0.93V/turn <--- design to that!
06:50 PM aandrew: I still have to rewind the primary
06:50 PM rue_mohr: its over the 600V winding?
06:50 PM rue_mohr: I like it when they are side by side and you can just leave it
06:50 PM aandrew: Hm? 600V winding is on top of 120V winding
06:50 PM rue_mohr: so why would you need to redo the 120?
06:51 PM rue_mohr: its made of the wire that best suits the power rating of that core
06:51 PM aandrew: Because I need 240 center tapped and 48V
06:51 PM rue_mohr: hmm
06:51 PM rue_mohr: you just need another 120V winding then
06:52 PM rue_mohr: I suppose you COULD foldback-parallel rewind it but :
06:52 PM rue_mohr: :/
06:52 PM aandrew: 120/x = .93/1, primary should be 129 turns
06:52 PM rue_mohr: sounds like 130 and error
06:53 PM aandrew: So that cross check is nice but still doesn’t help me understand why the ur is so ridiculously low when calculated
06:53 PM aandrew: Yes it does
06:53 PM rue_mohr: cause your not taking something into account that a pro transformer engineer knows
06:54 PM aandrew: That’s my point of the exercise. I want to know what
06:54 PM rue_mohr: some old guy who grumbles a lot about how people dont do things right anymore
06:54 PM rue_mohr: maybe it accounts for the ur of the resin on the laminations
06:55 PM rue_mohr: maybe the distributed gap
06:55 PM rue_mohr: maybe the metal isn't quite what you think it is
06:56 PM rue_mohr: the real engineers always have AT LEAST 1 fudge factor they pull out of their ass
06:56 PM rue_mohr: I like to use 200%
06:56 PM rue_mohr: for overeng.
06:56 PM aandrew: 38.5mH @120Hz
06:56 PM rue_mohr: its going to dissipate 1W? I want to use a 2W resistor
06:57 PM rue_mohr: I dont always get that, cause sometimes its just too much, but its a random number I just do
06:57 PM aandrew: Well to have to use 100% on resistors, their power rating is usually at 100C or something
06:57 PM rue_mohr: yea, part of why I back off on them so much
06:57 PM aandrew: 950mH on the 600V winding
06:58 PM rue_mohr: but someone doing with math could be like, "oh its 980mW, so I'll use a 1w resistor, why did Rue use 2w?"
06:58 PM aandrew: Only the inexperienced
06:59 PM rue_mohr: I had a number of geezers tell me,
06:59 PM rue_mohr: "find out what the v/turn is, and use that"
06:59 PM aandrew: No I get it and agree. I want to understand the math too
06:59 PM rue_mohr: and your inductances dont add up at all
07:00 PM aandrew: I want to know the fudge factors
07:00 PM rue_mohr: we ALL do
07:00 PM rue_mohr: their top secret
07:00 PM aandrew: Nah just obscure and based on experience
07:00 PM aandrew: I’ve never been good with inductors
07:00 PM rue_mohr: if you have a few transformers by the same guy, you can often reverse engineer it to one factor thats "kinda close" to what they use
07:01 PM rue_mohr: your sure the 600V winding wasn't more like 192mH?
07:01 PM rue_mohr: you being dislexic :]
07:01 PM rue_mohr: ?
07:02 PM aandrew: Nope
07:02 PM rue_mohr: huh
07:02 PM rue_mohr: series resistance must be messin with it
07:02 PM rue_mohr: its 4kVA?
07:03 PM aandrew: Path length measured with a fucking ruler: pillars are 155mm ea, distance across one opening: 100mm
07:03 PM aandrew: 2.5 yes
07:03 PM rue_mohr: oh you cant do the path length like that
07:03 PM rue_mohr: there is a fudge factor for the turn the magnetics take
07:03 PM rue_mohr: I cant google right now
07:03 PM aandrew: 510mm per “window”, two windows is 1020mm
07:04 PM rue_mohr: "producing wound components" by university of (I cant remember)
07:04 PM aandrew: If it’s just three pillars (don’t count the middle twice) then it’s 155x3+400 or 865mm
07:05 PM rue_mohr: www.ee.surrey/ac.uk
07:05 PM rue_mohr: what do you mean 3 pillars?
07:05 PM rue_mohr: you dont have a 3 phase transformer do you?
07:05 PM rue_mohr: EI isn't it?
07:05 PM aandrew: [ | ]
07:06 PM aandrew: Left, middle, right pillar
07:06 PM aandrew: Windings are on middle pillar
07:06 PM aandrew: No it is single phase
07:06 PM rue_mohr: omg, the file server is abck and its openign eveything I asked it to
07:06 PM rue_mohr: lmgtfy
07:07 PM aandrew: Ok going back upstairs. Hate typing on phone
07:07 PM rue_mohr: https://pe2bz.philpem.me.uk/Comm01/-%20-%20Parts-NonActive/-%20Inductor/MakeCoils/index.html
07:08 PM rue_mohr: this is that grade 3 thing I was talking about
07:08 PM rue_mohr: this is not how engineers do it
07:09 PM aandrew: and yeah primary resistance is too low for my meter (0.3 ohm but leads are 0.3 ohm) and secondary is like 2.2 ohm so around 1.9. I have a mohm meter but it's not usable right now
07:09 PM rue_mohr: https://pe2bz.philpem.me.uk/Comm01/-%20-%20Parts-NonActive/-%20Inductor/MakeCoils/terms.html
07:10 PM rue_mohr: "This is all a bit approximate; but bear in mind that since manufacturing tolerances on permeability are often 25% there isn't much point in being more exact."
07:11 PM rue_mohr: ^^ a long road of 'we will just fudge that'
07:12 PM rue_mohr: tell me what you work out for the fudge factors between "the rules of physics" and the transformer made by a 50yr vetrin
07:15 PM rue_mohr: a good start might be working out what they did with the peak flux density
07:15 PM aandrew: nice link
07:15 PM rue_mohr: yea, it taught me 80% of what I knew
07:16 PM rue_mohr: and to hate the world for things like tesla vs gauss
07:16 PM rue_mohr: a what is what and WTF
07:16 PM aandrew: heh
07:17 PM aandrew: but yeah if I'm doing 1V/turn I still need 240 turns on the primary and 48 on the secondary. not bad turn counts but will be a pain and I think taking this transformer apart is going ot suck bigtime
07:18 PM aandrew: it is nice though that the way I was doing it to deterine turns worked out to the same numbers, but the inductance-to-turns and working out ur didn't work worth a shit
07:18 PM rue_mohr: I still have some issues around MMF and magnetic flux
07:18 PM aandrew: I wonder what it looks like if I ran the numbers on the secondary instead
07:19 PM rue_mohr: taking it apart isn't the issue
07:19 PM rue_mohr: getting it back together is the issue
07:19 PM rue_mohr: one does not simply re-assemble the laminations
07:20 PM rue_mohr: aandrew, you know that the 120V winding has about 130 turns
07:20 PM aandrew: yeah I've taken apart enough of them to know it's a royal pain
07:20 PM aandrew: putting them together I would need to clean the laminations well
07:20 PM rue_mohr: so whats the peak mmf
07:21 PM rue_mohr: aandrew, yes no, cause if you take the finish off, they short
07:21 PM rue_mohr: their black?
07:21 PM aandrew: blackish yes, hard to tell under the resin
07:21 PM rue_mohr: FeO3
07:22 PM rue_mohr: sometimes they are assembled lazy and the EI aren't completely interleaved all the way thru it
07:22 PM aandrew: hm, using the secondary turns/inductance and 1020mm path length, ur is coming in at 350 which is still low for a power transformer
07:22 PM rue_mohr: and sometimes they run a tig welder across it all
07:22 PM aandrew: yeah I have to pull the bolts off to see, definitely no weld that I can see
07:22 PM rue_mohr: forget the inductance
07:22 PM rue_mohr: you have 120VAC
07:22 PM rue_mohr: have you 130 turns
07:23 PM aandrew: yes, and?
07:23 PM rue_mohr: there is a specific MMF for that
07:23 PM rue_mohr: the doc online uses amp-turns
07:23 PM rue_mohr: BUT
07:23 PM rue_mohr: its also calculable by volt-seconds
07:23 PM rue_mohr: or otherwise dv/dt
07:24 PM rue_mohr: this is a positive number you can be sure of
07:25 PM rue_mohr: from that, you can guess the ur of the iron and work out what the peak flux is
07:25 PM rue_mohr: and there is the core size in there somewhere, and by the way, you only use the area of the inner leg
07:25 PM rue_mohr: god, for someone who is no good at this, I know a lot
07:26 PM aandrew: yeah you use the cross sectional area which is 5329mm^2
07:26 PM rue_mohr: sure
07:26 PM rue_mohr: of just the inner leg
07:26 PM aandrew: but the MMF is assuming a relative permeability where I want to compute that
07:26 PM aandrew: yes just the inner leg. 73mm x 73mm
07:26 PM rue_mohr: yea, the mmf is all over the map becasue its AC
07:27 PM rue_mohr: so at the zero crossing dv/dt will be max and that will relate to the peak mmf
07:27 PM rue_mohr: which is multiplied by the iron to make a magnetic flux
07:27 PM aandrew: it's saying 1544A-t, but i have no feel for whether that's bullshit or not
07:28 PM rue_mohr: yea, sorry, past the limit of the help I can give
07:28 PM rue_mohr: I just use the volts/turn and design to that
07:28 PM rue_mohr: cause there is a LOT of math behind it
07:29 PM aandrew: yeah designing it wasn't ever the issue, understanding it was :-)
07:29 PM rue_mohr: and magic constants
07:29 PM aandrew: but I really appreciate all the guidance, trully
07:29 PM aandrew: wow can't spell
07:29 PM aandrew: truly
07:29 PM rue_mohr: the magnetic flux density should be under 200mT
07:29 PM rue_mohr: (a random note in my book)
07:30 PM aandrew: this is saying it's 704mT
07:30 PM aandrew: but like I said I don't know if it's lying which it probably is
07:30 PM rue_mohr: sounds too high, BUT
07:30 PM aandrew: I can design to V/t and just run with it
07:30 PM rue_mohr: my note is probably for ferrite and iron can be higher
07:31 PM rue_mohr: oh ohho
07:31 PM rue_mohr: antoher note
07:31 PM rue_mohr: material | Bsat
07:31 PM rue_mohr: iron | 1.5 - 2T
07:31 PM rue_mohr: iron | 1.5 - 2T (50-60Hz)
07:49 PM aandrew: sounds right, I see similar
08:07 PM rue_mohr: yay, I got the linkage on this power supply variac working
08:08 PM aandrew: heh I had to fix my variac this morning too. it would not turn and the knob was loose too. turned out one of the wires connecting the actual variac to the power cord had got tangled around the wiper where the wire connects
08:16 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1330899.jpg
08:16 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1330901.jpg
08:16 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1330902.jpg
08:16 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1330904.jpg
08:17 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1330921.jpg <-- my variac, 3kva, from an automatic votlage regulato
08:17 PM rue_mohr: r
08:17 PM rue_mohr: just got the knob working today, I'm so happy :]
09:33 PM Tom_L: that looks dangerous
10:04 PM rue_mohr: :]
10:04 PM rue_mohr: https://bsky.app/profile/ruenahcmohr.bsky.social/post/3lj2cqt42lk2q
10:04 PM rue_mohr: video!
10:05 PM rue_mohr: that does the 120V scaling, then I have another transformer for isolation and stepdown, I have some 40A rectifiers
10:05 PM VanUnamed: hey rue_mohr having fun?
10:05 PM VanUnamed: tell me something
10:05 PM rue_mohr: mm
10:05 PM VanUnamed: can i change the stator on my makita drill
10:06 PM VanUnamed: it has a 110v one.
10:06 PM VanUnamed: but i can buy the 220v for the same model
10:06 PM VanUnamed: do i need to also change the rotor?
10:06 PM VanUnamed: chatgpt INSISTS It's not the case.
10:06 PM VanUnamed: https://pastebin.com/qX0dR5wh
10:06 PM rue_mohr: universal motor?
10:06 PM VanUnamed: yes
10:07 PM VanUnamed: im tired of lugging around 15kg converter transformer.
10:07 PM rue_mohr: the votlage is dropped across the rotor, not the stator
10:07 PM VanUnamed: what do you mean?
10:07 PM rue_mohr: -mmmmmm--[O]--
10:07 PM rue_mohr: mmmm is the stator
10:08 PM rue_mohr: O is the rotor
10:08 PM VanUnamed: so i cant do it?
10:08 PM rue_mohr: the voltage is dropped across the rotor, not the field
10:08 PM rue_mohr: mmm is field
10:08 PM rue_mohr: stator is what
10:08 PM rue_mohr: universal motor is series wound
10:09 PM rue_mohr: change the rotor
10:09 PM rue_mohr: there is not supposed to be voltage drop on the field
10:09 PM rue_mohr: there technically is, but its trivial
10:10 PM rue_mohr: "ChatGPT said:
10:10 PM rue_mohr: A universal motor is a series-wound motor that can operate on both AC and DC power. It is commonly used in power tools, vacuum cleaners, and small appliances due to its high speed and torque characteristics."
10:10 PM VanUnamed: but it;s the stator windingds that are different.
10:11 PM VanUnamed: not the rotor.
10:11 PM rue_mohr: field
10:11 PM rue_mohr: chatgpt:
10:11 PM rue_mohr: "In a universal motor, the most significant voltage drop occurs across the armature (rotor) and the field windings because they are connected in series. However, depending on operating conditions, different parts contribute to voltage drop in the following ways:"
10:11 PM VanUnamed: thanks for now confusing my ideas even more.
10:11 PM rue_mohr: pff
10:12 PM rue_mohr: its goofy
10:12 PM VanUnamed: answer not clear.
10:12 PM VanUnamed: if i can replace one or the other, its worht it
10:12 PM rue_mohr: the armature, not the field is the votlage drop
10:12 PM VanUnamed: otherwise its too expensive.
10:12 PM rue_mohr: replace the armature, not the field
10:12 PM rue_mohr: why is an armature more expensive than a field?
10:13 PM VanUnamed: it must be either or.
10:13 PM VanUnamed: both, is too expensive
10:13 PM rue_mohr: no, the field should be fine
10:13 PM VanUnamed: chatgpt says stator, you say rotor. now how do i know which is which
10:13 PM rue_mohr: its wrong
10:13 PM rue_mohr: the field is current based
10:14 PM rue_mohr: the armature develops the backEMF (voltage)
10:14 PM rue_mohr: look at the motor
10:14 PM rue_mohr: look at the wire guage of the armature and field
10:14 PM rue_mohr: the REASON the field uses such heavier wire is that it operates via current
10:15 PM rue_mohr: all that fine wire on the armature does the votlage drop (not by resistance)
10:15 PM rue_mohr: and god dont believe chatgpt
10:15 PM VanUnamed: chatgpt has to be right.
10:15 PM rue_mohr: your doomed
10:15 PM VanUnamed: you do realie i dont know anyone that knows about heat exchangers
10:15 PM VanUnamed: and now it's all chatgpt making?
10:15 PM VanUnamed: most, at least.
10:16 PM VanUnamed: with the drill, instead, if i buy the wrong part, i waste money and none of it will be refundable.
10:16 PM rue_mohr: I'm reading thru its answers to me and its strange
10:16 PM VanUnamed: now follow me with this
10:16 PM rue_mohr: so you not gonna believe me?
10:16 PM VanUnamed: the FIELD coil
10:16 PM VanUnamed: has one coil on each side
10:16 PM VanUnamed: OK?
10:16 PM rue_mohr: so, tell me this
10:17 PM VanUnamed: so you get windings, that do 55v and 55v.
10:17 PM VanUnamed: the 220v one has 110 and 110
10:17 PM VanUnamed: am i wrong?
10:17 PM rue_mohr: in a PERMANTENT MAGNET MOTOR, what determines the votlage of the motor, the field winding or the armature winding?
10:17 PM VanUnamed: the armature.
10:18 PM rue_mohr: yea, its the same in a series wound
10:18 PM VanUnamed: but, also the field coil has to be with the right windings or it fries
10:18 PM rue_mohr: no
10:18 PM rue_mohr: as with a permanent magnet motor, you can have no field and the motor will still turn
10:18 PM rue_mohr: the STRONGER the field, the SLOWER the motor turns
10:19 PM VanUnamed: how can chatgpt be wrong.
10:19 PM rue_mohr: at high torque, a series wound motor develops less backEMF, so there is more current and because of the series wiring, there is a stronger field
10:20 PM rue_mohr: your seriously asking me that?
10:20 PM rue_mohr: MOST things its wrong about
10:20 PM rue_mohr: often in cursed ways
10:20 PM rue_mohr: ok
10:21 PM rue_mohr: if you dont beleive me, put a voltmeter across the bushes and run it
10:21 PM VanUnamed: the stator sets the voltage requirement it keeps saying.
10:21 PM rue_mohr: with no load, you will see almost all the voltage across the armature
10:21 PM VanUnamed: the stator and rotor are in serie, so they share the same current regardless of voltage.
10:21 PM VanUnamed: "If you sqap the stator with the 220v one, the current will adjust and the rotor will work fine"
10:21 PM VanUnamed: so, it's human vs machine.
10:21 PM rue_mohr: no
10:22 PM VanUnamed: you both make sense. Lol
10:22 PM rue_mohr: PUT A FEAKING VOLTMETER ACROSS THE BRUSHES
10:22 PM VanUnamed: and what would i see
10:22 PM rue_mohr: all the voltage across the armature with no load
10:23 PM rue_mohr: and only a little bit of voltage lost to the field under high load
10:23 PM rue_mohr: the backEMF of a motor is generated by the armature, not the field
10:24 PM rue_mohr: and the backemf is what sets the speed
10:24 PM VanUnamed: i dont want to imagine it being wrong about pressure vessel welding and heat exchanging tech.
10:25 PM VanUnamed: it cannot be even imagined, that it's wrong.
10:25 PM rue_mohr: if you double the turns on the armature, you will get half the speed on the motor (and twice the torque)
10:25 PM rue_mohr: are you actually serious?
10:25 PM VanUnamed: yes
10:25 PM rue_mohr: please tell me your kidding
10:25 PM VanUnamed: experts are very expensive
10:25 PM rue_mohr: oh god
10:25 PM rue_mohr: and right!
10:25 PM VanUnamed: so chatgpt is the official advisor of my socialist republic.
10:25 PM VanUnamed: you sound convincing too
10:25 PM rue_mohr: hahah
10:25 PM VanUnamed: but, i am too ignorant to tell
10:26 PM rue_mohr: thats becasue I took motor theroy like 7 times in schools
10:26 PM VanUnamed: issue is, i buy the wrong part, no one gives me the 24 eur that it costs.
10:26 PM rue_mohr: and on top of that knew old farts that modified motors
10:27 PM rue_mohr: how good is this drill that your going to all this trouble anyhow?
10:27 PM VanUnamed: their disclaimers about chatgpt being wrong prevents me from charging bill gates with 24 eur of wrong part boight.
10:27 PM VanUnamed: very, good.
10:27 PM VanUnamed: HR2610 makita
10:27 PM rue_mohr: chatgpt is Elon you nit.
10:27 PM VanUnamed: i paid it very, very little cus it had a small fault, and 110v UK style
10:27 PM VanUnamed: and i have the transformer, but its a pain
10:27 PM VanUnamed: its so heavy, wtf
10:28 PM rue_mohr: huh, hammerdrill
10:29 PM VanUnamed: https://www.ebay.co.uk/itm/116490097553
10:29 PM VanUnamed: see this?
10:31 PM VanUnamed: thats the 220v one
10:41 PM rue_mohr: oh interesting
10:42 PM rue_mohr: they just postfix a letter on the armature part number for the different voltages
10:42 PM VanUnamed: so you are right and chatgpt is wrong?
10:42 PM rue_mohr: I cant find the diagram I'm looking for
10:42 PM rue_mohr: to prove it to you
10:43 PM rue_mohr: but I'v NEVER seen a powertool made in more than one voltage
10:43 PM VanUnamed: no?
10:43 PM rue_mohr: there should be a blowup diagram that shows the replacement part numbers for the same model drill, but different votlages
10:43 PM VanUnamed: the uk is dumb.
10:44 PM VanUnamed: https://www.sparepartsworld.co.uk/product/SPARE_HR2610
10:44 PM rue_mohr: 340165F STATOR 240V
10:44 PM rue_mohr: hmm
10:44 PM rue_mohr: but they said thats the armature
10:44 PM rue_mohr: oh, they change both!
10:45 PM VanUnamed: see my point
10:45 PM VanUnamed: its confusing
10:45 PM rue_mohr: 360133F ARMATURE 240V
10:46 PM VanUnamed: change both is too pricey
10:46 PM rue_mohr: D is the 110V version
10:46 PM rue_mohr: it sort of makes sense seeing their electrical specs
10:46 PM rue_mohr: the 110V current is 200%, which is a pretty wild engineering range for a field current
10:47 PM rue_mohr: C,D,E,F are different votlages
10:48 PM VanUnamed: so i cant change one or the other, both have to be changed.
10:48 PM rue_mohr: it looks like it in this case
10:48 PM rue_mohr: if you just change the armature
10:48 PM rue_mohr: ...
10:49 PM VanUnamed: it burns.
10:49 PM rue_mohr: no
10:49 PM rue_mohr: it would have a low-end torque drop
10:50 PM rue_mohr: the 220V armature doesn't develop as much amps/torque as the 120V
10:50 PM rue_mohr: half
10:50 PM VanUnamed: so, i need changing both
10:50 PM VanUnamed: ughhhh
10:50 PM rue_mohr: the unloaded speed would be the same
10:50 PM VanUnamed: that transfomer is heavy as rocks
10:50 PM rue_mohr: yup
10:50 PM VanUnamed: and i need the drill outside to bust those big blocks of coal
10:50 PM rue_mohr: isn't that a fire hazard?
10:51 PM VanUnamed: how?
10:51 PM VanUnamed: 39% is moisture
10:51 PM rue_mohr: we dont have coal out here, but chatgpt says using a hammer drill on coal could ignite it, so you should be careful
10:52 PM VanUnamed: you are now messing with me arent you
10:52 PM VanUnamed: LOL
10:52 PM VanUnamed: to prove me chatgpt can be wrong
10:52 PM VanUnamed: wanna see pressure vessel welds grade? lol
10:52 PM VanUnamed: https://ibb.co/20m7hK81
10:53 PM VanUnamed: https://ibb.co/vxYdZbKM
10:59 PM rue_mohr: no fair, you cleaned the metal first
11:00 PM rue_mohr: do it with some old car batteries and coat hangers, then call me :]
11:00 PM VanUnamed: chatgpt says to do a root pass then a cap pass with 7018
11:00 PM VanUnamed: meaning, properly baked, 7018s
11:01 PM VanUnamed: what did you do, welded with a car battery? Lol
11:01 PM rue_mohr: I want to try it one day
11:01 PM rue_mohr: but I just adjust the current for the condition of the metal and dont usually clean it
11:02 PM VanUnamed: lol
11:02 PM rue_mohr: gpt WAS right about something that surprised me
11:02 PM VanUnamed: what?
11:02 PM rue_mohr: me:"Do you know the name of the song used to represent industry and production in looney toons cartoons?"
11:03 PM rue_mohr: and it got it
11:03 PM rue_mohr: "Powerhouse" by Raymond Scott.
11:03 PM rue_mohr: I'm not sure how it knew
11:21 PM rue_mohr: seems they changed up tho
11:37 PM rue_mohr: arg damnit
11:37 PM rue_mohr: thought I'd treat myself and bought 3 cans of refried black beans
11:38 PM rue_mohr: but soeone mixed the feaking shelf and 2 of the cans I got are freaking pinto beans
11:38 PM rue_mohr: and I opened one without noticing
11:38 PM rue_mohr: freaking stupid pinto beans
11:38 PM rue_mohr: hate them