// #eevblog — 2026-07-19
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
00:08:03 <arch> Kuschelpony, or possibly T3sl4, so my old synchronous generator with self excited brushless winding using a capacitor excitation system, is making 0V right now. the AC rated capacitor is busted and i can't get the capacitance rating from the housing. what would be the implications of using: a. oversized AC capacitor (say 100uF); b. undersized AC capacitor (say 4.7uF)? i assume bigger is better to a certain point?
00:08:22 <arch> https://cr4.globalspec.com/thread/43517/Capacitor-Excited-Generators
00:08:22 <EEVBot> [url] GlobalSpec | cr4.globalspec.com
00:08:36 <Kuschelpony> Hello arch
00:08:40 <arch> hi
00:09:23 <Kuschelpony> i expect that with a too small capacitir the excitation wont start, while a too large capacitor would lead to too high current and overheat the windings
00:09:49 <T3sl4> is that straight in parallel with the other stator windings or
00:09:54 <T3sl4> i mean, wound in the same places
00:10:38 <T3sl4> if it's phase shifted, maybe it could be other values, but if it's in the same place i'm thinking it acts like an induction motor in reverse, i.e. you need more reactive current than load current (roughly speaking)
00:10:40 <arch> honestly, i have no idea. it's a very very old generator. what i do know is the two exciting windings that went to a capacitor, are coming out of the inner assembly on their own
00:11:10 <arch> the other power windings, are hooked up to a "lug holder" plastic looking thing with 6 wires on it
00:11:52 <arch> see i confused myself yesterday when i was looking for the brush ring, because my other old generator uses brushes and slip rings for exciter winding
00:12:15 <arch> that's when i found out about this type of technology
00:13:03 <arch> well in any case, it can't hurt with too small an AC capacitor, so let me go find an old microwave oven capacitor, think that's like 2.2uF or something, and test if it outputs voltage
00:13:43 <arch> i might also have some scavenged air conditioner motor start capacitor too, those are 5uF or so
00:14:09 <arch> the original capacitor was rather large, like the size of a redbull can
00:15:34 <Kuschelpony> t3, these generators are a tricky hack, where the excitation works in some way like an asynchronous induction generator but then leading to iron saturation in the rotor acting as the poles of an synchronous generator
00:36:28 <arch> i just did a continuity test between the two separate wires (for the capacitor excitation), and to all the separate power and neutral wires to the lug holder mount, and there is no continuity. so yes, im pretty confident those two are solely for the capacitor. i additionally measured the resistance of the capacitor exciter winding and it's 3.5 ohms
00:42:46 <arch> the power windings are much much lower resistance. so i measured between live and neutral and saw 0.8 ohms (actually less im sure; multimeter leads are long)
00:47:22 <Kuschelpony> the resonant winding might be designed for 200 to 250V to need much smaller capacitors
00:55:33 <T3sl4> cool, so a rotating ferroresonant transformer
00:58:25 <arch> nice website: https://onan.xmsi.net/
00:58:26 <EEVBot> [url] Index of / | onan.xmsi.net
00:58:54 <arch> go to the root domain for 1990s nostalgia overload
00:59:27 <arch> so refreshing for pages to load instantly instead of 623MBs of dogshit unoptimized javascript frameworks
01:00:09 <arch> once the internet was commercialized, it all went to shits
01:02:52 <Kuschelpony> hmmm, if we would liveclose enough i would bring a box of capacitors and we try out which capacitance we need
01:04:08 <arch> want me to ship the generator to you via ship? lol
01:22:54 <arch> YEET. found a suitable cap from my stash of scrap. 10uF-com-35uF air conditioner capacitor rated 250VAC
01:23:10 <arch> now once it stops raining, im going to test it out with the 10uF setting first, then the 35uF setting
01:25:03 <arch> oh, and i guess ~8uF (tested between fan-herm terminals; series caps internally)
01:25:56 <Kuschelpony> yes, DO IT
01:26:21 * arch proceeds only to get a violent capacitor explosion that maims him
02:09:17 <rc-garage> YAAAY!
03:29:33 * electrohead films
03:29:51 * electrohead shoves a ground rod into arch, pokes rc-garage in the eye, blames T3sl4 and Kuschelpony
03:33:16 * T3sl4 smotes electrohead with arch
03:40:16 * arch reduces T3sl4's opamp bandwidth
03:40:36 <T3sl4> D:
03:42:37 <arch> hmm, leeks taste good with stir fried instant noodles
03:42:53 <arch> https://leekspin.co/
03:42:54 <EEVBot> [url] LEEKSPIN.CO | leekspin.co
03:53:08 <electrohead> just needs the "you spin me right round" song playing in the background lol
04:03:31 <rc-garage> https://www.youtube.com/shorts/arZyIdFntUA?feature=share
04:03:31 <EEVBot> [YouTube] This clever solution really works #GarageLife #SmartSolution #HandyTrick | 20s | Channel: Spider Mechanic | 14,335 views | 2026-07-17 - 15:00:28 UTC
05:01:17 Quit: Kuschelpony ([email protected]) Connection closed
05:43:39 <rc-garage> I like meat in my noodles. do you want me to post a link?
05:57:14 <arch> rc-garage, no thanks
05:58:03 <arch> rc-garage, im american, so i like a gun in my noodles: https://www.youtube.com/watch?v=1BIqhTqrrZA
05:58:04 <EEVBot> [YouTube] Making Gun Soup | Assassination Classroom | 17s | Channel: FweddyYT | 122,904 views | 2021-02-07 - 19:50:31 UTC
06:00:39 <rc-garage> sorry, I do not understand that southern accent. yes, i am guessing it is that, mixed with 12 or more generationg of inbreeding
06:01:09 <arch> \o/
06:01:10 <EEVBot> |
06:01:10 <EEVBot> [ ]
06:26:24 <MrMobodies> Finaly:
06:26:25 <MrMobodies> https://www.bbc.co.uk/news/articles/c5y08z25q8eo
06:26:26 <EEVBot> [url] Andy Burnham to scrap digital ID to focus on 'helping with cost of living' - BBC News | www.bbc.co.uk
06:26:44 <MrMobodies> So more more PRESSING ISSUES
06:40:34 <arch> so my power is out right now. i did get my firewall and modem running off backup power, but it would seem cable modem is dependent on the "substation" to work as well :|
06:51:29 <rc-garage> I have a ups sort of thing, I never hooked it up. I probably should
06:56:26 <electrohead> rc-garage: I reckon there's der sum corn up yonder
08:05:42 <rc-garage> poop corn
09:13:47 <MrMobodies> Very unusual weather
09:13:51 <MrMobodies> in the middle of Summer
09:17:18 <MrMobodies> https://i.postimg.cc/44026MGW/190726-temp.jpg
09:17:19 <MrMobodies> 12.8c
09:17:30 <MrMobodies> and it feels like a frigde outide
10:19:53 <MrMobodies> gone down to 11.9c
10:29:05 <flyback> we are talking on libera ##electronics how server psu's are built like tanks, aLL one voltage rail output, dirtt cheap and you can buy breakour boards cause people use them for miners and rc battery charging
10:29:59 <flyback> I am going to use one to convert the not so great capacitor brushless generator design output to dc then buffer to cap and invert to get smooth sine or square-sine output for electronics and led lights
10:30:16 <flyback> you guys should research them
10:30:23 <flyback> they are cheap and plentiful
10:30:47 <flyback> the only thing server psu's might not be good for is very sensitive fringe analog/rf projects
10:31:32 <flyback> also they have great safety when they finally shit themselves one day it will just turn off
10:31:42 <flyback> no spiking the load
11:03:50 * arch spikes flyback's drink
11:43:19 * electrohead places a load into arch's drink
11:43:22 <electrohead> wait
12:12:14 * arch hacks into electrohead's runescape account and pawns off his mithril scimitar for 100gp
12:29:01 * DogWomble formats the disk in electroheadś Commodore 1541 disk drive
12:59:06 Quit: steve30 ([email protected]) Quit: <Baljem> steve30: by the way, I had the most bizarre dream the other day that someone came in here and seriously flipped their shit over your quit message and why aren't the ops /doing/ something about it
15:37:11 Join: adsr ([email protected]) to #EEVblog
18:10:22 Join: spyda_ ([email protected]) to #EEVblog
18:13:19 Quit: spyda ([email protected]) Ping timeout: 2 minutes
18:14:26 Join: Kuschelpony ([email protected]) to #EEVblog
20:09:39 Join: steve30 ([email protected]) to #EEVblog
20:09:40 Mode: (by ChanOP) +o steve30
21:15:50 Join: watcher ([email protected]) to #EEVblog
21:27:25 Quit: watcher ([email protected]) Client exited
22:44:17 <electrohead> lol
22:44:24 <electrohead> arch: I never played that game, haha
23:00:04 <arch> electrohead, what about World of Warcraft, or Anarchy Online?
23:00:08 <arch> or Guild Wars
23:03:57 <rc-garage> guilt wars. that is a fun one
23:04:07 <electrohead> tried playing world of warcraft, lasted maybe five minutes and gave up
23:36:47 <arch> Kuschelpony, T3sl4 regarding that self excited capacitor generator yesterday: i think this is a good demonstration https://www.youtube.com/watch?v=OML8LjGegrQ
23:36:47 <EEVBot> [YouTube] Self excited induction generator (part 1) | 3m 21s | Channel: BTCInstrumentation | 75,677 views | 2014-04-29 - 15:43:10 UTC
23:37:21 <Kuschelpony> sorry, i cant watch videos
23:37:27 <rc-garage> arch, i think he still does not watch videos
23:38:03 <T3sl4> right, you can use an induction motor in reverse
23:38:18 <T3sl4> forwards, the current draw is always inductive, the real part varying with load
23:39:04 <T3sl4> if you have, i think, more than that amount of capacitive reactance, the amplitude grows rather than decays, and you get a generator (that can start spontaneously from residual magnetism in the steel, but if not maybe a jolt to get it going or whatever)
23:39:23 <T3sl4> well. less reactance. more as (capacitive) reactive current.
23:39:52 <T3sl4> but the frequency depends on load, as it always does
23:40:52 <Kuschelpony> its the same mechanism as a DC dynamo, just without brushes
23:40:53 <T3sl4> whereas with a sync machine, if it can get spontaneous (DC) magnetization, which i gather between winding resistance and the diode on your diagram, it would, then frequency and therefore amplitude (limited by saturation) will be stable with RPM
23:42:19 <Kuschelpony> yes
23:43:09 <T3sl4> i suppose it's made in such a way that the induction side runs the field winding? so the capacitor needs to be sized to run that as a load, and overcome whatever reactance is left. you need the V/I rating of that winding, then
23:43:25 <T3sl4> should be safe to use increasing values until it works (starts quickly?)
23:44:46 <arch> i found my next binge watching channel. very interesting experiments: https://www.youtube.com/watch?v=RGPCIypib5Q
23:44:46 <EEVBot> [YouTube] Synchronizing AC generators -- Part 1 (introduction and sync lamps) | 5m 5s | Channel: BTCInstrumentation | 258,017 views | 2014-06-05 - 18:24:45 UTC
23:45:39 <T3sl4> i find it peculiar that he's got safety glasses on but long sleeves around open belts
23:47:07 <rc-garage> some people just wear safety glasses when they get up in the morning. it is a thing
23:47:20 <arch> lol
23:49:55 <Kuschelpony> https://files.mastodon.social/media_attachments/files/116/946/858/250/801/268/original/5904368cbe58803c.png
23:50:11 <rc-garage> which is fine, I guess. I would like more pastel colors on his shirt.
23:56:46 <arch> "Disney: Spin" now in russian machine shops near you
Search this day's buffer: