// #eevblog — 2025-10-03
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00:02:31 <K> oy watch it
00:16:58 <electrohead> watch what you say now
00:31:17 <arch> "you better back the fuck up before you get smacked the fuck up" - 2pac
00:32:20 <arch> also, related any time 2pac is mentioned: https://pbs.twimg.com/media/FHbJ5ZQWQAYU8TS.jpg @T3sl4
00:32:52 <T3sl4> you say that but i am literally the watcher rn
00:32:58 <arch> now the opposite happens whenever i ask cgpt some EE questions and it makes up blatant lies
00:33:10 <arch> fuck you bitch, why you always got something positive to say
00:33:59 * Vampera hugs arch
00:34:00 <Vampera> <3
00:34:15 <Vampera> I'd bite you for your blood, but I'm worried it might be mixed with ATF
00:34:50 <arch> lol
00:35:00 <T3sl4> ew, automatic
00:35:35 * arch slathers T3sl4 in stinky 75w-140 gear oil
00:35:43 <T3sl4> u stinky
00:35:47 <arch> no u
00:35:49 * Vampera chomps on T3sl4
00:35:56 * T3sl4 moans
00:36:00 * Vampera moans harder
00:39:59 <arch> hm, can you make a current mode pwm controller using just 7400 logic ics, and how easy or difficult would it be
00:42:22 <T3sl4> easy, i guess?
00:42:30 <T3sl4> https://www.seventransistorlabs.com/DC-DC_RE/index.html this thing comes to mind
00:42:30 <EEVBot> [url] Reverse Engineering: 5V Converter | Seven Transistor Labs, LLC | www.seventransistorlabs.com
00:45:46 <T3sl4> prob easy enough to use a 74LS123 or whatever as the timer/comparator
00:48:53 <arch> oo
00:54:46 Quit: watcher ([email protected]) Quit: KVIrc 5.2.6 Quasar http://www.kvirc.net/
01:06:03 * electrohead shunts T3sl4
01:07:22 * T3sl4 dumps a load on electrohead
01:08:30 <Agripa3> Pft, you can do with with transistors.
01:09:09 <Agripa3> Early switching regulators did not use any ICs.
01:34:12 <T3sl4> yeah, but doing it with few transistors is easy. doing it with large numbers of transistors, already fixed into certain bespoke circuits, is a lot harder
01:35:33 <Agripa3> I have an example schematic here somewhere ...
01:37:44 <Agripa3> Not sure if this counts as an LLC regulator, but it is close, https://i.imgur.com/h2pFMY6.jpeg
01:38:05 <Agripa3> Tektronix later made an IC to replace the discrete controller part.
01:39:26 <Agripa3> That design inspired Steve Wozniak to design the switching supply for the Apple 2.
01:41:17 <Agripa3> T3sl4, I keep coming up against needing a regulated low noise floating supply. Thinking of using a custom transformer and driving it with a variable amplitude sine wave, or a resonate Royer converter, to produce floating +/-15, +/-200, whatever.
01:42:03 <Agripa3> Wire two high frequency transformer in series to provide isolation,and multiple transformers could be on the output side to provide different tracking voltage outputs.
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02:06:16 <flyback> whatever you do Agripa3 don't forget a crowbar circuit on your psuy
02:07:00 <Agripa3> Probably not necessary. The primary side has limited voltage compliance, and the transformer turns ratios are fixed.
02:07:53 <Agripa3> I guess I would need to check that with a resonate Royer configuration.
02:08:44 <Agripa3> Voltage regulation in this case is primary side only.
02:09:23 <Agripa3> I was thinking about it last night because now I have two different projects which require an isolated low noise supply which may be high voltage.
02:09:54 <flyback> heh
02:10:02 <flyback> glad you guys understand that stuff
02:10:05 <flyback> I only know a litle
02:10:38 <flyback> wish I could afford a cheap isolation transformer
02:10:57 <Agripa3> Wire two of the same normal transformers back to back. That is what I do.
02:12:42 <Agripa3> Some power transformers, like flat-packs, may have a dual primary which can be wired for 120 or 240. That kind of transformer by itself can be used as a 120 volt isolation transformer.
02:13:01 <flyback> yeah I thought about doing that
02:13:16 <flyback> I have some 12v to 120 ups transformers
02:13:17 <Agripa3> They are safe to use that way because the primaries are isolated on separate sections of the bobbin.
02:13:37 <flyback> they appear not to be switching type
02:13:37 <Agripa3> UPS transformers tend to have a high magnetizing current, so not so suitable.
02:13:45 <flyback> 3+2 wires out of them
02:13:56 <flyback> it was from apc's literal first model ups
02:14:02 <flyback> so I think they are normal mains transformers
02:14:15 <Agripa3> Although they usually use the same transformer for stepping up the UPS output, and charging the battery, so they could work.
02:14:26 <Agripa3> Yes, they are. They should work.
02:14:46 <Agripa3> I had an APC like that, and also a big Cyberpower one which ate batteries.
02:17:55 <flyback> the other thing that sorta gives them away as mains freq transformers is their size
02:18:03 <flyback> fist sized and probably 10 lbs
02:20:07 <Agripa3> yep
02:21:47 <flyback> I still have one of apc's first model back ups 200w
02:21:49 <flyback> it has no brain
02:22:02 <flyback> except a primitive one made from 4000 series logic
02:22:08 <flyback> no mcu
02:34:06 <arch> thats cool
03:22:43 <flyback> well no it's dumb as a post, and only simple signalling to the pc
03:22:50 <flyback> but it was their first design
03:22:51 <flyback> so ...
03:23:22 <flyback> although simple signalling is nice to hookup a ups to something that can't do normal serial or usb comms
03:23:55 <flyback> but can be triggered to shutdown by a serial pin going high or low on battery low signal
03:24:20 <flyback> arduino etc
03:25:24 <rc-garage> really dumb things, can be cool.
03:27:07 <flyback> insterestingly a lot of high end enterprise ups's have "contact closure" relay pins
03:27:20 <flyback> to implement your own wire signalling for stuff that can't have ups software
03:27:26 <flyback> such as some weird mainframe etc
03:27:37 <flyback> so you can hack together your own solution to send a low battery shutdown signal
03:28:19 <Agripa3> I was impressed when Windows 10 automatically added a battery charge indicator when I plugged in the USB cable to my newer UPS.
03:28:32 <flyback> yeah thats existed for a long time
03:28:36 <flyback> back to xp even afaik
03:28:39 <Agripa3> Never worked for me before.
03:28:49 <Agripa3> Treats the UPS as sort of a laptop system.
03:28:53 <flyback> yeah
03:29:04 <flyback> mine are all startong to fail and I need a job before I get battrries
03:29:06 <flyback> oh well
03:29:09 <flyback> mabye xmas money
03:29:17 <Agripa3> I just have a cheap one for my other systems, and an old 700 watt online ups for my workstation.
03:29:45 <Agripa3> Home Depot seems to have the best deal on 12V 7AH batteries, and free delivery.
03:30:29 <flyback> yeah I get can 12@8 from tractor supply no shipping cos like $34 if I let them deliver to the local store
03:30:33 <flyback> which is only 15 mins away
03:30:55 <flyback> I don't think the home depot sla's are high current and meant only for exit signs
03:31:04 <flyback> so they mauy only last a few cycles
03:31:08 <flyback> bbl, meeting
03:51:59 Quit: Lord_of_nothing ([email protected]) Ping timeout: 2 minutes
03:53:01 Join: Lord_of_nothing ([email protected]) to #EEVblog
05:57:11 Quit: pa1983 ([email protected]) Connection closed
05:58:54 Join: pa1983 ([email protected]) to #EEVblog
06:36:52 * arch joins flyback in the big beautiful latinas meeting
07:07:59 Quit: Jens ([email protected]) Quit:
07:08:04 Join: Jens ([email protected]) to #EEVblog
08:10:41 * electrohead joins too
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