Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: john larkin Newsgroups: sci.electronics.design Subject: Re: more X-rays Silvertel PoE Supply Date: Wed, 02 Oct 2024 15:39:31 -0700 Organization: A noiseless patient Spider Lines: 56 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Thu, 03 Oct 2024 00:38:18 +0200 (CEST) Injection-Info: dont-email.me; posting-host="a7923f72a56a5feb4e75819060cd2c1e"; logging-data="3592467"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+N8jELlbJpqS8BHV8zEOp7" User-Agent: ForteAgent/8.00.32.1272 Cancel-Lock: sha1:QAexorU5wdC9C304IMNSLvtwVFM= Bytes: 3561 On Wed, 2 Oct 2024 17:00:52 -0400, "Edward Rawde" wrote: >"john larkin" wrote in message news:kqbrfjhrd5oto8ud8vm0395p6oo8eipige@4ax.com... >> On Wed, 2 Oct 2024 11:46:21 -0400, "Edward Rawde" >> wrote: >> >>>"john larkin" wrote in message news:v6mqfjd93ib6q8j7d7ontsaouidieh5b2u@4ax.com... >>>> On Wed, 02 Oct 2024 06:22:43 GMT, Jan Panteltje >>>> wrote: >>>> >>>>>On a sunny day (Tue, 01 Oct 2024 14:16:09 -0700) it happened john larkin >>>>> wrote in : >>>>> >>>>>> >>>>>>https://www.dropbox.com/scl/fo/s6wfz2xtdyd6tv32tq3fp/AET6J4oF84HG2hJMeST6F-E?rlkey=acyvuv4z0h2kg0x97azbed8uo&dl=0 >>>>> >>>>>Cannot make out much from those x-rays, pictures are better... >>>>>you can probably see the traces just like that? >>>> >>>> The x-rays are fun, but are admittedly more useful for an opaque >>>> potted module or an IC or discrete semi. I can prety well trace the >>>> Silvertel without them. >>>> >>>> I have a gigantic scary Carribean guy who does the xrays and I wanted >>>> an excuse for taking him to lunch, which turned into an interesting >>>> hike around The Bernal Cut. He trashed the xray system software, and >>>> had to rebuild it, and now it can do movies, which is great. >>>> >>>> I'd like to have some products that can be powered by PoE or a wart, >>>> and may want to put two 24-volt PoE supplies in series to get 48, so I >>>> need to understand how they work. The xrays just help a bit. >>> >>>If Ag9900 just works then why would you care how? >> >> Can I overpower it with a wart? Does that need another diode? > >Maybe. See other discussion in this thread. > >> >> Can I run two 24v Silvertels in series to get 48? > >I don't see why not since the data sheet says isolated. >It shouldn't be hard to verify that. Batteries are isolated, but a series string can destroy one cell by back-biasing it. Some power supplies will latch up, or not start up, in series with others. Lots of suplies won't start (and may fail) if their input is pulled negative. As the number of items in a design increases, the probability of some stupid error approaches unity. It's usually time efficient to be super careful, as opposed to spinning a few PCB revs.