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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: more X-rays  Silvertel PoE Supply
Date: Thu, 03 Oct 2024 09:04:55 -0700
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On Thu, 03 Oct 2024 06:38:41 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

>On a sunny day (Wed, 02 Oct 2024 15:39:31 -0700) it happened john larkin
><jl@glen--canyon.com> wrote in <kgirfj1614cfkvknad7dl2igqcb2qi5tq7@4ax.com>:
>
>>On Wed, 2 Oct 2024 17:00:52 -0400, "Edward Rawde"
>><invalid@invalid.invalid> wrote:
>>
>>>"john larkin" <jl@glen--canyon.com> wrote in message news:kqbrfjhrd5oto8ud8vm0395p6oo8eipige@4ax.com...
>>>> On Wed, 2 Oct 2024 11:46:21 -0400, "Edward Rawde"
>>>> <invalid@invalid.invalid> wrote:
>>>>
>>>>>"john larkin" <JL@gct.com> wrote in message news:v6mqfjd93ib6q8j7d7ontsaouidieh5b2u@4ax.com...
>>>>>> On Wed, 02 Oct 2024 06:22:43 GMT, Jan Panteltje <alien@comet.invalid>
>>>>>> wrote:
>>>>>>
>>>>>>>On a sunny day (Tue, 01 Oct 2024 14:16:09 -0700) it happened john larkin
>>>>>>><jl@glen--canyon.com> wrote in <tipofjdtie76lbtd7lc2ger5uo7sglq3p5@4ax.com>:
>>>>>>>
>>>>>>>>
>>>>>>>>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.
>
>Why always some XXXchip?
>What's wrong with designing with normal components and adding a known micro?

That's exactly what I'm doing. Stock parts and an RP2040 CPU chip.

There are *so many* Raspberry Pi kids out there! 

Now if I could build the hardware part of the product with Legos...