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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: more X-rays Silvertel PoE Supply
Date: Thu, 3 Oct 2024 22:37:10 -0000 (UTC)
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john larkin <JL@gct.com> wrote:
> 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...
> 
> 
> 

Over the past 30-odd years, various people have come up with the idea of
using legos for optomechanics. 

Then they go away for a summer weekend and return to find that their gizmos
are completely misaligned due to stress relaxation in the plastic. 

Cheers 

Phil Hobbs 

-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics