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1
Thanks.  Yeah,  I saw those -  using https and talking to a web server.  I was wondering if you could share any detail about this mechanism.  How will you authenticate with the server and/or have the server authenticate with the device?  Other than encrypting updates will you do any additional authentication or validation of them?  I guess you'll have storage for at least 2 firmware images and a roll-back mechanism for failed updates.  Any other specific security related functionality?

I ask because I have a similar project for a client who a) doesn't want to spend money on security and b) has an existing web infrastructure to which he is adding the device I am working on for him so I have to follow an existing web API.  It's easy to say stuff like, "well this device will be turned off most of the time" and there's only going to be hundreds or thousands of them in the field so no-one will care so we don't have to worry about the attacks zilp has detailed but I'm still nervous, if only for my reputation, because I know how this client will react if the device is ever compromised (he'll blame everyone but himself).

One way I've described earlier:

    DEVICE  <---- Websocket over TLS --->   BACKEND <---- HTTPS ----->  OPERATOR

The backed would terminate connections from devices. Devices can be authenticated either:
  a) using TLS certificates - so-called two-way TLS. That's the way how AWS IoT authenticates devices
  b) using auth tokens, or password strings. Both device and backend would store those, and device can send either a token ot its hash in the WS handshake

For users / administrators, the backed would provide a usual HTTP REST API. Usual auth schemas are user/pass login, or Oauth.

Now, OPERATOR can authenticate with BACKEND and send REST API calls to list devices, see their status, change their config, update them, etc.
2
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3
Stay brite 8 has a tensile of 15,000 psi. Its just silver and tin.

Citation needed.

Horse mouth says 10.6 KSI,
https://ch-delivery.lincolnelectric.com/api/public/content/e521e75f45b741e58940da1988c2976d?v=a156575a
but again I'm dubious about method or how it's actually measured (no standard cited, and not that ASTM standards are generally publicly available anyway).

Indium Corp seems to suggest closer to 7,
https://www.matweb.com/search/DataSheet.aspx?MatGUID=19662ece2a4a4bb2bbe7aa522f916185
though the alloy is slightly different, but again, no mention of method.

Tim
4
So, a few suspicious waveforms...

The nibble select on the input mux:



This is somewhat "squashed"? The dashed line on the top is the 5V level for reference, and the center is 0V.
Or is that normal for a discrete logic circuit to do that when the signal is "inhibited" e.g. by not being let through an AND gate? I've never worked with discrete logic closely before.

One of the 2114 SRAM output lines also look kinda weird:



The rising edges are somewhat slow it seems?

This does not look like real logic signal to me entirely  :-//



If anyone has more experience with discrete logic, your input is much appreciated!
5
Beginners / Re: Transistorized DC amplifier
« Last post by Picuino on Today at 06:12:46 am »
Yes.
6
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www.2pcbtechnology.com
7
Repair / Re: Longwei 3060 PS Dead
« Last post by metrologist on Today at 05:51:33 am »
I measured the fet, outside pins are 0.691, inside are 0.559 and 2.8 or OL. Opposite polarity is 2.8 or OL.

I cannot get a reading on cap in circuit, should be 47uf if I read it correctly. Resistor looks and reads like 110k.

I tried to scope out some pins on and around uc3842, with ground to chassis, but first verified 0 ohms to neg output and no ac on dc output terminals. I probed -180V, +/-180 on large caps.

Then I saw the fan kicked a turn, decimals on the displays. I disconnected and cycled power and saw 666 on the display.  :-DD

——-

8
General Technical Chat / Re: Youtube "how to" videos are mostly useless
« Last post by elektryk on Today at 05:43:32 am »
some more useless I have seen on youtube

jump starting anything with a 9 volt battery
soldering through hole components together without any pcb or symmetric diagram. as in extreme dead bug soldering.
working with 240 volts AC, as if it was safe 12 volts DC. as in dangerous wiring
inserting anything but a drill bit into a drill chuck.
mixing food with anything.
using hot glue to hold anything. fasten a motor without bolts.

1000 DEGREE KNIFE VS
(but some of such videos are interesting indeed)

Pakistani mechanics and how they repir big equipment

I like to watch them too, its quite entertaining.
9
And  suggestions like "why you don't want auto range" is like when a guy asks - "Please help me with the directions to the post office?" and instead of directions he gets - "we need to know what is your problem, maybe a pub or strip club is the place where you should go?" :D

Suppose the nearest Post Office is 100 miles away and is closed anyway, but the local store has a mail drop and such.  Before answering your question, wouldn't it be helpful to know if you just wanted to mail a letter or buy a stamp versus wanting to apply for a passport? 
10
Test Equipment / Re: Fluke accuracy ±(2%+2) - What means the +2?
« Last post by boggis the cat on Today at 05:37:18 am »
A "fun" fact: I have seen a meter where the +number specification was worse than the % specification, even at full scale. I believe that this is sort of misleading. It was a ACV specification where the % was very good, but when adding the +number it was at best average (I do not remember the name of the meter).
That isn't uncommon for the very cheap instruments.  Sometimes you will see a change from +/- counts to +/- a value in order to try to be extra squirrelly.  Higher priced instruments will occasionally have this crop up in the margins, where they are presenting accuracy data (sometimes only 'typical') for end users that insist on using equipment beyond its real capabilities.

Beware of cut-down specification comparisons that only quote the % values (or other ratio).

Then there is the entire discussion over how realistic some accuracy claims may be.  (In general, the bigger name brands even amongst the cheap offerings are a lot more reliable.  No-name stuff is a bit of a lottery.)
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