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Part 2:


Is it only my impression, or did the specimen got worse from the previous video? It feels like the value went even higher.
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Beginners / Re: Signal generator question
« Last post by BennoG on Today at 06:26:18 am »
A function generator can drive 1 small led, if you want to drive more leds you need power amplification (mosfet / transistor)
So that would be a very expensive led driver for a single led.
Most if not all FG's are build to deliver only a couple of mA.  A single led takes about 10-20 mA a COB can take up to 3000 mA

Benno
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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.
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5
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
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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!
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Beginners / Re: Transistorized DC amplifier
« Last post by Picuino on Today at 06:12:46 am »
Yes.
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www.2pcbtechnology.com
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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

——-

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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.
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