Recent Posts

1

Test Equipment / Re: Siglent Bench DMMs SDM3065X, SDM3055 and SDM3045X

« Last post by mawyatt on Today at 12:32:12 pm »

Here's 7 hours at 10V, 10PLC. Reminder that it's a aliexpress AD584 ref. 😉





What PLC is your meter set to?

It is 10PLC and a sliding 1hr window. Here's result just taken with SDM and DMM6500, both similar settings.

Points too SDM LM399 internal reference!!

Best

2

Test Equipment / Re: Keysight 34450A Help

« Last post by Eraldo on Today at 12:31:18 pm »

Honestly speaking, as long as the devicevis within spec with the other ranges i see no reason to try and fix that specific range which you will rarely, if not ever use at that high of a frequency (assuming it's within spec for lower frequencies)

Also i saw that you have been asking this question in other parts of the forum and duplicate posting is frowned upon. 

3

General Technical Chat / How George Hotz Hack iPhone (the Hillary behind it?)

« Last post by Mechatrommer on Today at 12:30:18 pm »

while killing time, it usually started with some random youtube on my channel wall... what was meant only took couple of minutes can turn into couple of hours it started with youtube title "Sony Attacked Anonymous And Immediately Regretted it" YT id: 66A4zcJaPLk... and then came the name George Hotz, clueless about who he is (yeah you can say i'm living in a cave), so the google investigation started, after reading some links i thought wow this guy could be the 2nd Kevin Mitnick! so then trying to google how this "geniusity", his 1st hack that made his famous is exactly this thread's topic and what i typed in google hunt (excluding whats inside the bracket)... so the politics behind it revealed...

Reminder that geohot wasn't the first person to jailbreak an iPhone

if its true, then its quite hilarious as equally quite typical (we usually rely on the works of others) except he's quite lucky he started too young than most of us... probably his father bought him a good PC and he was living in a conducive hacking environment.

another thing is OpenPilot the only post mentioning his name in this forum is this https://www.eevblog.com/forum/beginners/non-reprogrammable-gate-array-as-aposed-to-field-reprogrammable-gate-array/msg3914087/#msg3914087 (this thread will be the second i guess) so his name is credited to this great self driving software, but OpenPilot is based on OpenAI isnt it which is created by a bunch of pHD holders in IT, so not so much wonder there, you and i  can probably make some script on top of OpenAI and create something wonderful too right? given enough time and courage...

with all this mumbling, its not actually my point.. my point actually is.. then i look up in google if there is any picture of his room probably i can get some idea how he worked on hacking the iphone, i cant get any from google, but it turned out the picture is available (although he is a little bit older in the picture) in the first video i mentioned above with the id (minute 4:51)... i thought WHAT?! NO OSCILLOSCOPE?! how easy it is to hack iphone IC's communication protocol without a scope? just some fancy boxes and monitor, and some retro/vintage AC/fan unit at behind and whats that next to it? a nitrogen tank? probably the real persons who actually did the real work on jailbreaking the iphone, ps3 or samsung android are those the unsung heroes living under the rock with some power line wires poking in... ymmv.



so here it is, few hours wasted.... cheers.

4

Test Equipment / Re: Vevor SDS1104 for first oscilloscope?

« Last post by MadFlower on Today at 12:28:11 pm »

Some Vevor items are well made , are an extremely very good value and perform very well . Other items are crudely made and  have multiple defects . Fortunately I used PayPal when ordering directly from their USA distributor recently . Even after I submitted a claim for an obviously  defective and unusable tool they made every possible effort to avoid a refund .

Purchasing it from Amazon with their excellent return policy is advised

I guess I will find out. I used paypal for that reason. The 150 bucks was actually out of my budget and it is a lot more scope then I currently need. however having a scip gives me a logic analyzer so I will find a use.  I think Vevor in general just rebadges other products. However, there is some variance in products with the same model numbers. I just haven't seen other say owon or siglent knockoffs like you do for say soldering stations.

I also sent a message asking them about their compatibility because they mention upgrades in their description but offer none for sale, so I asked if you could use the siglent or owon upgrades.  I also asked for the compatibility of the SCIP commands, or a documented list of them.

We will see if they answer.

5

Beginners / Re: Put LC filter before or after LDO?

« Last post by Manul on Today at 12:27:39 pm »

I usually power my own circuits from USB 5V, and that has a limit of maximum 10µF capacitance; so, I tend to use regulators that tolerate sufficient capacitance on the output to give me stable voltages.  For ADCs and similar having their own supplies, I like to use a ferrite bead to absorb/reflect the high-frequency noise (say, above 10 MHz).

So do mean for a typical +5V rail of a USB outlet, some spec says 10uF is the max capacitive load at some frequency? Surely I've seen much bigger caps on the input of USB devices.

Yes, there is such spec for maximum capacitance. Frequency does not play here. Capacitance ceiling is meant to limit inrush current. There are a couple of reasons why such spec exists.

USB is designed to be hot plugged, so a high (and long duration) inrush current may cause momentary voltage dip on the entire bus, thus resetting or otherwise affecting other connected devices. Minimum bus voltage by spec is I believe 4.75V, so there should be no dips below that during hot plugging. Even one step further - it is possible that a high inrush may simply trip bus overcurrent protection.

Second reason is durability of connectors. Type A might seem like a fairly robust one, but mini B and micro B are real tiny. Those pins are certainly not designed with sparking in mind and will deteriorate quickly during hot plugging if inrush current is high.

Similar thing exists with boards meant for hot swapping, for instance, CompactPCI boards. They have hot swap controllers which control power rail inrush and usually also precharge I/O lines, so there is less glitch when you insert a board into a powered, working system.

Sure we live in a free world and rules can be broken, but it usually comes with consequencies.

6

General Technical Chat / Re: What ICs are used in this rocket?

« Last post by Gyro on Today at 12:15:11 pm »

For anyone who is curious as to the answer rather than just with Faringdon being a troll  .

Radiation-hardened FPGAs and microcontrollers/SoCs most likely if they are "old space". 

Or they could be using consumer devices with higher tolerance to single event upsets which is the SpaceX ("new space") approach - reasonably normal computers (they use x86 Intel processors of one kind or another) but with much redundancy and self-checking. See here:  https://space.stackexchange.com/questions/9243/what-computer-and-software-is-used-by-the-falcon-9

That thread seems to imply that radiation hardened ICs and large scale redundancy are alternatives, but that's not really true. The two have usually been combined to achieve acceptable results.

The OP already has a thread on hardened semiconductors, discrete vs IC etc... https://www.eevblog.com/forum/renewable-energy/discrete-smps-have-any-advantages/

Quite why he wants to know the manufacturers of the silicon in this particular rocket is beyond me. Ed: Whether they use Vicor power modules, even more so.

7

Test Equipment / MSO5102D Block...

« Last post by zol on Today at 12:12:09 pm »

Hello to all...!

After a bad firmware upgrade , my MSO5102D is stuck at the beguinning start cycle : at switch ON appears the blue screen with strips of different colors ( as usual ) but suddenly turns black with some little dots at top and, after some seconds, start again with the blue screen ( in an eternal loop...).
I have attached a serial-usb converter inside the circuit internal ( after some intense search info ) and I have the initial boot log (attached to this message) (I guess is well attached...)
The serial number is : T 1G/012 009551
The soft version is : 2.07.1 ( 130321.0 )
The hard version is : 10070x555583e9

Of course I don't have any backup of the original Filesystem...!!
I guess some upgrade of a correct image or some important files are needed to turn the MSO to life....

Any help is well received ....!
...and thanks in advance too...!!!

Zol

8

Embedded Computing / Re: Graphical Calculators running basic

« Last post by DiTBho on Today at 12:10:08 pm »

GW-BASIC like? -> SHARP PC-E500

9

General Technical Chat / Is there a meaning to colors on a transitor?

« Last post by RAPo on Today at 12:06:47 pm »

I've got a whole collection of (unclassified) transistors.
I'll know that a dot on it can mean it is a matched pair.

But I also have transistors with several colours.


Do these colours have a meaning?

10

Projects, Designs, and Technical Stuff / Re: Emergency stop for runaway large DC motor

« Last post by ifonlyeverything on Today at 12:05:38 pm »

I'm not really understanding how or why it's dangerous for the motor to disconnect from the load. Motor will run fine with no load. Operator won't be harmed unless it's an external belt drive with no guards?