Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Design of white noise generator for bathroom??

« Last post by Gyro on Today at 09:06:35 am »

Really install just any audio system that can play digital audio at a couple Watts, you'll find hundreds of ready-made files with "white noise" content (which is not white, but we know what this is about), pick the one that your wife likes best, and call it a day. Designing something from scratch for this is not worth it.

White (or better, pink) noise seems to be a very poor use of such technology. Why not something more relaxing like waves crashing on a beach or a trickling stream! There must be much better masking sounds than a 'constant' amplitude noise.

2

Test Equipment / Re: Hacking the Rigol DHO800/900 Scope

« Last post by Fungus on Today at 09:06:07 am »

In my opinion this clearly points to a firmware glitch

EVERYTHING is a firmware glitch to some people.

not doing the skew compensation properly.

More likely they're not even trying to because it's a fools errand.

Connect up the probes, compensate the skew manually, take the measurements. Don't fiddle around with the setup once you've got it dialed in.

3

Beginners / Re: Motor driver won't talk to me :(

« Last post by Psi on Today at 09:02:05 am »

What voltage is on these pins of the DRV8434

DVDD
VCP
VREF

4

Test Equipment / Re: Are 'premium' scope brands still justified?

« Last post by nctnico on Today at 09:00:42 am »

Still, one of the rather unique features of the Keysight oscilloscopes is that these can decode across segments. When recording a bunch of segments, the decode table shows data from all segments (with timestamps ofcourse!) in one so you can hop through the various segments with ease. On other oscilloscopes I've seen/used so far you'll need to go through each segment and look at the decoded data for that specific segment; there is typically not an easy way to aggregate all decoded data.

5

Test Equipment / Re: Hacking the Rigol DHO800/900 Scope

« Last post by Fungus on Today at 08:59:51 am »

Question: Are the probes properly compensated?

Please take another careful look at Slavius' reply #2605. He did manually compensate the skew carefully -- but then it's off again when he enables more channels.

Probe compensation uses the compensation signal on the front panel.

6

Beginners / Re: probes x1 or x10

« Last post by tggzzz on Today at 08:58:32 am »

I know, zombies... I am in exactly this situation, first cro (dso2d10 converted to 15) and I am usually playing with arduino or esp32 or pic etc and have wondered if I should be using 1x or 10x setting on my probes. After reading all the posts I am still left without a definitive answer. I understand using 10x offers a reduced loading on the circuit, but with logic levels of 5v or 3v, unless i am probing around the crystal, but rather uart, spi etc, does it really matter?
 
I notice spurious noise that isn't related to the actual signal that can only be reduced in 10x if I switch to HR mode (and lose sample depth) and also enable 20mhz filter. I have less issues enabling this because, well, I am working below 20mhz! I am really just trying to work as close to the actual signal so that I can learn he difference when I use the cro's features.

The only time to use *1 probes is when observing signals too small to be seen with a *10 probe.

Even *10 "high" impedance probes offer a very significant load to high speed logic signals: they aren't 10Mohm by many orders of magnitude! Plus their 6" ground lead causes ringing at ~100MHz.

Z0 or active probes are preferable.

High "speed logic" means any logic family introduced since the early 90s. I have a jellybean logic circuit with ~300ps edges, corresponding to 1GHz. 1ns/350MHz transition times are normal.

Don't forget that the speed is completely and utterly unrelated to clock frequency. The only thing that matters is the transition time. FFI: https://entertaininghacks.wordpress.com/2018/05/08/digital-signal-integrity-and-bandwidth-signals-risetime-is-important-period-is-irrelevant/

In anthropomorphic terms, the logic circuit neither knows nor cares when the next transition might occur.

In engineering terms, whether a clock single has the required monotonic transition depends on the transition time and the track length. Additionally, you can increase the setup time margin (t_su)by reducing the clock speed, but the equally important hold time margin is (t_hold) is unchanged.

In general, see the references at https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

7

Buy/Sell/Wanted / Re: wtb: Delock-95000, miniPCIe-sATA-quadport-HBA (want to buy/where to buy)

« Last post by DiTBho on Today at 08:57:24 am »

Note that coromonadalix already posted a link to the same item in their post that was apparently worth adding them to an ignore list for

I put that annoying guy on the ignore list for his attitude, not the links. when he posts links he never reads what I write and responds to me as if I were a total retard who doesn't know how to use Google, indeed in the past I had specifically asked for a stock of qty>=8 wifi cards in stock (in stock = from the same seller), and he sent me 10 different links of sellers who had 1 card each. He never reads the requests, he just wastes my time and then, even worse, he becomes touchy and annoys me with every new topic

Frankly, I'm sick of people like this, not to mention guys with ZERO public post contacting you privately saying "I have what you're looking for, send me PayPal money via Friends and Family", which is actually a scam attempt.

8

RF, Microwave, Ham Radio / Re: How to measure VSWR of tiny antennas - how to eliminate effect of VNA cables?

« Last post by Stringwinder on Today at 08:50:20 am »

Many  of the antenna designers I have met have used "Carbon-Based Foam Absorbers" to stop
power travelling along coaxial cables (and interfering with measurements). Far better than
ferrites that are narrowband in comparison. Resistive losses can also come from carbon fibres
applied correctly. Apply over the last wavelength(s) or so along the coax.

https://www.cumingmicrowave.com/products/carbon-based-foam-absorbers.html

The "320-2 C-RAM MT" data sheet has lots of information.

9

General Technical Chat / Re: Proof that software as service/cloud based, will never work for long term ...

« Last post by paulca on Today at 08:49:25 am »

As someone in that position right now, working in a company who pride themselves on their "Cloud Transformations", there are many things which people assume will cost jobs.  This usually appears to end up wrong.  However.  What does happen, which is not accounted for in those studies is "career displacement and turbulence".  This is particularly impacting on the more senior and more experienced engineers.

It's a bit like watching climate change happen out to 2100, but as everyone adapts and migrates around away from hotter parts to the now unfrozen poles the population doesn't decrease dramatically so it's okay then?  Yes?  No.  It misses the turmoil of displacement, migration and many will fall along the way.

Cloud means many, many things.  The "Cloud" I am talking about here is basically reselling AWS and Azure products.

AWS and Azure don't just "rent out" virtualised hardware, the provide massive swaths of "Codeless", "Serverless", "Application in a box", "Network in a box", "Security in a box" type components.

Developing one of these projects has nothing to do with software engineering.  Nothing.  It's just "Using a web application provided by AWS/Azure to configure a set of business components and applications also provided by AWS or Azure.

When you find something lower level to peak your interest you, it is usually found in integrating legacy systems into the new cloud arch, or migrating them. 

The trouble is.  It creates lots of jobs for the inexperienced "engineers" they pluck off the street with nothing buy an Azure certification.

Being an AWS Developer or an Azure developer and that is the headline on your CV...  you are not an engineer.  You are an application operator.  You are not much more than an office clerk using Microsoft Office.

The work is boring, dull, and worthless.  ALL of the components you will be using will be actual "real" open source components, but ALL of them will be abstracted away and renamed, protected behind APIs which force you to do things in the "AWS Way" or the "Azure way".  Of course for every Az/AWS service you consume you pay for it.  However, to intergrate outside the cloud costs twice as much.  These cloud guys are smart.  They know their market.

The trouble is that market does not know it's own business.  When they do finally atriphy away all core engineers from their upper ranks and are left with 99% business goons in the upper half and the lower half is 99% AWS Home trained button pushers...  they are 100% dependant on AWS.  AWS (et. al) know this.  It's exactly what they intend.

So if you actually want to develop software and not just "configure and integration" other peoples canned solutions, the number of sectors and businesses you can work in is diminishing rapidly.

You could go work for AWS/Azure, but, that for some reason makes me feel ill.

So right now I have some serious questions on the sustainability of my career right now.  I don't know if my skills will not become neiche in the coming years. 

Some people argue this is just natural progression.  It's just the tech landscape mutating as it develops.  You just need to keep learning the new things right?  What has changed?

Cloud.  Cloud is different.  As I said above, they are not platforms designed to help you engineer software, they are platforms designed so that you don't need to engineer software.

While "Software Engineering" is a self-deprecating endeavour - we write software such that non engineers can do things the previous required engineers to do - I think this rapid "transformation to cloud" is going to move the market for actual "Software Engineers" out of the majority of "Business solution provider" type companies and SIs.  Actually software engineering will move into more "neiche" markets and sectors and in provision of those cloud components within MS/IBM/AWS etc.

I have 11 years ideally.  More realistically 18 years before I can retire.  At the moment, I do not hold high hopes

10

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by electronics hobbyist on Today at 08:48:12 am »

Now we have two feature suggestion threads for this scope -- this one here, and https://www.eevblog.com/forum/testgear/sds800x-hd-featureimprovment-disscusions/.

Which one do we want to use going forward? This one since it has more "critical mass", or the new one for a clean start? Should the other thread be locked to avoid crossed wires?

My original plan was to discuss Improvements and Wanted Features in this thread