Recent Posts

1

Programming / Re: Linux Dependency Black Hole

« Last post by ataradov on Today at 01:47:23 am »

I am asking questions about the increasing problem of dependencies.

You have not actually clarified what "problem of dependencies" you have in mind. I've been using Linux since 2002, and as the only OS since 2007, and in that time I only see things improving over time (discounting whatever Canonical is doing).

So, if you can provide specific examples, there may be something to discuss. Otherwise it is just way too abstract.

2

Programming / Re: Is ChatGPT any good at writing code?

« Last post by vk6zgo on Today at 01:46:46 am »

So, no, you won't get redundant. But you're likely to get frustrated as more and more people expect these LLMs to do your job, and then come back to you to help them get out of the mess they have put themselves in. Get prepared to this to get over the frustration (the "I told you" syndrome), and you'll be fine with probably no shortage of work to do for years to come.

That's no different to what I've experienced repeatedly since the 80s: "Your $10,000 quote is too high, we found a student who said he can do it for $500".

Two years pass ...

"Hi, the student's code never worked. Can you fix it?"

ChatGPT coding might save you some typing, but it's really very much like the messages we get here and on Reddit etc all the time about student assignments "My code doesn't work, what's wrong?"  Uhhh .. everything?

It's all about perceptions.
The MBA Boss knows nothing about technology & believes all the fairytales that come out of the media, so they really believe that Chat GPT  & the like can do all these things better than a human.

3

Metrology / Re: 5.5D vintage Systron Donner 7205 DMM with 0.5% FS error

« Last post by trobbins on Today at 01:44:49 am »

I removed VR7 and confirmed no change to 0.5% FS error, so returned it.  I then checked if it was feasible to adjust the +10Vref and -10Vref levels as a way of calibrating the display value to 10V FS, and that seemed to require the internal ref levels to be lowered to circa +/-9.987 (ie. abt. -0.13% of anticipated).  The equipment instruction manual only describes calibration of the various range trims in the first analog section, effectively assuming the +/- 10Vref levels in the following analog integrator are correct.

Adjusting the internal +/-10Vref levels seems to be the simplest path forward, so I will warm everything up and calibrate the meter across the ranges to confirm everything displays as anticipated.

Ciao, Tim

4

Manufacturing & Assembly / Re: LPKF Protomat S42: Machine "shock absorber"/"stroke limiter" tuning

« Last post by rsaxvc on Today at 01:43:54 am »

> It seems that Your tool bit may be the wrong length.

That is such a a better explanation! I think I was thrown off because my machine came with a 2.95mm bit, but perhaps it is not "the" 2.95mm reference bit, which could long enough to drill into the reference strips without undoing the Z stage stroke limiter.

Say, is there any chance you would mind dimensioning an LPKF "special drill for reference drilling" bit if you've got one? I couldn't find it in LPKF's catalog.

> Adjust Your 'Z' depth accordingly in the program.
> This is the link for the software for the machine.

I believe S42 was of the last to be used with the older Boardmaster software I have, and even has manual Z stage adjustment via a large screw that adjusts the bit relative to a plastic foot, and no software Z controls other than down-time.

Thank you for your help with this.

5

Microcontrollers / Re: A couple questions about Milk-V Duo boards

« Last post by SiliconWizard on Today at 01:41:44 am »

Yep. The amount of RAM can be pretty interesting. Using a Cortex-M7, you rarely have access to anything else than PSRAM if you want more than the internal RAM, which is slow and limited to 8MB/chip (at least for the QSPI ones), or maybe SDRAM for some MCUs?

The Duo's with 256MB and over are slightly different beasts as I've seen, they include an ARM core on top of the 2 RISC-V cores. I haven't figured out yet how all 3 can work together.

6

Microcontrollers / Re: A couple questions about Milk-V Duo boards

« Last post by brucehoult on Today at 01:35:42 am »

Thanks! So, in terms of pure performance, at least from your benchmark, the C906 looks way behind a Cortex-M7 at the same clock freq

Sure. The M7 is a pretty good dual-issue uarch -- better than A7, A9, A53, maybe close to A55. And running from SRAM not DRAM helps too. The C906 is purely single-issue, in order.

Note that the Duo has massively more RAM with 64 MB (and 256 MB and 512 MB models just becoming available for only a few dollars more)

7

Beginners / Re: Help identifying these possibly RF/Microwave components?

« Last post by arlo_g on Today at 01:34:26 am »

That's a nice microscope image, Cincin. It looks like there might be edge contrast in the image: do you have Darkfield or Nomarski/DIC fitted on your microscope? 

As for the TriQuint chip, those spirals look like integrated inductors to me. That wouldn't be a big stretch on TriQuint's traditional GaAs substrates. Based on the number of inductors, and the shortage of clearly single-ended signal pads, my guess would be that this is a tuned RF circuit. Maybe an oscillator, mixer, frequency doubler or reactively matched switch/ switched reactive components?

8

Programming / Re: Linux Dependency Black Hole

« Last post by mag_therm on Today at 01:32:00 am »

I don't take it emotionally. I don't really care what you do to your system. But what bothers me is when people go on the forums and complain that "Linux sux" when they mangled their system by installing random stuff from tar.gz.

Installing into "~" is fine. Installing into "/" is just asking for trouble.

But it also depends on the type of a system. If this is some random RPi that can be re-imaged when necessary, then who cares. If this is your primary system, not destroying it is a good call.

As I wrote earlier, I am staunch linux user of 18 years, having earned my living from it and I like messing about with it now in ham radio.
from my o/p, see, I am not complaining about linux; I am asking questions about the increasing problem of dependencies.

I am retired with a few left over computers .
For risky trial stuff like trying this MCUXpresso I use a standby computer on Fedora 37 now.
On that I don't care if reloading Fedora as I like to keep it up to date

Linux is fairly fault tolerant in my experience, but when clients would ask to fix problems, I would always recommend to just reload the whole thing.
Because it is difficult or impossible to find out what somebody else did especially if they had root.

9

Beginners / Re: LM317 Based Digitally Controlled Power Supply

« Last post by TerrySt on Today at 01:26:33 am »

Hi there,

Actually I was referring to the accuracy of the set point of the voltage that would be controlling the LM317.  If the user wanted to output say 5 volts then they would have to apply about 3.75 volts to the ADJ pin.  If it was just 3.70 volts then the output would be 4.95 volts.  If the design could get that right though (3.75v) I don't think there would be any worry, but that could easily require feedback which brings in the issue of control stability into the picture.  If the designer wants to use feedback then it's going to be their responsibility to get it stable.  That means the uC will have to sample the output and make adjustments, and that means there will be a delay.

As far as regulating once the right voltage is actually applied, that may be ok but I have not looked into that in detail.

Yep.  I hope the OP realizes the issue and has a plan to deal with it.

Terry

10

RF, Microwave, Ham Radio / Re: Detecting very low power motion sensors

« Last post by ejeffrey on Today at 01:23:29 am »

TinySA Ultra can detect motion sensor frequencies around 10 GHz, in these examples

I thought it only went  to 6 but I now see there is a higher frequency version. My understanding is that it has much worse sensitivity above 6 GHz so I would count on it working.

Could ultrasonic sensors work reliably through a wall ?

Is it possible to somehow detect the emissions of ultrasonic sensors placed behind a wall ?

Depends on the wall and the sensor.  Going from wall to air, reflecting, back to the wall and to the sensor is probably a tall order?  It's also possible to hide things by e.g. drilling a hole in the wall, mounting sensors in the hole, skim coating it and painting over.

A microphone with an audio signal analyzer would work as long as the microphone works up to the frequency in use.  I think the things used in parking sensors are like 40 kHz?