Recent Posts

1

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by ebastler on Today at 09:02:42 am »

that lead to proper Sinc reconstruction reveals siglent DHO800X can do it properly unlike Rigol, this can also can help user make decision whether this is important or not.

When was THAT proven?

In reply #465, 2N3055 showed stable reconstruction of a 220 MHz sine which was sampled at 500 MSa/s. So the SDS800X HD can still resonstruct properly at a sampling rate of less than 2.5x of the signal frequency, while the Rigol started to show wobbles at 3x or so.

Let's call it a demonstration, no a "proof", since this was just a quick one-off test.

2

Beginners / Re: Why are thermal jumpers so expensive?

« Last post by Kleinstein on Today at 09:02:19 am »

The cheap resistors are likely an easier to handle ceramic than the high thermal conductivty AlN. So they look like resistors, but a different material.
A bit point is the small quatety for a niece product with little competition. They probably get a lot cheaper once you look for millions of them.

AFAIK AlN ceramic is used for ceramic knifes, though the requitements on the material could be a little different.

3

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by PlainName on Today at 09:01:34 am »

Some developers use telemetry to figure out how people use their software

Shouldn't that be done in-house, or at minimum with users that agree to be monitored? Are you happy with your car telling the manufacturer where you went, what speeds you did where, how you used the brakes, your acceleration, where you were looking, how you flash the lights, etc? What time you go to work, the shops, hey - is that the place where Ms Periwinkle's car is parked and it's always 8pm to 10pm?

4

Projects, Designs, and Technical Stuff / Re: more modern version of tl494?

« Last post by strawberry on Today at 08:59:35 am »

buck with synchronous rectification for output voltage below ~20V
can use current mode controller , TL494/7500/3525 is voltage mode controller
small transistor silicon chip mean larger thermal resistance or silicon temperature = lower reliability

5

Projects, Designs, and Technical Stuff / Re: Brymen BC-86P USB-Adapter - Firmware with USBTMC & SCPI

« Last post by HubertGlaubke on Today at 08:55:01 am »

It sounds like you've been quite industrious in tackling the compatibility issue with your Brymen multimeter and the USB adapter. Converting the firmware from assembler to mikroC, and then to an MPLAB X project with XC8, shows a significant effort in modernizing and maintaining your project.

Using the USBTMC protocol and SCPI commands allows for versatile communication between devices, and it's great that you've been able to implement this functionality in your firmware. Being able to modify VID/PID and string descriptors via SCPI commands adds flexibility and customization options to your setup.

6

Repair / Re: Tek FG502 fails at high frequency end of dial - help needed!

« Last post by gcwills on Today at 08:53:48 am »

Success
After a lot of extra time spent on this challenging function generator I stumbled upon a fix for the oscillator dropout. I focused my attention on the area around Q292 and Q290 as it appeared that there were bias issues associated there.
Partly out of desperation I added some resistors from the collector of Q290 to ground and the oscillator was able to maintain oscillation a little further up the dial. I then tried the same approach to the collector of Q292 to no effect so I wondered if increasing the value of R155 (the Q292 load) would have a positive result. As it turned out it did and adding a 100 ohm resistor in series with R155 (820 ohm) allowed the generator to operate fully to the high end of the frequency dial. I then removed R155 and the 100 ohm and substituted a 1K 1/2W resistor. I was able to confirm that the generator worked fine across all of the ranges and waveform settings. The generator was then calibrated according to the manual.

So was this a bodge or a repair? I think it is a repair as the generator didn't have any faulty component that I could find and worked albeit in a limited way. It just failed to oscillate on certain settings. My guess is that there was sufficient drift in components around the oscillator causing this issue. Increasing the R155 value a small amount increased the loop gain enough to resolve the issue. Of course I am open to better brains than mine with better explanations?

7

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Fungus on Today at 08:52:55 am »

that lead to proper Sinc reconstruction reveals siglent DHO800X can do it properly unlike Rigol, this can also can help user make decision whether this is important or not.

When was THAT proven?

Siglent has a higher sample rate.

Rigols aren't forced to work at 312.5MS/sec.

8

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by bd139 on Today at 08:52:11 am »

There is no good purpose for telemetry, it is needed only for malicious purposes

What a myopic, hysterical, uninformed, and untrue claim.

There are definitely some uses for telemetry that are absolutely beneficial to the user: crash reports and usability research. Developers use crash reports to figure out what the most common application crashes are, so they can fix them.

Stable software benefits the user.

Some developers use telemetry to figure out how people use their software: which features actually get used the most? How do people access them (toolbars? Menus? Keyboard shortcuts? Right-click menus?) Which commands get used in what combinations? For example, knowing which commands are often followed by “undo” tells you it’s an error-prone feature. Microsoft’s use of usability telemetry has directly resulted in lots of usability improvements, for example the handy little menu that appears after pasting to let you format the pasted data. Knowing which features are used and how can help guide what features get prioritized for development.

Usability benefits the user.

Your reasoning is detached from the outcome.

Yes crash reports and usability reports are good data sources.

Do they benefit the user? That depends on the sausage factory in the middle of the process.

I have never seen an outcome that is user beneficial from a usability study. I posit that they are run by people who have no idea what they are doing.

As for the other point, my day job for the last couple of years has been running the reliability engineering team for a very large fintech. If you think that a crash dump results in a viable outcome for end users even 5% of the time then you are naive. Most of the time it is just noise. We get thousands of them an hour. And that is considered normal. Even if we do perform a causal analysis on a statistically common one, finding an engineer who can actually understand or solve the problem in a complex distributed system is an uphill battle as well.


The general theme in the thread above is there aren't a lot of people who know what they are doing. They are all making appropriate looking dances though and people who don't know what they are doing look at those and think they might know what they are doing. It's not turtles, but incompetence from the top to the bottom.

And that's why we shouldn't trust, not because the idea is bad, but the competence is bad.

9

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Mechatrommer on Today at 08:49:19 am »

Screen capture over network still works even on an unsigned app.

not everybody like to connect to network for a mere screen capture, i do it with usb stick. my ethernet cable is super long and its quite a mess trying to run it to my dso, at my lab setup, connecting to usb cable is much easier. and that luckily i have ethernet cable at all so i can do some adb hack albeit a bit inconvenience. ymmv.

10

RF, Microwave, Ham Radio / Re: High bandwidth FM signal generation

« Last post by pdenisowski on Today at 08:49:01 am »

1. Using Software Defined Radios (SDR) - SDRs do not provide large bandwidths as per my requirement
2. Using Analog Front End ICs, such as AFE7900 from Texas. This looks expensive solution and tedious

Any other solutions to think of?

A vector signal generator can provide wide bandwidths, provide complete flexibility in terms of signal characteristics (modulation, noise, etc.), and typically have a relatively simple user interface (but can also be controlled programmatically and/or can use signals created in tools like MATLAB).

That said, they may be slightly outside of your budget

https://www.rohde-schwarz.com/us/products/test-and-measurement/vector-signal-generators/rs-smw200a-vector-signal-generator_63493-38656.html