Recent Posts

91

Projects, Designs, and Technical Stuff / Re: digital RGB LED question

« Last post by glenenglish on Yesterday at 08:56:47 pm »

well, they were not really triangles, they have rounded tops.

Square waves have a rich odd harmonic spectrum, so they are more likely to produce EMI issues at higher frequencies
In addition, the high frequency harmonic content can excite parasitic reactances in the wiring (stray C, L)  which generates rings and spectral components up into VHF and UHF. (maybe 1000 times to square wave fundamental frequency)..

Start with a sine wave wave, and progressively add odd harmonics and you'll end up with a square wave.

92

Beginners / Re: Convert US standard 115V to International 230V

« Last post by Zero999 on Yesterday at 08:54:03 pm »

In order to support both 50 Hz and 60 Hz standards, the device needs to be rated to work at least within frequency range from 48.5 Hz to 61.8 Hz. This is because it needs to support allowed mains frequency variation ±3%.
…

Once again, did you read the thread? It was figured out already that the device is using switching power supplies which support both AC voltage and frequency variants on the input.

Radiolistener, can you delete your posts?

Unfortunately, that would mean him admitting he's mistaken and going by his posting history, is something he appears to be unable to do.

I find it quite remarkable how someone whose username is “radiolistener” can be so very bad at listening!

My favourite one was when it took several pages to explain why a capacitor connected to a generator doesn't increase the power consumption, ignoring the tiny extra I²R losses.

93

Projects, Designs, and Technical Stuff / Re: PC74hct4046ap Replacement

« Last post by Benta on Yesterday at 08:53:18 pm »

active loop controller- the heck is that 

Well, R303, R304 and C302 comprise the "loop filter" or "loop controller" setting the dynamic behaviour of your PLL as well as suppressing ripple from your "custom IC".

Very primitive, but in many cases enough for a "charge-pump-PFD", which your "custom IC" might be.

It may be improved a bit, but a major leap would be replacing it with an active filter.

PLLs are math heavy in design.

94

Programming / Re: Linux Dependency Black Hole

« Last post by mag_therm on Yesterday at 08:49:40 pm »

battleship to go after a trawler

It is 28 of .c and .h files. I wanted to put breakpoints to trace through the math which is meandering  over at least 3 of the .c
And the headers are all mixed up hard for me to follow I think due to multiple versions over 10 years.
Can all that be done in eclipse and gdb?

And Thanks for your time on this.

95

Test Equipment / Re: frequency displayed in Hz

« Last post by Pin240 on Yesterday at 08:48:26 pm »

This is not possible with normal settings, afaik.
Maybe DavidAlfa can tell you something about the firmware question. I don't know whether this is possible with reasonable effort.

His experiments killed the apparatus. Now I'm fiddling with dsoflash((
Who has a backup using dsoflash For DSO 2C10?

96

Microcontrollers / Re: SD Card reliability in SPI mode

« Last post by DavidAlfa on Yesterday at 08:44:34 pm »

Are you writing to the same area or adding more data to an existing file?
Most of SD cards don't have wear leveling, so if you're always erasing/writing to the same sectors the SD will wear out pretty fast.
There're some embedded-friendly filesystems supporting wear leveling, like littlefs.

I don't think there's any reliability difference in SPI mode, however in that mode CRC is disabled by default, so it might lead to corruption.
So it's always a good idea to enable it when possible with CMD59.

97

Repair / Re: Rigol DP712 Output Shorted; Fuse? / I Screwed Up

« Last post by zanfar on Yesterday at 08:43:28 pm »

I have this photo, let me know if you want additional ones. Visually, the rest of the board appears fine.

98

Manufacturing & Assembly / Re: Source for small "potting boxes"??.....

« Last post by tooki on Yesterday at 08:42:57 pm »

Why not order from a reputable vendor like DigiKey? “Box, potting” is a type of box you can filter for in the Boxes product subcategory.

 https://www.digikey.com/short/8ttbh7jt

99

Other Equipment & Products / Re: Filter advice please on home made fume extractor

« Last post by HobGoblyn on Yesterday at 08:40:31 pm »

Do you think this will be OK?

£16.50 for 2.5 kg

https://www.ebay.co.uk/itm/351226809710

Thanks

 

100

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by SiliconWizard on Yesterday at 08:37:24 pm »

I initially thought of it as a Facebook for work related stuff. So you could make use of the contacts you have at work and not have them see the crazy stuff you get up to at the weekend.

I avoid it mostly as it wants to be a job advertising website and is infested with agencies trying to sell me a job that I left years ago.

Some of the headhunters are completely useless. I had one that cold called me on my work phone to try to poach me. I was sitting 1.5m from my boss.

I've had a headhunter call me at my workplace too, company phone! - which I thought was pretty dumb.

I can beat that.  I've had one email me on my work email about a new job offer. Come on, man... How stupid can you be...

I think that some (many?) HR dumbasses just use the first phone number/email they get ahold of for a given person and use that without a second thought. It's the same method as spamming. They play the numbers and statistically get some results.