Recent Posts

1

RF, Microwave, Ham Radio / Re: Drive a piezo at 6.78mhz

« Last post by ryba7 on Today at 11:36:24 pm »

Thanks for all infos. I will perhaps not need all the 400w, i will see if i can obtain my results at lower power, but it would still be nice if it could work.

it looks that you're forgot to calibrate VNA with the cable to see impedance on the end of cable exclude the cable influence.

But the oscillator see all the cable + piezo/coil impedance, no ? So Then if i only measure the coil/piezo i will have a result that do not correspond to what the power source actually see, with the 1 meter cable in place, producing missmatch ?

2

Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread

« Last post by mnementh on Today at 11:34:41 pm »

THEN I go to assign footprints to every component on the schematic before I can run PCBNew and ... and..... picture below. Oh no.... Kicad can't fucking find the footprint library, I am screwed, so much for upgrading to the latest and greatest !!!   

What now ? Spending days on Ubuntu and Kicad forums hoping it's a known problem and someone can take my hand to fix it promptly?! 

I'm a complete *NIX fuckwit, but something looks hinky in that directory path. Like something is missing between slashes or a extra in there.

mnem
 

3

Microcontrollers / Re: Same CRC routine returns different results... :o

« Last post by DavidAlfa on Today at 11:33:11 pm »

You're overloading yourself! You need to close everything and go for a walk!
My advice is to go to a nearby quarry and ask for 1-day job breaking stone with hand tools.
After that, take a shower and a long nap. 2-3 days later you will wake up like new!   

4

Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread

« Last post by BU508A on Today at 11:31:17 pm »

With the background that most people here probably have, you can tell pretty quickly who's serious and who's a windbag. Of course, the first thing is to find the point of how you present something. But with Shahriar, you could see from the beginning that his standards are academic and that's something I really appreciate.

I'm not saying that Mr. Carlson explains things wrongly, but the way he does it I think is a failed attempt to be sophisticated and at the same time suitable for beginners.

I am similarly critical of ElectroBOOM (Mehdi). It is obvious that he knows what he is doing and his explanations are accurate. What bothers me about him is the comedy element in his presentations. I appreciate his kind of self-irony, that he doesn't take himself too seriously. At the same time (for comedy reasons imho) he lacks respect for mains voltages and high voltage and high energy systems with his feigned carelessness. I only remember his stunt with the Jacob's ladder.

Translated with www.DeepL.com/Translator (free version)

5

Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread

« Last post by Vince on Today at 11:24:58 pm »

Dave did a one on one interview with Shahriar a few years back you might like to dig out.

Yes I watched it of course, might have done 2 videos with him actually IIRC.

I also listened to the interview he did with him on his "radio" podcast, The Amp Hour.

6

RF, Microwave, Ham Radio / Re: Testing the effects of releaving ground plane beneth a component

« Last post by joeqsmith on Today at 11:24:31 pm »

I looked at the free version of Sonnet.  It was too limited to get anything working.  So I tried an old version of Ansoft.  I was able to get a simple EM simulation to run and even tried creating a model based on the Touchstone file.   Both ran fine however, once again it appears too limited to allow simulating what the OP had asked about.  I am not aware of any other free tools.     

http://www.gunthard-kraus.de/Ansoft%20Designer%20SV/English%20Tutorial%20Version/index_english.html

7

FPGA / Re: FPGA VGA Controller for 8-bit computer

« Last post by BrianHG on Today at 11:23:20 pm »

What's the pull up resistor on the bus?

8

Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread

« Last post by Vince on Today at 11:23:05 pm »

 
Just redid the schematics from scratch for my little Kicad project, now that I ahve upgraded to the latest Ubuntu version, 21.04, hence Kicad 5.1.9.

Doing the schematics was painless, then I run ERC, does not complain too much, other than the ground symbol somehow annoying it, don't know why.


THEN I go to assign footprints to every component on the schematic before I can run PCBNew and ... and..... picture below. Oh no.... Kicad can't fucking find the footprint library, I am screwed, so much for upgrading to the latest and greatest !!!   

What now ? Spending days on Ubuntu and Kicad forums hoping it's a known problem and someone can take my hand to fix it promptly?! 

9

General Technical Chat / Re: Rechargable vs. Non-Rechargable Batteries - AA/AAA Size

« Last post by Miti on Today at 11:21:57 pm »

And these are the new models. Still made in Japan.

10

Microcontrollers / Re: Why do people not like Microchip?

« Last post by DavidAlfa on Today at 11:21:14 pm »

When you went with low end models, you had a lot of drawbacks. But you get used to them.
If you wanted power, the dspic33s were beasts. 40 MIPS, mostly single-cycle instructions, 48KB ram in a 28PDIP... crazy and expensive!

The harward architecture has its benefits. ARM core can only access the work registers, so first it needs to load the address, fetch the data and then work with it, while pics usually can address anything, ignoring the bank selection thing.

For example, toggling a GPIO:
- PIC, clear/set/toggle RA3: bcf/bsf/btg LATA,3
- ARM: Load address of GPIOA->ODR into the register (pointer)
           Get the value
           Modify the bit(I barely know any thumb/arm asm, but I guess it uses a OR/AND/XOR mask, so at least another 2 instructions)
           Write back the new modified data using the already set pointer
           But also arm is pipelined, so the real behavior is different.

The xc8 compiler works pretty well. Last time I checked the disassembly, the optized code was really good.
But I also remember manually adding assembly instructions in a pic24 because mplabc c16 (Now xc16) didn't use the hw div instructions.
About the peripherals... Some were really buggy.  But also stm32 has some serious issues.  Even the newest ones.
So it seems there's crap everywhere. I'm starting to think there's no mcu on earth that works like in the papers.
Lots will require reset and initialization when something goes wrong.

"Use the enable/disable bit to reset the spi peripheral"- Best joke of the last 20 years!  

I don't hate pics, but they got really old once the arm came into the game.
Never understood why there isn't GCC for them. AVR is pretty similar and has been supported since long time ago.