Recent Posts

1

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

« Last post by gf on Today at 01:48:21 pm »

Here you go:
SDS824X HD_Sine_450MHz_1GSa_Single

here you demo that at some setup Sr / 2.22, sds800x is unable to reconstruct signal properly? from the look of it, yes it is.

The image seems to be named incorrectly. This was 490 MHz, or sample_rate / 2.04.

2

Test Equipment / Re: Standardised Way To Test Oscilloscope Screen Update Rate

« Last post by bdunham7 on Today at 01:42:45 pm »

Your video requires some codec I don't have.

That's Windows pissing in your ear and telling you that it is raining.  HEVC (h265) has been around for quite a while now, but MS still wants a fee to let you use it.  Download VideoLan if you want a decent video viewer.

https://www.videolan.org/vlc/download-windows.html

It seems to stutter or stall at times and then plays catch up.  I had turned off all the readouts and such and set the scope software to the highest screen priority but with Windows not being a RTOS, I am not too surprised.

Those stutters and stalls are the main thing that makes a display annoying and not 'live'.  I think a consistent 30fps might be marginally sufficient for most people in most cases just like video, but throw in 5 consecutive missing frames every two seconds and everyone will hate it.

3

Test Equipment / Re: Magnova oscilloscope

« Last post by Martin72 on Today at 01:41:53 pm »

Or "The Signal Path" for in-depth analysis, including software implementation.

I didn't know him at all...
But yes, it should go in that direction, because the task would first be to find out what this scope has/can do better than other competitors in the price range.
That's the big question.
And that only works with a deeper analysis.
It may look like a tablet, but it's not a portable scope (and so micsig is still quite alone).
It has a relatively “low” bandwidth and “normal” memory size.
So where are the advantages, that would have to be found out and presented.
The “Dave Show” would be less suitable for this.
However, if performa01 had the time and inclination to do a review like the recent SDS800X HD, it would be a win-win situation for everyone, including Batronix.

4

FPGA / Re: Analog video output with FPGA ?

« Last post by radiolistener on Today at 01:40:52 pm »

The problem with R-2R DAC is that it has many parallel wires which length depends on PCB layout and soldering. As result, you will have phase error for different bits. At higher frequency it leads to worse error and it limits the real resolution of the DAC.

If some color distortions is not an issue for your needs, then you can try discrete R-2R DAC. This color distortion will depends on picture which is displayed. But its more easy to use DAC chip, because it can guarantee real DAC resolution.

I think 24-bit color resolution (8+8+8 for r+g+b) is just impossible with discrete R-2R DAC at 5-7 MHz bandwidth due to physical limitations.
 

5

Power/Renewable Energy/EV's / Re: Synchronous Buck with Schottky anti-parallel to Synch FET?

« Last post by __steven on Today at 01:37:10 pm »

I remember reading that it is less so about the forward voltage drop and more about the reverse recovery characteristics of the diodes in question. Almost all IC's have deadtime between when the switches are turned on. During the deadtime, both switches are off, and the low side FET's body diode conducts. This can cause voltage spikes on the output during the body diodes reverse recovery. Sometimes a diode with better reverse recovery characteristics compared to the body diode is used to avoid this.

The datasheet specifies 22ns which seems pretty reasonable, and schottky diodes are pretty much a requirement for this. I could not find the original paper that I got this information from, but a quick google search brought me this:

How a Small Schottky Diode Minimizes Noise in Synchronous Converters:
https://ez.analog.com/ez-blogs/b/engineerzone-spotlight/posts/how-a-small-schottky-diode-minimizes-noise-in-synchronous-converters

You may be right however, if during inductor commutation the external diode has a greater voltage drop than the internal diode, the external diode may not conduct at all. I imagine that these diodes are primarily for lighter load conditions, less than 10Amps by looking at the datasheets.

Let me know what you think.

Steven

6

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

« Last post by shapirus on Today at 01:33:04 pm »

I'd like to see an actual AM signal fed into the Siglent to see what happens.

This is a very good point. It would be interesting to see how the Siglent copes with an AM signal with the carrier frequency same as those used for the screenshots above and the modulation frequency say somewhere around 1/20..1/5 the carrier frequency. It would allow to see if the Siglent applies any special "cheating" for better interpolation. I personally doubt that, but doubts can only serve as a motivation to conduct an experiment.

7

Beginners / Re: Any off-the-shelf clock using DS3231?

« Last post by hap2001 on Today at 01:31:55 pm »

I think it would be possible to hack a better reference into any cheap quartz clock? You can buy SMD 32kHz TXCO modules cheap. I think those salvaged 10MHz oven oscillators are probably the next step up in cheap precision.

Around here you better spec exactly how much drift you can stand or someone will suggest using an atomic clock.

Yes I thought that earlier, and here's my found: https://electronics.stackexchange.com/a/629657
https://dpwe.github.io/arduinoclocks/2022-07-21-bedside-tcxo.html
In this case it maybe better to just use a TCXO instead of a full RTC like DS3231.

I don't have a hard limit since it's for personal use anyway, but I think 1 minute drift per year would be good enough.

8

Projects, Designs, and Technical Stuff / Re: Is this circuit adequate to interface a uC with a dc motor using an optocoupler?

« Last post by FBMinis on Today at 01:31:10 pm »

The "fet with switch" I included in the schematic next to the motor represent the microcontroller on the water dispenser, which turns ON/OFF the pump when its button is pressed.

9

Test Equipment / Re: Rigol DHO800/900 Oscilloscope Bug Reports + Firmware

« Last post by Mechatrommer on Today at 01:30:53 pm »

After a restart, it would apparently want to load that last used state (maybe waited for a trigger to happen to fill in that buffer?), and that took ages. But eventually it booted.

that means, last setting is stored somewhere not in sd card. but where? we need to find a way to zero those memory..

In the SRAM chip. I assme they don't want to wear the flash out by writing to it after every single twist of a knob.

what are you smoking again my friend? SRAM is volatile... https://en.wikipedia.org/wiki/Static_random-access_memory they can do it in Flash and save setting at every "Power Off" button, not every knob twist. not everybody can do 100K times power on and off, which is the write endurance of Flash.

10

Other Equipment & Products / Re: Dymo 550 Thermal Printer DRM Hacking

« Last post by RethoricalCheese on Today at 01:26:32 pm »

Sadly even 17 is not enough to roll over.

Btw, size should be 2 bytes because some rolls exceed 255 stickers.