Recent Posts

1

Beginners / Re: LM317 Based Digitally Controlled Power Supply

« Last post by Kleinstein on Today at 07:50:02 am »

The circuit with the LM317 as a power transistor replacement would need a negative supply for the OP-amp. Otherwise it would not work below some 1.2 V and could not limit the current with these low voltages (e.g. with a short).

2

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

« Last post by Fungus on Today at 07:47:23 am »

There are specific posts in this thread covering most of this, but a summary doesn't hurt.

Rigol Pros: HDMI, VESA mount, WiFi built in.

Smaller size, battery option, more accessible UI, easy/neat Wifi with web/ftp access to the 'scope...

Rigol can go to 100MHz (or 125MHz) but is severely limited by its sampling rate.

Nope. Rigol can go to 280Mhz measured bandwidth, and shows signal far beyond that.

I wouldn't leave it at that bandwidth for general use but it's there if you need it and it only takes about 10 seconds to switch the model.

There's also 225MHz, 200Mhz and 125MHz options.

The lower sample rate sounds scary but when you're looking at real-life signals with probes clipped onto wires? Not so much.

(And there's no problem at all with 1 or 2 channels)

3

Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by Kleinstein on Today at 07:46:23 am »

There is no need for a super stable clock. The point is jitter over a time frame of some 10 µs. The switches and an optional buffer to improve the isolation would add a few ps of jitter anyway. So a standard crystal oscillator should be good enough.  The crystal directly at the RP2040 as for the RP-pico could have an issue with the internal state effecting the clock - I had this issue with the AVR and this caused quite some INL error (e.g. 10 ppm range). Chances are 12 MHz directly with no PLL could be fast enough for the ADC, though this would not allow to use the USB while using the ADC.

4

Repair / Re: Mig welder wire feeder controller board not working

« Last post by TERRA Operative on Today at 07:45:12 am »

A little off topic but wire feed related. Since repairing a no wire feed problem with my brother's WIA 250i, it now will stop feeding if an arc doesn't strike within a second of pulling the trigger. Seems to be a feature that has been activated somehow, but no mention of it in the manual. Not a problem in practice.

Apparently, the wire should feed normally for 5 seconds, then run at full speed (for feeding wire down the MIG Gun etc).
Might be an issue with the current sensing somewhere, but I unfortunately don't have access to the WIA service portal anymore to get the full schematics (if available).

5

Test Equipment / Re: New Hantek DSO2X1X models?

« Last post by Pin240 on Today at 07:41:41 am »

Working or not, after 3 boots (Wait until the second Hantek logo shows up, then another 5-10 seconds) the original file will be restored.

Thanks for the script

6

Projects, Designs, and Technical Stuff / Re: No interrupt from AS6501...

« Last post by dietert1 on Today at 07:41:08 am »

The app note source codes are in C and C is portable. As a proof of concept you could port the app note to your MCU. Probably you have support for the peripherals needed (GPIO, Interrupt, SPI..)
Coding in assembler can be a second step once it works.

Regards, Dieter

7

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

« Last post by tautech on Today at 07:36:43 am »

As you know display HW is different so some HW analysis should reveal the reason for apparently faster display rates in SDS2000X HD.

File convertor in the webserver virtual button is a little app to convert BIN files to CSV.
It can also be downloaded to USB from the Save/Recall menu to be then transferred and installed on PC.

Setting the LAN address requires clicking OK and reopening the LAN menu to see the IP DHCP has assigned.

With mouse plugged into the scrope the scroll wheel is available for making numeric field adjustments.

8

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by eTobey on Today at 07:33:21 am »

Any advanced user with some active Math channels.

A few more words would have been useful, and would have sounded much nicer...

From the guy who always tells me he prefers short answers to long winded ones. 😉😉

The guy, that knows about the difference between sentences, paragraphs and chapters...

What about staying on the technical side, huh?

9

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

« Last post by nctnico on Today at 07:33:21 am »

I am thinking about the purpose of the refresh rate.
Perhaps the screen refresh rate is less important than the ability to display the waveform appropriately – so a waveform with a 'glitch' repeated at different rates could be used to test for this.

Yes, in theory the display refresh/update rate shouldn't matter if the scope is designed to or set up to capture the thing you are interested in. Persistance is one obvious way to do that for example.
But often you are just causally using you Mk1 eyeball probing around, in whcih case you don't want your fast waveform capture rate hindered by a slow display update rate.

This really is a non-issue which has been discussed before. Any form of high-waveform update rate will have a certain amount of persistence time to make sure the signal stays on the screen long enough to be noticed. Think in order of magnitude of 200ms. Anything below is likely to be missed. If you think about it and think back about the relative long fade times of phosphorus used in CROs, you'll come to the conclusion that the display update period can't be a parameter in the process which shows the signal.

10

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by eTobey on Today at 07:30:26 am »

How about making the tabs a tiny bit smaller too?

Not possible without sacrificing space needed for indication of channel settings.
BW limit, Hidden (but active) etc.

Based on your information, and what i found in the manual the statement "Not possible" is wrong. See picture.