Recent Posts

1

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

« Last post by Mechatrommer on Today at 10:03:04 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.

Cable? My WiFi adapter cost me $7...

iircsomeone stated dho800 only works on specific brand. i have few wifi adapter here, maybe later i will try. but still its a few steps to do... rather than plugin usb stick and hit capture button.

2

Test Equipment / Re: Siglent SDS2000X Plus Hack

« Last post by gwideman on Today at 10:01:53 am »

Just posting to thank those responsible for the script and other tips. 

I will consolidate some notes that might bring other readers up-to-speed quickly without fussing around reading this entire thread:

-- SDS2104X Plus
-- Script: I used the one in message 409 of this thread.
-- Edit the script to change SCOPEID to the scope's id (from the Utility > System Info.)
---- Enter scope id in lowercase and numbers, omitting the dashes.
-- Run the script. [Note 1]  It prints a list of keys
-- Visit the Utilities > Software Options panel, select an option in the drop-down list, enter the key for that option from the script output.
---- Enter the key in lowercase and numbers.
---- You might think you'd need to plug in a keyboard, but no need, a decent one appears on the touchscreen.

Other concerns:
-- Originally the scope was at firmware V1.3.something. In that state it accepted a key for one of the options (and the option took effect).
-- The scope was then upgraded  to the now-latest released firmware, 1.5.2R3_EN
-- The scope retained the previously-set option.
-- The scope accepted additional keys for additional options.

[Note 1] The script is in Python language. You will need Python 3.something installed in order to run it -- free and easyish to install, but a burden if you have no other need for it.  Alternatively, search online for a site where you can run Python code by just pasting it into a text box etc.

Thanks again fellow EEVBlogsters.

3

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by john23 on Today at 09:57:34 am »

Hello XVR,DB02S2415A outputs 15V voltage difference between the gate and the source of the mosfet(floating).
I need a solid 20V on the drain of the TGA2590 power amplifier with respect to the source of the power amplifier.
How the DB02S2415A does that?
Can you please draw so i could understand?
For the mosfet i understood the 15V difference  floating ,but how it helps us put 20V with respect to the TGA2590 source?
Thanks.

4

Beginners / Re: Analog Multiplexer-Demultiplexer Switch Vs Input Voltage

« Last post by 2X on Today at 09:56:23 am »

For my opinion the ON Semiconductor’s datasheet is the most detailed. It clearly writes at the first table on the page 4 that Vis is the analog input voltage of the switches and the Vin voltage it corresponds to digital voltage (in respect to GND) and more precisely to control pins.

At page 10 the datasheet describes with an example the functionality of the chip. As I understand the logic level converter is referred in the function that with a positive digital signal (e.g. 0-5V) can controlled a Vp-p analog signal (e.g. +5 - -5V; with negative values). The logic level converter takes as input a digital positive signal and then creates on his output a proper signal in order to drive the gates of the mosfets/switches that are between each analog input/output.

Also, a very good detailed datasheet where is similar to 4052 is the 14052 datasheet.


P.S. If anyone understand the reason that at Nexperia's datasheet referred the term Vsw (or the Vsw is the same thing with Vis in essence?) and if there is any practical purpose of it... please tell it.


Thanks all of you for your replies and the help.

5

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by xvr on Today at 09:49:51 am »

That is exactly DB02S2415A used for. You still need it to power floating side of schematic

It"s V1 in Spice model

6

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

« Last post by shapirus on Today at 09:34:37 am »

I'd like to see a frequency sweep.

I second this.

@KungFuJosh can you please set the scope to 500 Msa/s, low waveform acquisition rate (to make the TinySA's glitches less visible), low persistence, and record a video of a 30 seconds long frequency sweep from, say, 110 MHz to 270 MHz?

Coax connection with a 50 Ohm feed-through terminator, if possible, to make the test conditions the same as in my test.

It will be interesting to see at what frequencies (and at what ratio relative to the sampling rate) it will become first wobbly and then AM-like (if it will), to compare that to Rigol.

7

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

« Last post by ebastler on Today at 09:32:24 am »

The Rigol is applying the theory correctly

When was THAT proven? 

Rigol have repeatedly cut corners in their signal processing. The sampling rate vs. bandwidth mismatch has been discussed at length here; the very generous inter-channel skew spec, wobbly AC trigger, wonky FFT "resolution bandwidth", incorrect flat-top window function come to mind as well. I would not be surprised at all if they had not gotten the Sinc interpolation quite right.

8

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

« Last post by shapirus on Today at 09:28:41 am »

BTW, speaking of signal integrity, the (unlocked) Rigol can more or less properly show signals at up to 500 MHz at 1.25 Gsa/s (the 2.5x ratio again btw), albeit with a greatly reduced amplitude, apparently because of the hardware low-pass filter on the input.

While not suitable for measurements, it will at least allow to see qualitatively if there are any unwanted oscillations up to 500 Mhz. The frequency counter fails by that time (maybe because of the reduced amplitude), but the waveform looks all right and proper frequency if you measure it using cursors.

I think it may make sense, as was suggested by several people, to mod the input filter on one of the channels (say ch4) and reserve it for the cases when a higher bandwidth input is required. Of course, that, as usual, requires to understand the limitations, knowing how to probe at those frequencies, etc.

9

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

« Last post by soldar on Today at 09:28:29 am »

This thread makes me want to bang my head against the wall. Besides all the noise and useless arguing, there is something that bothers me and it is that I believe the OP is just not qualified or certified and should not be making this type of decisions. It is one thing to ask in a forum for personal things or for professional things if one has the appropriate knowledge and background, but this, to me, screams like a bad idea.

There are too many unknown variables and the OP is, clearly, not qualified. A medical device sold professionally and for export and this is how it is being designed?  In America? Really? Nobody thinks there is something wrong in this scenario? Really?

My response would be that you need to hire a qualified engineer who does not need to ask this type of questions and who is responsible for their work.

Some months ago a friend asked me if I could repair an automatic watering system box device which had not lasted long. Proudly designed and made in the USA ... and complete crap. The power supply part was designed by someone totally unqualified for the job.  Among other things it had a resistor making lots of heat right next to components which could not take the heat and all enclosed in a weather-proof box with no ventilation. It was crap and there was really no good repair except to replace the unit with something else. ... probably designed and made in China with better design and quality.

I am all for helping people learn and develop their own projects but for commercial, professional products you need a pro.

Just the way I see it.

10

FPGA / Re: Help on translate schematics to Verilog.

« Last post by Wiljan on Today at 09:23:58 am »

(well, I use Quartus schematics for now...)?

If you use Quartus and have made a schematic, then while the schematic are selected you can click "File"/"Create/Update"/"Create HDL Design File from current file" (the schematic)  select verilog, give it a name, quartus will then make a verilog version of your schematic.