Recent Posts

1

3D printing / Re: could anyone please print me a microscope Head adaptor ring

« Last post by davebb on Today at 05:25:12 pm »

Hi Roger
Thanks for going out of your way for me,i will let you know how it works,
one thing i have to ask is the stand mount that this will be fitting in has a lock screw with a point on the end to hold it in position, is there a possibility if i screw this in could it damage the ring or is the hardness ok for this, or should i try not to use this screw,
Thanks Again,
Dave 2E0DMB   

2

Repair / Re: Lecroy service manual for SDA6020 or Wavemaster 8600?

« Last post by djsb on Today at 05:24:54 pm »

A service manual for a Wavemaster 8300A would be nice as well. I have posted here about trying to fix one.

3

Test Equipment / Re: Siglent SDS800X HD 1Specifications

« Last post by martinot on Today at 05:20:39 pm »

Just put an order for a SDS804X HD scope.  Seems out of stock in Europe, but hope I will get delivery in a month or so.

Just got the scope today.

Discussion about clock time accuracy, anyone who has any open NTP-server IP to recommend for the scope?

4

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by tooki on Today at 05:19:29 pm »

getting panties in a twist over nothing…

Microsoft forcing telemetry on you is 'getting your panties in a twist'? That only seems innocuous compared to them not limiting it to the Store.

Honestly? No, I don’t think it’s a big deal. Software developers use telemetry for a lot of good, legitimate purposes, and by and large Microsoft has proven to be quite good about not using it for nefarious purposes. (I would not extend the same trust to Google or Meta, for example.) I worked in the software industry for a while, and having “seen how the sausage is made”, so to speak, installation telemetry does not give me the heebie jeebies the way a lot of other modern tracking does.

5

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

« Last post by gf on Today at 05:18:17 pm »

1) oscilloscope is not properly BW limited, so Sinc filter is unable to reconstruct perfectly, instead of nice sine, it creates AM sine.

140MHz is below Nyquist.

Referring to the photo in post #436, one cycle of the undulation frequency occurs every 5 cycles of the  varying amplitude 136.17 MHz which makes the undulation 27.234MHz.  So one sideband is 136.17 + 23.234 which is 163.40 MHz. That is more than half the 312.5 MHz sample rate.

If the signal frequency is 136.17 MHz (according to the frequency counter -- don't know if it can be trusted here), then its image in the 2nd Nyquist zone is 176.33 MHz. Ideally, the image should be eliminated by the interpolation filter. But if the interpolation filter does not provide sufficient attenuation at 176.33 MHz, then we see the interference between the two frequencies as "AM". The result is as expected when a Nyquist filter is used as the interpolation filter.

The problem here is that the conditions of the Nyquist-Shannon sampling theorem are not fulfilled and therefore it cannot be used. We do not have the required infinite number of sampling points. The infinite number of sampling points is essential in the proof of the Nyquist-Shannon sampling theorem.

Does anyone know a sampling theorem that only requires a finite number of sampling points?

A realizable reconstruction filter (with finite length) just lowers the highest frequency which can be reconstructed (almost) exactly.
Instead of sampe_rate / 2, the limit decreases to say samle_rate / 2.5 or samle_rate / 3,... (depending on the filter).
Frequencies beyond this reconstructability imit are either attenuated, or reconstructed with the observed "AM effect" (again, depending on the filter).

6

Test Equipment / Re: At last, Siglent's SDS5054X touchscreen DSO...

« Last post by 0xdeadbeef on Today at 05:16:31 pm »

SDS5000X Firmware_V0.9.9R3 (Release Date 04.26.24)
https://www.siglenteu.com/service-and-support/firmware-software/digital-oscilloscopes/

CAUTION: This release cannot be downgraded to previous releases.

• Compatible with new hardware
• Supported new probes: SCP5030A/SCP5150/SCP5500, SAP5000D
• Trigger: modified the trigger strategy of /AND and OR trigger from FALSE-to-TRUE to TRUE-to-FALSE
• Acquisition: modified the Average strategy in Single mode from acquiring one frame to acquiring averaged X frames (where X = Average count)
• Optimized UI
• Fixed several bugs
  
  • a) Freezing issue in Roll mode
  • b) Freezing issue relative to Stop-on-Search-Event in Search mode
  • c) In some case the scope does not update the waveform traces after a long time

7

Beginners / Re: Checking for noise in resistors

« Last post by Xena E on Today at 05:14:08 pm »

Hello Calambres...
It can be done but why bother? If the resistors are old carbon composition types they will have likely drifted high in value and be very noisy, (the two problems go hand in hand).

Carbon film types are usually more stable and lower noise.

Just swap them out for metal oxide types, they're cheap enough.

Regards Xena.

8

Projects, Designs, and Technical Stuff / Re: Building a DIY Curve Tracer

« Last post by 77Ribetts on Today at 05:12:56 pm »

Hi i am keen to buy a set of boards especially more since the BOM price of 600 euros
is for 10 curve tracers not 1.. although i am still not sure if anyone could clarify this i would be grateful

9

Test Equipment / Re: New 2ch pocket DSO+SG - Zeeweii DSO2512G

« Last post by Aldo22 on Today at 05:12:11 pm »

What is the newest firmware?

I don't know, probably 1.3.0c.
Try this (instructions by ptluis)

**Open user calibration function.
How to perform AC Gain calibration:
1. The oscilloscope measures the 2.5V 1Khz sin waveform. Observe the "PKPK" measurement item.
2. Open Menu-> Meas, then press the CH1CH2 button, and then long press the [mV] key to enter the AC Gain calibration mode.
3. The UP DOWN button is used to increase/decrease the CH1 Gain until the "PKPK" voltage is equal to or close to the voltage of the signal generator.
4. The LEFT RIGHT button is used to increase/decrease the CH2 Gain until the "PKPK" voltage is equal to or close to the voltage of the signal generator.
5. Press the OK button to exit and complete the calibration.

How to perform DC offset calibration:
1. The oscilloscope measures the DC power supply. Observe the "Mean" measurement item.
2. Open Menu-> Meas, then press the CH1CH2 button, and then long press the [V] key to enter the DC offset calibration mode.
3. The UP / DOWN button is used to increase/decrease the CH1 dc offset until the "Mean" voltage is equal to or close to the voltage of the multimeter.
4. The LEFT / RIGHT button is used to increase/decrease the CH2 dc offset until the "Mean" voltage is equal to or close to the voltage of the multimeter.
5. Press the OK button to exit and complete the calibration.
Different vertical sensitivities use different calibration parameters, so they need to be calibrated separately.


**add [ZOOM]
Long press the "s" key to turn on/off Zoom mode.
(Zoom is not supported when roll mode or cursor is on\
It is recommended to exit Zoom mode before shutting down to avoid measure item are cleared)

https://www.eevblog.com/forum/testgear/new-2ch-pocket-dsosg-sigpeak-dso2512g/msg5083081/#msg5083081

10

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

« Last post by egonotto on Today at 05:06:07 pm »

Hello,

The problem here is that the conditions of the Nyquist-Shannon sampling theorem are not fulfilled and therefore it cannot be used. We do not have the required infinite number of sampling points. The infinite number of sampling points is essential in the proof of the Nyquist-Shannon sampling theorem.

Does anyone know a sampling theorem that only requires a finite number of sampling points?

Best regards
egonotto