Recent Posts

1

General Technical Chat / Re: Post a picture of a cat!

« Last post by BU508A on Today at 08:32:07 am »

cat video from NASA:



Background:
https://www.nasa.gov/missions/psyche-mission/nasas-optical-comms-demo-transmits-data-over-140-million-miles/

2

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

« Last post by dazz1 on Today at 08:28:40 am »

Well it will work for what you were doing but there are some issues.

The loading on the GPIB bus will be much higher. About 10k plus a fair bit of capacitance instead of 100k and <10pF
The logic thresholds will be incorrect.
It's technically exceeding the input voltage specification of the 'scope. The specification is +_40V at the probe tip. As the probe network is a 10:1 divider that is +_ 4V at the 'scope digital input. Now 5V is unlikely to cause damage but any overshoot, ringing or higher logic levels than TTL could damage the comparators in the 'scope.

Adding a pair of 100k 8 way resistor packages is not too much extra work.

Robert.

All good points. I didn't spot it was a 10:1 divider.   I am going to revisit the design.  I suspect it will be easier and less work to insert discrete smd resistors to the existing track layout. 

3

Test Equipment / Re: SDS800X HD Bug Reports + Firmware

« Last post by ebastler on Today at 08:26:10 am »

As suggested yesterday, I checked which of the "modern" triggers (Qualified, Delay, Nth Edge, Setup/Hold) are affected by the recently found trigger-related bugs, to get a complete picture. Results are mixed:

#17 Wrong trigger threshold displayed in zoom mode
Qualified, Delay, Setup/Hold are affected
Nth Edge is OK

#16 Trigger settings are lost upon reboot
Qualified, Delay, Setup/Hold, Nth Edge all forget their complete setup:
Assigned channels, thresholds, delay/timeout settings, edge count setting are lost.

#15 Normal trigger does no resume after wrong threshold is corrected
Delay trigger is the only one affected.
(Clarification: Only change of a Source A threshold in the dialog causes this.
Change of Source B threshold via trigger level knob is OK.)

Qualified, Nth Edge, Setup/Hold are OK.

#14 Edge trigger setting affects Qualified trigger operation
I could not reproduce this one at all.
More information about the settings is needed. @eTobey?

4

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

« Last post by Sham73 on Today at 08:19:59 am »

I wanted to find out whether it is possible to determine details using such a digital 2-channel device or not.

I'm not an expert, but I don't see why there should be a difference between digital and analog in this case. They just measure voltages.
The problem is probably more with the "stimulus" and the probes.
Perhaps an SMD tester like the Mastech MS8911 would be suitable?

I also think that there should be no difference between analog and two-channel digital in this regard. As for the Mastech MS8911, it is an ordinary multimeter made in a pliers form factor, and therefore it will not be able to determine parts in-circuit.
In a word, I purchased Zeeweii DSO2512G (V9.15). I liked it - a fairly high-quality device. But I had a couple of questions: 1) What does “RTAuto” mean in the upper right corner of the screen, which appears when you long press the Auto button.
P.S. I wanted to send images of my board and "RTAuto", but I couldn't. How can I send an image here when replying to a post?

5

Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD

« Last post by Performa01 on Today at 08:10:31 am »

I have been wondering whether Performa01 might have had a hand in some parts of the SDS800X HD manual (and prior manuals for the same platform). There are some chapters which are a touch above the rest -- say the FFT chapter, and some paragraphs in the Math/Filter section.

Anybody able to offer insights? Just curious... 

I think I'm the best person to answer this: no, I've never consciously contributed to any Siglent manual, I've not even ever reviewed one.

I've always tried to use the instruments intuitively, and only if that failed took a look at the manual - which were very rare cases. Of course, if I found the information there to be incorrect or missing, then I've reported it.

Why did I write "consciously" in the paragraph above? No, I'm not a somnambulist, but I've published a lot of things in this forum, including a deep review of the SDS1004X-E, which might have had some influence one way or the other.

6

Test Equipment / Re: Hacking the Rigol DHO800/900 Scope

« Last post by shapirus on Today at 08:07:29 am »

All this separate work really needs a github repo to track. If not for direct use for the recompilation of the .apk, then at least as a source to make diffs against and patch your own decompiled .apks.

7

Beginners / Re: SOURCE CODE of BSIDE01 : WHERE I CAN DOWNLOAD IT ?

« Last post by gnif on Today at 07:59:21 am »

I have done this anyway.

8

Beginners / Re: Calibration - How to Mathematically

« Last post by Picuino on Today at 07:52:45 am »

It depends. What function do you want to approximate and with what accuracy?

9

Projects, Designs, and Technical Stuff / How do hall effect switches not oscillate at the crossover point?

« Last post by e100 on Today at 07:42:01 am »

I had run out of Allegro A3144 hall effect switches so I tried to make a similar thing using two 3503 linear hall sensors feeding into the differential AB inputs of a Max485 chip in receive mode.
I waved a magnet in front of one sensor and assumed that the 200mV hysteresis would give a clean signal, but instead I see a series of spurious pulses before it finally flips state.

Do real hall effect switches have the same problem internally, but just capture the first pulse and stretch it out to meet the fully flipped state?
The datasheet for the A3144 doesn't really explain what it does internally, other than showing a Schmitt trigger block.

10

Repair / Re: Tektronix DPO4054 stucked at tektronix splash screen

« Last post by ApertureScience on Today at 07:40:29 am »

I now have error messages regarding DramDqPullUpStrength and DramDqPullDownStrength. Im considering putting the old ram chips back and maybe diong a complete reball of U370.