EEVblog #1304 - Mailbag

[EEVblog]

SPOILERS:

SDS2000X Plus Series Digital Phosphor Oscilloscopes
https://siglentna.com/products/digital-oscilloscope/sds2000xp-series-digital-phosphor-oscilloscope/

5:33 Otur 15W Laser Engraver:
https://s.click.aliexpress.com/e/_d9lWRLx
https://s.click.aliexpress.com/e/_d6cHmFB

17:59 Practical Audio Electronics Book + Sharp Calculator
https://amzn.to/2YAm76g

29:07 555 Sticker Book

31:44 Quitech Otti USB power measurement and battery analyser: https://www.qoitech.com/

1:04:00 USB cable checker: Is it me, or is it USB? Tindie: https://www.tindie.com/products/nerfhammer/is-it-me-or-is-it-usb/

1:06:13 Trump 2020 bucks

[DrG]

It's practically guaranteed?? 

[johnlsenchak]

Differently   want to  see  a tear  down on that Siglent  SDS2000X Plus Series r Oscilloscopes

Trigonometry  is  the best math     ! 

You should   use that laser printers to  make  EEVblog  logos   on badges  that people  can magnetically  stick  on things

Huxley  is  awesome    !

[Jeff1946]

Warning.  The laser in the engraver could easily damage your retina even from a reflection.  Proper eye protection is a must.  I have known people who have small blind spots from that kind of an accident.

[thm_w]

Warning.  The laser in the engraver could easily damage your retina even from a reflection.  Proper eye protection is a must.  I have known people who have small blind spots from that kind of an accident.

To add to this, don't rely on the glasses they have included. They may be garbage.
Either buy a known good pair of glasses or put the whole laser in a safe enclosure (eg black acrylic, or some other opaque material).

https://www.youtube.com/watch?v=upCsVrKrW7M

[Brumby]

I was waiting for you to scorch that mat....

[WackyGerman]

What a really huge t-shirt . You can buy some poles and stakes , go in the garden for an outdoor overnighter  with this 

[Howardlong]

I just ordered one of these Qoitech otii??? things and it arrived today. That UI might look nice but not much is intuitive. What is it with UI designers nowadays, do they expect you to randomly push buttons until it works?

Even the website you have to check a box off to the upper right before you can download the software.

One possible mistake I made was to try to upgrade the firmware, but the process seemed to hang. Then there were no readings at all, the graphs scrolled but were blank. "Turned it off and on again" and things seemed to be better, but not only is the UI ambiguous, the nomenclature around the various measurements isn't straightforward either.

I hooked it up to a Keithley SMU and did a few low current measurements sub uA and it seems very noisy with the highest 22 ohm sense resistor, but that was with just ten minutes of fiddling.

I want to like it, I really do. Just there's very little that's intuitive to me right now. I can totally understand why Dave was fighting with it too.

[thm_w]

Why would you buy an otii if you have a SMU already?
Or is it an old school one lacking in comms.

[Howardlong]

Why would you buy an otii if you have a SMU already?
Or is it an old school one lacking in comms.

The two SMUs I have are GPIB, Keithley 236 and 238, not really that useful if you're trying to sniff out quick low duty cycle events. They also lack the dynamic range I'm after.

I have been working on my own solution for the coin cell devices I work on that uses logarithmic amplifiers originally designed for use with photodiodes. Even with my breadboarded designs I can get these these measure from single digit mA down to sub nA with reasonable speed and accuracy, but you need to take special care with how you do measurements under a few uA.

[wernerj]

I just ordered one of these Qoitech otii??? things and it arrived today. That UI might look nice but not much is intuitive. What is it with UI designers nowadays, do they expect you to randomly push buttons until it works?

I'm mainly working on the hardware and firmware parts of otii but feedback and questions are always very welcome at support@qoitech.com, this will help steer further development in the right direction.

I hooked it up to a Keithley SMU and did a few low current measurements sub uA and it seems very noisy with the highest 22 ohm sense resistor, but that was with just ten minutes of fiddling.

I want to like it, I really do. Just there's very little that's intuitive to me right now. I can totally understand why Dave was fighting with it too.

Yes there's measurement noise present when looking at individual samples, it's always a tradeoff. I'm curious about roughly how much noise you saw in the recordings? The measurement noise should be around +/- 0.5uA peak-to-peak. Some users wants to measure fairly low duty cycle signals, some are only interested in long-term averages but we want to capture as much information as possible. Measurement of the average signal can be performed either while still recording or after you have finished recording, performing a selection will immediately update the statistics in the top right corner of the graph. After the recording is stopped it can also be downsampled if a lower data rate is desired, this will reduce the peak-to-peak noise.

[CChin254]

Quitech Otti IC Identification and Manufacturer Breakdowns:
Note I had this lying around for a while and IDK why I haven't posted yet so there could be errors in this.