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I would expect the highest cost meter to be one of the most robust.

I totally agree with you ;-) As you pay more for the device it should be well designed and made!
Its very annoying if it isnt, since the "law" of economy says, you get what you pay for! But unfortunately in our money driven World to many players try to optimize their profits instead of their products.
Not necesarily. Long scale benchtop meter are not robust at all. They have other priorities. I believe same is here. MTX 3293 is for electronics, in the lab. It's robust enough for that.  Also, no, I don't hit it with a hammer or play football with it. So it will last.
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Repair / Re: Sony a7R ii Missing component identification
« Last post by LateLesley on Today at 04:43:25 pm »
While I can't help with the component ID (it's hard to tell with these things), I did find a datasheet for the chip it's beside. I'm thinking if you can trace tracks from the chip, it may offer clues to what the missing part is, from the example circuit??

http://www.ti.com/lit/ds/symlink/tps63060.pdf

Page 12 is the example circuit, page 3 is the pinout.
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Buy/Sell/Wanted / Re: WTB: Tektronix TDS210/220 LCD
« Last post by kayvee on Today at 04:42:30 pm »
I don't want to spend too much, hence the word scavenge above . ^-^

Or I could go get a Chinese replacement for around $50.

After seeing another one on ebay afflicted with the same plight as mine:

https://www.ebay.com/itm/Tektronix-TDS-210-Two-Channels-Digital-Oscilloscope-60MHz-1GS-s-Part-94585/153355208776?epid=96937615&hash=item23b4aec848:g:78gAAOSwdqNcTnVh&frcectupt=true

I am thinking possibly a new replacement may be the better option, but it's unusable in it's current condition.
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Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread
« Last post by 0culus on Today at 04:38:03 pm »
I'm glad my 'scopes don't glow (other than the phosphor)  :o

https://vintagetek.org/radioactive-scopes/
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Thank you guys!!!
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Projects, Designs, and Technical Stuff / Re: Open HV Probe 40kV
« Last post by tggzzz on Today at 04:35:26 pm »
For comparison, here's my 40kV meter. Tip to disc is 13cm, disc diameter is 7cm

I picked it up cheaply, and haven't had occasion to use it at more than a too small fraction of its rated value.

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Projects, Designs, and Technical Stuff / Re: Open HV Probe 40kV
« Last post by tggzzz on Today at 04:25:56 pm »
What material are you using?

Is it in any way hygroscopic over time?

Can oils/grease/etc lodge on the surface and be difficult to remove?

At 40kV it might be necessary to be careful of those points, but those questions are worth what you pai for them.

True of fairly much all plastics and especially with HV. Regardless of commercial or home made care with oils and water is a must do. I am planning to use PLA on mine but ABS would be fine too, PETG I have never seen any tests done on it but it is better with moisture then PLA for example but I am uncertain of it's electrical characteristics.

The fabrication technique may also be relevant, in particular the body will not be smooth and will not be solid. Both of those may trap undesirable water/oil/etc.

Quote
Long term keep it clean and dry and if in doubt print another.

I always have doubt, so that wouldn't help me!

Sorry, I don't feel like spending 40 minutes of my remaining life looking at those videos. (Especially since almost all yootoob vids are talking heads and I can speed read much faster than I can watch videos)
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Metrology / Re: LTC6655B long term drift
« Last post by alex-sh on Today at 04:20:54 pm »
Hello,

So you are fixed to the LTC6655 because it has a unique pinning (force + sense)
Dont get me wrong: the LTC6655 is not really bad. But you cannot expect 5-6 digits accuracy in MSOP.
Its more like 4-5 digits. (as long as you do not apply force to the PCB).
By the way the LTC6655 has high current consumption and so heats up rather high.
Did you keep air drafts away from it?

That does not explain why you need the 4.1V reference.
(you do not really want to make a 1mV step calibrator with a 12 bit DAC).

The best results (hysteresis + humidity stability) up to now I have with the AD586LQ (5V) and AD587JQ (10V)
But for high demands you have to select for tempco and ageing.

The next best device for 4.1V could be a MAX6341. (if you have >=8V stabilized supply voltage).
But all my MAX6250A and MAX6350 (5V in DIP8) from the same series have around 10 ppm/year ageing drift.
And also on many samples I see popcorn noise of 1-2 ppm near certain temperatures.

Thank you Andreas
My expectation is not meeting reality I suppose. I was hoping for 5-6 digits accuracy, but with LTC6655 I am disappointed. Good initial results, but very poor long term performance.
Yes, the design of the PCB takes in the account that the vref may heat up and it is isolated away from the rest of the components.
I am using AD5541LRZ (16 bit DAC) and have 1mV steps from 1mV to 4096mV with ability of 60uV calibration steps. I'll look into this, but I think 4.096V vref is not critical. The problem is that the vref is fed from +5V power rail and this means using 5V vref would not be possible without modifying or adding a new power rail.
AD586LQ would be a good one if the design was catering for 10.8V ~ 36V input voltage.
I also have MAX6341CPA+-ND in DIP8 - this means I can use it on the daughter board with a few caps. I can probably live with +/- 40uV / year drift.

I suppose I should think what to do next.
Thanks
Alex
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General Chat / Re: Fake $9 Chinese Intel 8087 chip from eBay
« Last post by cjs on Today at 04:20:08 pm »
A dictator can request his people not to buy imported goods unless necessary, while a free market leader can't, so the dictator can shift money to where it's needed and run the economy more efficiently.

Actually, technically that's running economy less efficiently because you're either not buying the optimimum goods for what you need to do or you're paying more than you need to for them. Generally, avoiding trade reduces economic efficiency.

That's not to say that there aren't good reasons to take the efficiency hit, such as you want to build the skills and infrastructure to create certain items in your own country rather than having to buy them. Or when you trade for certain things, the economic gains go just to the rich who won't give any of that to the poor, and more optimal means of making sure poor people aren't worse off are rejected for reasons unrelated to economic efficiency.

(Yes, this is surely getting off topic here, but I'm not sure the whole thread is on any kind of reasonable topic anyway.

(And, "request." I don't think that's quite the right word for what dictators do. :-))
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Test Equipment / Re: Cheapest touchscreen Oscillorscope?
« Last post by exe on Today at 04:14:40 pm »
For desktop, definitely don't get a MicSig. It's less capable (no active probe I/F, which is very important in my daily works)

I don't know what is I/F, but I don't see what micsig is really missing from "desktop" oscilloscopes in the same price range. A good active probe costs more than this small device. Don't compare it with MSOX3054A ;).

I use it as a desktop oscilloscope and I'm quite happy about it. It's not ideal, the screen is glossy, the stand is not adjustable, the fan is a bit more loud than it should, UI is a bit slow (still faster than R&S!), but it does the job.
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