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Test Equipment / Re: Siglent SDS2000X Plus vs SDS2000X HD
« Last post by Electro Fan on Today at 11:06:48 pm »
I could talk about the two models now, as I have owned both - but why are you opening a new thread?

Hi Martin,

Which thread would you recommend?  Thx, EF
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Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD
« Last post by Lexy on Today at 11:02:34 pm »
It doesn't look like eleshop is an official siglent distributor, on their german website siglent is not even listed as a brand.
Such stores are the last to be supplied.
So I'm a little surprised why you're ordering there.
But they did come up with a nice gag:
Quote
Siglent is a fast growing brand. The qualities and construction structure of Siglent products are comparable to top brands, such as Rigol, while the prices are often very competitive.

 :-DD

Eleshop is listed at the Siglent EU site as 'Siglent Authorized Distributor' : https://www.siglenteu.com/how-to-buy/

But i bought several test equipment from the Eleshop, so that's why i order the SDS3034X HD here.

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I have a project with two SIC451 buck converters, the output on both of them is oscillating, and I'm trying to figure out why.

The regulators are 12V to 5V and 12V to 3.3V at 15-25A. The design is very space constrained so the switching frequency is set as high as possible at 1.5MHz to minimize the number of output caps and the inductor size.

The oscillation is 1.8v p-p at 100kHz around the output voltage setpoint of 5V. My calculations indicated the minimal output capacitance I used should have been enough to meet my ripple target, taking the DC bias effect into account. I've found that adding more output capacitance makes the regulators stable, although the 5V regulator is still being stubborn. On the 5V regulator I've increased the output caps from 2x 10uF to 11x 10uF 0805 X7S MLCC caps and it will still sometimes start oscillating after a 1A to 20A load step at 2.5A/us. Sometimes it will start oscillating and then stop after a second. Before adding the additional caps, both regulators would start oscillating immediately after turn-on. The 3.3V regulator was stable after increasing the output caps from 2x 10uF to 5x 10uF.

It's odd because the 2x 10uF caps I started with were enough to hit my output ripple target. I can tell because I could connected a 2200uF aluminum polymer across the output to stabilize it, then remove it, and the output ripple would be fine until it started oscillating a second or two later again. The datasheet even says "The device has integrated internal compensation and is stable with any type of output capacitor."

In my initial testing with just 2x 10uF output caps, I found adding the 2200uF 8 mOhm ESR aluminum polymer cap across the output would make it stable, or adding several 10uF MLCCs would make it stable, but a 68uF 250mOhm ESR electrolytic didn't help at all. This implies a low ESR is necessary.

When I power the board from the big high current PSU that will be used in the actual application, rather than my bench PSU, the board seems more stable.

Has anyone seen anything like this before? Is it just insufficient output capacitance? Could this be some weird interaction with my bench PSU and poor input wiring powering the board?




In the schematic, you'll see the SIC451 supports differential remote voltage sense and there is an appnote that recommended a filter to reduce jitter. This is the 1R and 2.2uF shown on the 5V output and GND. I have removed the 2.2uF capacitors in case they were causing some sort of feedback issue but there was no improvement. The remote sense lines are currently disconnected so the feedback is coming through the 220R resistors.

The attached scope shot shows the output starting to oscillate after a load step. This is the 5V regulator with 8x 10uF MLCCs on the output.
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Beginners / Re: Help identifying some (likely older) compontents.
« Last post by wraper on Today at 11:00:06 pm »
https://www.diyaudio.com/community/threads/help-me-identify-a-mysterious-device-and-a-resistor-type.406656/
Someone said:
Quote
the metal case ones are high temp metal film no drift type used in radar.
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Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD
« Last post by Martin72 on Today at 10:58:21 pm »
Hmm....
They also tolde me the thing with the 1000X HD, but not this:
"they said that they couldn't say anything about it"

OK, let´s be patient and wait and see...
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Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD
« Last post by egonotto on Today at 10:56:17 pm »
Hi egonotto,
If you're referring to the 3034X HD, they told me(yesterday) that they can't guarantee it BEFORE Easter because they expect it next week.
They themselves are a bit upset because they actually wanted to take a 3000 to the trade fair stand.

Hello,

if I remember the chat correctly, when I asked about my SDS3034X HD order, they said that they couldn't say anything about it and that they had at least received a few SDS1000X HD today.

Best regards
egonotto
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General Technical Chat / Re: Baltimore Francis Scott Key Bridge collapse
« Last post by Someone on Today at 10:55:05 pm »
At least it's not on fire.
Yet/so-far.
Why would you expect this to happen, given that no indications so far point towards anything even distantly fire-related. The Dali is now at rest, and ships at rest don’t normally just burst into flame.

The two sources of smoke initially reported by some have since been explained: the black smoke is from the engines, and the “smoke” at the point of impact is concrete dust, isn’t it?
Mostly in jest, but grounded ships have subsequently caught fire in the past so its not implausible.
I said ships do not normally catch fire, not that it's impossible.

And it's not grounded, mind you. The ship is afloat.
Equally I'm not saying it will catch on fire in the future for certain. yet/so-far both leave either possibility for the future and literally mean "up to the current time".

As to grounded, if it cant move as its tangled in things sitting on the riverbed, that mass/agglomeration of which the ship is a part is grounded.
Wikipedia references bringing the goods:
https://maritime-executive.com/article/bridge-s-weight-is-pinning-container-ship-dali-to-the-bottom
Quote
In a reversal of the usual order for a major marine salvage operation, the U.S. Army Corps of Engineers (USACE) and its contractors will make the first big move in getting the wrecked container ship Dali out of Baltimore's ship channel.

Dali's bow is technically aground in the channel, said Vice Adm. Peter Gautier at a press conference Wednesday, because of the vast weight of the steel bridge span resting on top. The ship is pinned to the bottom and cannot move.
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Test Equipment / Re: EEVBlog 121GW Discussion thread
« Last post by thm_w on Today at 10:52:06 pm »
It would be nice if Shopify could just remove the country from the list to make it obvious that they won't accept shipments there.

If you want to be a dick you can order via Ebay, where Dave has not restricted it yet. But I would not do that lol
https://www.ebay.com/itm/223244201244
"Excludes:
Afghanistan, Anguilla, Belarus, Bolivia, Botswana, Central African Republic, Chad, Comoros, Djibouti, Ecuador, El Salvador, Guinea-Bissau, Guyana, Libya, Madagascar, Moldova, Mongolia, North Korea, Reunion, Russian Federation, Rwanda, Sierra Leone, Somalia, Suriname, Svalbard and Jan Mayen, Syria, Trinidad and Tobago, Tunisia, Venezuela, Yemen"

Cost for me is about $37 to ship to Jordan via UPS. DHL is $68. But customs can be hell even if shipping cost is reasonable.
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Test Equipment / Re: Hacking the Rigol DHO800/900 Scope
« Last post by Mechatrommer on Today at 10:51:51 pm »
The following is the logical pseudocode for a few key functions:
so the RK3399 pins 122-126 are set as output, and then later stage  gpio_afg_drv_read read them as if they are input? hmm confusing... ;D
You can read the state of any gpio state, does not matter of they they are in or out pins, or digital or analog.
If someting reads the pin states (digi), then that's usually to verify what they are because it's possible some parts of the code somewhere could have changed them.
ok, so if reading is only to verify output pin's state (whether its outputtting HI or LO), then its not to verify whether AFG HW exists or not. correct? btw, i managed to rev eng the pin interface is due to FPGA is outputting valid AFG signal naked on bright day even if no AFG HW presents, and i didnt manage to hang anything during the process. so maybe people who reported hanging their dso while playing with AFG GUI did something else to cause the hang? maybe they activate bode plot? and hence dso struggled to find signal on CH1 and CH2?
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Test Equipment / Re: Siglent SDS2000X Plus vs SDS2000X HD
« Last post by Martin72 on Today at 10:44:08 pm »
I could talk about the two models now, as I have owned both - but why are you opening a new thread?
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