Author Topic: Test equipment is a disease...  (Read 4361 times)

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Online tggzzz

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Re: Test equipment is a disease...
« Reply #25 on: July 17, 2024, 02:22:31 pm »
I have at my disposal no less than 4 wonderful pro-level bench power supplies.

Only 4?  ::)

You need 4 before you can get 5 :)

The same is true for oscilloscopes.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Online tggzzz

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Re: Test equipment is a disease...
« Reply #26 on: July 17, 2024, 02:23:22 pm »
Help me!

The first step in self-help is to realise an addiction is not a disease.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline TomKatt

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Re: Test equipment is a disease...
« Reply #27 on: July 17, 2024, 02:26:31 pm »
It's not mine - I'm just testing it for a friend!
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Offline BillyOTopic starter

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Re: Test equipment is a disease...
« Reply #28 on: July 17, 2024, 02:38:34 pm »
The same is true for oscilloscopes.
Oh heck, I have 10 11 of those...
Bill  (Currently a Siglent fanboy)
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Offline TomKatt

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Re: Test equipment is a disease...
« Reply #29 on: July 17, 2024, 02:42:01 pm »
The only thing keeping my house looking like Mr. Carlson's lab or Curious Marc is my home isn't large enough.

And the wife claims she needs to eat.  :P
Several Species of Small Furry Animals Gathered Together in a Cave and Grooving with a PICt
 
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Offline exe

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Re: Test equipment is a disease...
« Reply #30 on: July 17, 2024, 02:57:51 pm »
Could somebody explain the dangers of connecting power supplies in series? Apart from lethal output voltage.

Afaik, some measurement equipment mentions that isolated outputs can only float above ground up to some voltage (e.g., 240V). Can this be a problem with this setup?
 
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Online tggzzz

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Re: Test equipment is a disease...
« Reply #31 on: July 17, 2024, 03:03:40 pm »
Could somebody explain the dangers of connecting power supplies in series? Apart from lethal output voltage.

Afaik, some measurement equipment mentions that isolated outputs can only float above ground up to some voltage (e.g., 240V). Can this be a problem with this setup?

Potentially, yes. That will be clearly stated in TFM (which you will have read, of course) and possibly on the front or back panel.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 
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Offline AVGresponding

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Re: Test equipment is a disease...
« Reply #32 on: July 17, 2024, 04:04:09 pm »
But have you connected all the ports in series yet? :)
There's some great potential there! :-DD

 :palm:   :-+
nuqDaq yuch Dapol?
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Offline armandine2

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Re: Test equipment is a disease...
« Reply #33 on: July 17, 2024, 05:46:19 pm »
connecting in series - from the manual
In a closed society where everybody's guilty, the only crime is getting caught - Hunter S Thompson
 
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Offline Njk

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Re: Test equipment is a disease...
« Reply #34 on: July 17, 2024, 06:48:54 pm »
IMHO, now the situation is that each new model is less useful than the previous. Because one thing that makes the instrumentation equipment special is that a good knowledge about how the instrument works is required to use it successfully. Indeed, how I can trust the number if I don't know how it's obtained.

That's very obvious and in the past every instrument was accompanied by a large documentation volume, that explained not only how to operate the instrument but also provided great details about what's inside, up to the wiring diagram and BOM. Because it's all necessary for customer. Now it's considered a secret information and only the magic box is provided. That's ridiculous. After all, the illegal taxi drivers at the airport are also fiercely competing each other but they're typically smart enough to don't load the customer with their problems. If it's so confidential, the best thing the vendor shall do is to don't sell the instrument. Just keep it for himself and be happy.

Moreover, the fact that there is no widespread rebellion against this trend in the professional community suggests that now few EEs are actually interested in knowing what exactly they're doing. The majority are within a hierarchy and are doing just what they told to do. Perhaps that's OK but that makes their products not trustworthy as well.
 
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Online tautech

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Re: Test equipment is a disease...
« Reply #35 on: July 17, 2024, 08:40:32 pm »
Test equipment is a disease...



And your nowt but a super spreader
Much prefer enabler.   :)
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Some stuff seen @ Siglent HQ cannot be shared.
 
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Online tautech

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Re: Test equipment is a disease...
« Reply #36 on: July 17, 2024, 08:49:00 pm »
Could somebody explain the dangers of connecting power supplies in series? Apart from lethal output voltage.

Afaik, some measurement equipment mentions that isolated outputs can only float above ground up to some voltage (e.g., 240V). Can this be a problem with this setup?
Internal breakdown/flashover clearances and component ratings determine how many units can be placed in series.

Ratings such as follows give indications of how high you can push series connections:
Insulation
Case to Terminal ≥ 20 MΩ (DC 500 V)
Case to AC line ≥ 30 MΩ (DC 500 V)
Avid Rabid Hobbyist.
Some stuff seen @ Siglent HQ cannot be shared.
 

Offline Martin72

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Re: Test equipment is a disease...
« Reply #37 on: July 17, 2024, 11:33:08 pm »
Hi,

Quote
Internal breakdown/flashover clearances and component ratings determine how many units can be placed in series.

That was not the idea behind it, the aim is to reliably separate input and output potentials.

Quote
Ratings such as follows give indications of how high you can push series connections:
Insulation
Case to Terminal ≥ 20 MΩ (DC 500 V)
Case to AC line ≥ 30 MΩ (DC 500 V)

These are insulation values against the housing(GND), which has nothing to do with how far you can push the series connection.
The 500V is the test voltage.
On the one hand, it is about the sufficient insulation of active circuits against the housing (contact), and on the other hand about the leakage current that results from the EMC capacitors at the input/output against the housing.










 
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Offline CatalinaWOW

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Re: Test equipment is a disease...
« Reply #38 on: July 18, 2024, 12:08:37 am »
In theory connecting isolated outputs from multiple supplies in series doesn't cause any issues.  But in the real world there is often a sneak circuit connecting something you are powering with that series question to ground, and then the mischief happens.  Some people are more careful than others.  Those of us who slip up once in a while like to put an extra layer of protection to cover our occasional lapses.  And thus tend to avoid this type of series connection.
 

Online tautech

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Re: Test equipment is a disease...
« Reply #39 on: July 18, 2024, 01:10:35 am »
Hi,

Quote
Internal breakdown/flashover clearances and component ratings determine how many units can be placed in series.

That was not the idea behind it, the aim is to reliably separate input and output potentials.
And how does the highlighted above not do that ?  :popcorn:
Quote
Ratings such as follows give indications of how high you can push series connections:
Insulation
Case to Terminal ≥ 20 MΩ (DC 500 V)
Case to AC line ≥ 30 MΩ (DC 500 V)
Quote
These are insulation values against the housing(GND), which has nothing to do with how far you can push the series connection.
The 500V is the test voltage.
On the one hand, it is about the sufficient insulation of active circuits against the housing (contact), and on the other hand about the leakage current that results from the EMC capacitors at the input/output against the housing.
So, just the same as any other device we use and you push near it at your own risk.  :scared:

If we are discuss what can be done with specific models, sure let's do that.
FYI series connections of multiple SPD3303X when in Series mode is a HQ endorsed use type.

A few years back from the HQ App engineer:
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Offline 44kgk1lkf6u

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Re: Test equipment is a disease...
« Reply #40 on: July 18, 2024, 02:12:03 am »
Whoever spends too much on test equipment should learn from the guy at Siglent.  He does not even want to waste money on proper cables.  Not even when it may give the customer a bad impression.
 

Offline pdenisowski

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Re: Test equipment is a disease...
« Reply #41 on: July 18, 2024, 08:25:13 am »
Could somebody explain the dangers of connecting power supplies in series? Apart from lethal output voltage.

Afaik, some measurement equipment mentions that isolated outputs can only float above ground up to some voltage (e.g., 240V). Can this be a problem with this setup?

Yes, that's exactly the issue - max voltage to ground.  I talk about this in my video

https://youtu.be/o7uxeRjJsMk?t=110

Test and Measurement Fundamentals video series on the Rohde & Schwarz YouTube channel:  https://www.youtube.com/playlist?list=PLKxVoO5jUTlvsVtDcqrVn0ybqBVlLj2z8
 
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Offline pdenisowski

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Re: Test equipment is a disease...
« Reply #42 on: July 18, 2024, 08:26:48 am »
There's some great potential there! :-DD

Shocking!  :-DD
Test and Measurement Fundamentals video series on the Rohde & Schwarz YouTube channel:  https://www.youtube.com/playlist?list=PLKxVoO5jUTlvsVtDcqrVn0ybqBVlLj2z8
 
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Online Smokey

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Re: Test equipment is a disease...
« Reply #43 on: July 18, 2024, 09:05:09 am »
I have no immediate need for the Advantest SMU I just picked up. 

I have at my disposal no less than 4 wonderful pro-level bench power supplies.

Only 4?  ::)

If you count that as a power supply, I'm up to 12ish power supplies throughout the whole lab :)
 
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Offline m k

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Re: Test equipment is a disease...
« Reply #44 on: July 18, 2024, 09:36:28 am »
I have at my disposal no less than 4 wonderful pro-level bench power supplies.  A pretty good low end unit and a fairly nice DIY one I just finished building.

Guess what I spent all day on today?  Yup, designing an even better DIY bench power supply!!!

Help me!

[secret four knee trochee mumbling]
That's a spell of help.
It works just like usual helping spells do.

BTW,
how many noble gas filled glass tubes it has?
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 

Offline shakalnokturn

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Re: Test equipment is a disease...
« Reply #45 on: July 18, 2024, 11:45:50 am »
Could somebody explain the dangers of connecting power supplies in series? Apart from lethal output voltage.

Afaik, some measurement equipment mentions that isolated outputs can only float above ground up to some voltage (e.g., 240V). Can this be a problem with this setup?

Depending on current capabilities / adjustments of protagonists and user abuse there's also the risk of killing the reverse polarity protection diode in the weaker supply.
(Don't ask... I'm an abusive user with about a dozen power supplies, lack of bench causes me to use the most basic 2.5A 30V model most of the time though.)
 

Offline BillyOTopic starter

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Re: Test equipment is a disease...
« Reply #46 on: July 18, 2024, 02:36:05 pm »
BTW,
how many noble gas filled glass tubes it has?

None yet...
Bill  (Currently a Siglent fanboy)
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Offline voltsandjolts

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Re: Test equipment is a disease...
« Reply #47 on: July 18, 2024, 04:38:38 pm »
I might be into the second stage of TE syndrome.
I seem to only buy broken gear, even when the backlog of repairs I already have would keep me busy for the next few months.

Why is this happening to me?
 

Offline TomKatt

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Re: Test equipment is a disease...
« Reply #48 on: July 18, 2024, 04:44:56 pm »
I might be into the second stage of TE syndrome.
I seem to only buy broken gear, even when the backlog of repairs I already have would keep me busy for the next few months.

Why is this happening to me?
Where's the fun if something just works ???
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Offline BillyOTopic starter

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Re: Test equipment is a disease...
« Reply #49 on: July 19, 2024, 02:30:20 am »
Where's the fun if something just works ???
Can't even imagine what that'd be like!   :-DD
Bill  (Currently a Siglent fanboy)
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