Test equipment is a disease... - Page 1
Forum section: electronics / testgear

author: BillyO
author_rank: Super Contributor
timestamp: July 16, 2024, 11:05:40 pm
content: 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!

author: TomKatt
author_rank: Frequent Contributor
timestamp: July 16, 2024, 11:10:44 pm
content: Don't look at me for help - I got curious why I was having trouble plugging a differential probe into the usb port of my scope for power and now I'm building a current probe setup to investigate something that could be solved simply by plugging it into a wall wart... Meanwhile my original task gets completely sidelined and my online shopping carts are filling up with new gear.It never ends ;-)

author: Martin72
author_rank: Super Contributor
timestamp: July 16, 2024, 11:16:01 pm
content: Hi BillyO,https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/Edit: Bla.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: July 16, 2024, 11:22:32 pm
content: Re: "how much power can I get out of a scope USB port to power my probe," I was measuring exactly this just the other day by using my N6705B as a fancy graphing electronic load.https://www.dropbox.com/scl/fi/n668g389bo57tq4e5ogu8/Probe-Pwr.pdf?rlkey=9ysljk45tm4tg444gzu9sgv1o&st=r7l5gds9&dl=0so clearly you should just buy more equipment. What's that? You aren't made of money? Well there's a "cheap" and "broken" (i.e. "adventure model") one on eBay right now! Hurry hurry hurry! Just think of all the money you could saaaaaaavvvveeeEDIT: ebay link removed due to compliance with Test Equipment Voluntary Self-Exclusion Program

author: TomKatt
author_rank: Frequent Contributor
timestamp: July 16, 2024, 11:28:02 pm
content: Quote from: jjoonathan on July 16, 2024, 11:22:32 pmNot to derail the topic, but thanks! Very interesting - I cannot believe I'm going over an amp... Clearly I've got more investigating to do lol.And don't tempt me like that !!!

author: jjoonathan
author_rank: Frequent Contributor
timestamp: July 16, 2024, 11:34:32 pm
content: The overcurrent protection is pretty quick, it might have triggered on inrush surge. The USB chip on my scope (USB2517, the proprietary probe interface is just USB + 2 pins) supported the following timings:Code:5:4 OC_TIMER Over-Current Timer: Over-Current Timer delay.00=0.1ms01=4ms10=8ms11=16msYou can see from my measurements (17.8ms cutout) that it was programmed to the longest delay, not shortest.

author: Martin72
author_rank: Super Contributor
timestamp: July 16, 2024, 11:39:26 pm
content: Guys, things are getting a bit wild here...Edit: Bla.

author: TomKatt
author_rank: Frequent Contributor
timestamp: July 16, 2024, 11:40:15 pm
content: Quote from: Martin72 on July 16, 2024, 11:39:26 pmIt's a disease!

author: jjoonathan
author_rank: Frequent Contributor
timestamp: July 16, 2024, 11:46:18 pm
content: It's not the polychlorinated compounds in my brain speaking, it's the practical time savings on every occasion I have to make dynamic power measurements... on another piece of test equipment

author: EEVblog
author_rank: Unknown
timestamp: July 17, 2024, 12:11:32 am
content: Quote from: BillyO on July 16, 2024, 11:05:40 pmOnly 4?

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2024, 12:19:54 am
content: Quote from: Martin72 on July 16, 2024, 11:39:26 pmThat obviously doesn't matter if even the “boss” is involved.Accordingly, I withdraw my previous posts.

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2024, 12:31:15 am
content: Test equipment is a disease...And you are blind without it !Some of us are fortunate to live, eat and breathe it.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 17, 2024, 12:46:07 am
content: But no piece of gear does everything perfectly, and there is always that one measurement you can't quite do right or easily with what you have at hand.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2024, 01:25:32 am
content: Or you buy an SPD3303X that you didn't need, and find out it's the older problematic hardware so now you want to buy an electronic load to test while it's still in warranty.

author: EEVblog
author_rank: Unknown
timestamp: July 17, 2024, 03:29:00 am
content: Quote from: KungFuJosh on July 17, 2024, 01:25:32 am

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: July 17, 2024, 03:54:04 am
content: Quote from: BillyO on July 16, 2024, 11:05:40 pmHey, as long as you post about it (inc schematics), then you can honestly say that you're taking one for the team -- and loving it!

author: BillyO
author_rank: Super Contributor
timestamp: July 17, 2024, 04:26:19 am
content: Quote from: EEVblog on July 17, 2024, 12:11:32 amI know, I suck. Hey, I've only been at this since my 2nd retirement 2 years ago!!!Now I'm taking on jobs again..I'll never learn.

author: BillyO
author_rank: Super Contributor
timestamp: July 17, 2024, 04:31:34 am
content: Quote from: KungFuJosh on July 17, 2024, 01:25:32 amDid that already...

author: BillyO
author_rank: Super Contributor
timestamp: July 17, 2024, 04:32:33 am
content: Quote from: Martin72 on July 17, 2024, 12:19:54 amI enjoyed the first one for at least 10 pages..

author: BillyO
author_rank: Super Contributor
timestamp: July 17, 2024, 04:37:25 am
content: Quote from: ballsystemlord on July 17, 2024, 03:54:04 amWe'll see how the prototypes work out. Never like to bend over with my knickers down!

author: artag
author_rank: Super Contributor
timestamp: July 17, 2024, 07:40:59 am
content: It's not just test equipmentWhen I'm holding your wheelAll I hear is your gearWhen my hand's on your grease gunOh, it's like a disease, son

author: moerm
author_rank: Regular Contributor
timestamp: July 17, 2024, 11:20:11 am
content: Quote from: BillyO on July 16, 2024, 11:05:40 pmSorry, can't, wrong address. Help from a guy who designed all his supplies, currently 8 (or 4 dual, plus a MV and HV one) himself? No way.You see, IMO one absolutelyneedsat least two dual low amp supplies plus a mid range one (3 or 4 Amps), all the usual range (30-ish V) plus, just in case, a dual >= 7 A (mine: 10 A), all linear as it befits a lab. Plus of course, a 500-ish V (abt 1 A), plus, being at it, a 10 x multiplier. All with a decent meter (14 bits).And I'm bloody sure that I'm still missing something.The culprit: An EE with lots and lots of experience whom I revered, who sternly told me that an electronician worth his salt builds his own PSUs when I asked him about a certain (commercial) PSU I intended to save for.

author: pdenisowski
author_rank: Super Contributor
timestamp: July 17, 2024, 12:01:23 pm
content: Quote from: BillyO on July 16, 2024, 11:05:40 pmQuote from: EEVblog on July 17, 2024, 12:11:32 amBut have you connected all the ports in series yet?

author: BillyO
author_rank: Super Contributor
timestamp: July 17, 2024, 01:55:39 pm
content: Quote from: pdenisowski on July 17, 2024, 12:01:23 pmThere's some great potential there!

author: themadhippy
author_rank: Super Contributor
timestamp: July 17, 2024, 02:15:25 pm
content: Quote from: tautech on July 17, 2024, 12:31:15 amAnd your nowt but a super spreader

author: tggzzz
author_rank: Super Contributor
timestamp: July 17, 2024, 02:22:31 pm
content: Quote from: EEVblog on July 17, 2024, 12:11:32 amYou need 4 before you can get 5The same is true for oscilloscopes.

author: tggzzz
author_rank: Super Contributor
timestamp: July 17, 2024, 02:23:22 pm
content: Quote from: BillyO on July 16, 2024, 11:05:40 pmThe first step in self-help is to realise an addiction is not a disease.

author: TomKatt
author_rank: Frequent Contributor
timestamp: July 17, 2024, 02:26:31 pm
content: It's not mine - I'm just testing it for a friend!

author: BillyO
author_rank: Super Contributor
timestamp: July 17, 2024, 02:38:34 pm
content: Quote from: tggzzz on July 17, 2024, 02:22:31 pmOh heck, I have1011 of those...

author: TomKatt
author_rank: Frequent Contributor
timestamp: July 17, 2024, 02:42:01 pm
content: 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.

author: exe
author_rank: Unknown
timestamp: July 17, 2024, 02:57:51 pm
content: 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?

author: tggzzz
author_rank: Super Contributor
timestamp: July 17, 2024, 03:03:40 pm
content: Quote from: exe on July 17, 2024, 02:57:51 pmPotentially, yes. That will be clearly stated in TFM (which you will have read, of course) and possibly on the front or back panel.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 17, 2024, 04:04:09 pm
content: Quote from: BillyO on July 17, 2024, 01:55:39 pm

author: armandine2
author_rank: Frequent Contributor
timestamp: July 17, 2024, 05:46:19 pm
content: connecting in series - from the manual

author: Njk
author_rank: Frequent Contributor
timestamp: July 17, 2024, 06:48:54 pm
content: 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.

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2024, 08:40:32 pm
content: Quote from: themadhippy on July 17, 2024, 02:15:25 pmMuch preferenabler.

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2024, 08:49:00 pm
content: Quote from: exe on July 17, 2024, 02:57:51 pmInternal 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:InsulationCase to Terminal ≥ 20 MΩ (DC 500 V)Case to AC line ≥ 30 MΩ (DC 500 V)

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2024, 11:33:08 pm
content: Hi,QuoteThat was not the idea behind it, the aim is to reliably separate input and output potentials.QuoteThese 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.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 18, 2024, 12:08:37 am
content: 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.

author: tautech
author_rank: Super Contributor
timestamp: July 18, 2024, 01:10:35 am
content: Quote from: Martin72 on July 17, 2024, 11:33:08 pmAnd how does the highlighted above not do that ?QuoteQuoteSo, just the same as any other device we use and you push near it at your own risk.If we are discuss what can be done with specific models, sure let's do that.FYI series connections of multiple SPD3303Xwhenin Series mode is a HQ endorsed use type.A few years back from the HQ App engineer:

author: 44kgk1lkf6u
author_rank: Regular Contributor
timestamp: July 18, 2024, 02:12:03 am
content: 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.

author: pdenisowski
author_rank: Super Contributor
timestamp: July 18, 2024, 08:25:13 am
content: Quote from: exe on July 17, 2024, 02:57:51 pmYes, that's exactly the issue - max voltage to ground. I talk about this in my videohttps://youtu.be/o7uxeRjJsMk?t=110

author: pdenisowski
author_rank: Super Contributor
timestamp: July 18, 2024, 08:26:48 am
content: Quote from: BillyO on July 17, 2024, 01:55:39 pmShocking!

author: Smokey
author_rank: Super Contributor
timestamp: July 18, 2024, 09:05:09 am
content: I have no immediate need for the Advantest SMU I just picked up.Quote from: EEVblog on July 17, 2024, 12:11:32 amIf you count that as a power supply, I'm up to 12ish power supplies throughout the whole lab

author: m k
author_rank: Super Contributor
timestamp: July 18, 2024, 09:36:28 am
content: Quote from: BillyO on July 16, 2024, 11:05:40 pm[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?

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 18, 2024, 11:45:50 am
content: Quote from: exe on July 17, 2024, 02:57:51 pmDepending 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.)

author: BillyO
author_rank: Super Contributor
timestamp: July 18, 2024, 02:36:05 pm
content: Quote from: m k on July 18, 2024, 09:36:28 amNone yet...

author: voltsandjolts
author_rank: Unknown
timestamp: July 18, 2024, 04:38:38 pm
content: I might be into the second stage of TE syndrome.I seem toonlybuy 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?

author: TomKatt
author_rank: Frequent Contributor
timestamp: July 18, 2024, 04:44:56 pm
content: Quote from: voltsandjolts on July 18, 2024, 04:38:38 pmWhere's the fun if something just works

author: BillyO
author_rank: Super Contributor
timestamp: July 19, 2024, 02:30:20 am
content: Quote from: TomKatt on July 18, 2024, 04:44:56 pmCan't even imagine what that'd be like!

author: asis
author_rank: Frequent Contributor
timestamp: July 19, 2024, 07:39:39 am
content: Quote from: pdenisowski on July 17, 2024, 12:01:23 pm.... and when you run out of wall sockets, you start rushing around - where to plug...And, you run into major troubles that can arise even due to the lack of contact in the grounding pin.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 19, 2024, 02:25:06 pm
content: If I connected all mine together in series, including voltage sources, it'd be up around 5kV. Probably not a great idea...

author: Martin72
author_rank: Super Contributor
timestamp: July 19, 2024, 02:45:58 pm
content: When you consider that anyone can call something like this, no matter how old or whether experienced/inexperienced...But at least the gene pool is kept in balance.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2024, 02:57:25 pm
content: Quote from: AVGresponding on July 19, 2024, 02:25:06 pmHow many amps?

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 19, 2024, 04:00:24 pm
content: Did the guy not figure out that he very likely internally shorted the cap?

author: tggzzz
author_rank: Super Contributor
timestamp: July 19, 2024, 04:01:18 pm
content: Quote from: AVGresponding on July 19, 2024, 02:25:06 pmMy single largest working PSU is 1kV 250W, a nicely limited electrophoresis PSU. Unfortunately the output is unacceptably noisy for my purposes, so I must get back to finding a way to reduce that noise.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 20, 2024, 01:46:05 pm
content: Quote from: Fungus on July 19, 2024, 02:57:25 pmGoing on the principle that the lowest current output is the limiting factor, I think 8mA, which is the maximum output of my LKB 2197 at 2.5kV, iirc (I don't use it very often).