Floating scope/DUT: How to explain to my boss that this is wrong? - Page 1
Forum section: electronics / projects

author: TimNJ
author_rank: Super Contributor
timestamp: June 29, 2017, 02:43:47 pm
content: Hi all,I started work as my first job as a design/project engineeer a few weeks ago at company which designs and manufacturers consumer/medical switchmode power supplies. I'm happy that I am working with my hands a lot and get to interact with the hardware.However, I'm not so happy/certain about their ideas on making safe measurements.First off, the Tek TBS scope that I use has its earth pin removed. I suppose this is called "floating the scope". The DUTs I test are powered via an isolation transformer. Everything I've ever read says "power your DUT with an isolation transformer but NOT your scope". Finally, sometimes to monitor two voltages, one on the primary side and one on the secondary side, we will short the primary and secondary grounds. I may be new, but this all sounds like a recipe for disaster.So right now, it seems like everything is floating, except for me! The DUT and the scope could be sitting at a high potential depending on where probes are connected. So when I make a mistake (and I have), I am a path to ground.Can someone please explain WHY these practices are unsafe? My boss is an old guy who acknowledged that "most people say not to do this, but I've never had a problem with it". It's going to be hard to sway him, but perhaps I could make him think about the problem if I bring it up.Thanks!

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 29, 2017, 02:49:39 pm
content: The ground clips on multi-channel scopes are connected to each other and to earth ground. You can remove the connection to earth ground, but you can't disconnect them from each other. That means that if you inadvertently connect the ground lead of one probe to something live, the ground leads of all of the other probes become live as well, including the shield on the BNC jacks on the scope itself. At that point it's about as dangerous as plugging a wire into the live socket on your wall outlet and then swinging it around your bench and clipping it onto things.

author: MosherIV
author_rank: Super Contributor
timestamp: June 29, 2017, 02:53:02 pm
content: Have you trawled through this (large) thread with a raging argument with the for/against why it is bad/unsafe or OK :https://www.eevblog.com/forum/testgear/floating-scopes/There are bound to be many good answers for you to use.Happy reading

author: alm
author_rank: Super Contributor
timestamp: June 29, 2017, 03:06:48 pm
content: Read what the manufacturer writes about defeating the ground connection in the manual. Or ask Tektronix tech support about it. They may even still have an application note that strongly recommends against that practice.If the boss is unwilling to believe the manufacturer and the common sense of having exposed metal at dangerous voltages, find a new boss. Differential probes or scopes with isolated channels are not that expensive.

author: borjam
author_rank: Unknown
timestamp: June 29, 2017, 03:25:23 pm
content: I don't think it's been mentioned, but your employer should have a look at current labor safety regulations.I guess it's not even legal to operate an oscilloscope without proper earthing when there is a good solution (differential probes). Remember that safety laws try to reduce risks to the minimum possible and any risk is considered unacceptable when there is a mitigation measure available.

author: CopperCone
author_rank: Super Contributor
timestamp: June 29, 2017, 04:06:52 pm
content: Oh come on, its not like I'm asking you to lick the thing!I would work on the stuff like its radioactive in the mean time. Slow down your work by 400% to make sure you don't make a mistake, until you find a new job.

author: alm
author_rank: Super Contributor
timestamp: June 29, 2017, 04:31:34 pm
content: Radiation dose depends on time, so if it were heavily radioactive, you would by trying to finish the work as quickly as safely possible.

author: WastelandTek
author_rank: Frequent Contributor
timestamp: June 29, 2017, 04:37:29 pm
content: If this asshat can't, or won't, spring for differential probes you need a new job.Direct violation of OSHA and state L&I

author: JPortici
author_rank: Super Contributor
timestamp: June 29, 2017, 05:07:12 pm
content: Quote from: alm on June 29, 2017, 03:06:48 pmtektronix will probably tell you not to do it... then suggest you get a tektronix TPS (that's it, as basica as a TDS can get but battery powered and with isolated channels)

author: tautech
author_rank: Super Contributor
timestamp: June 29, 2017, 06:39:07 pm
content: Quote from: TimNJ on June 29, 2017, 02:43:47 pmIt is.Your one saving grace is DUT's are powered through an isolation transformer........however you need check the mains earth is terminated and NOT fed through to the DUT.QuoteNot exactly IF the mains earth goes nowhere near the DUT, you are at lower risk albeit still at some risk if both legs of the mains supply are made contact with.QuoteAs above.QuoteOld buggers need learn a thing or two too.............you're never too old to learn.He needs reminding of the obvious:1. It will be on his conscience for the rest of his days if a fatal accident occurs under his watch.2. His neck will be in the noose too should the worst happen.How many K$ has he invested in test equipment so you can all do your job.......and he can't spring a few hundy $ for differential probes ?

author: Dubbie
author_rank: Unknown
timestamp: June 29, 2017, 06:56:57 pm
content: In NZ the company owner would be personally liable for any incident that happened due to this setup. Even if the tech floated their scope without the company owners knowledge, the owner could still risk jail and huge fines for not specifically having a policy and systems of checks to ensure it doesn't happen.

author: Vtile
author_rank: Super Contributor
timestamp: June 30, 2017, 12:25:13 am
content: If bothdevices are floating (strongly, not like the scope is done) and when they are connected then the whole system is still floating. Call me dump, but I still not see more risk in this setup( when surroundings are good and floating is done electrically and mechanically strong enough) than poking around in cluttered desk edge the live circuit in sweatty bare arms with differential probe.The white papers and modern safety regulations might disagree.That said. You need to make a technical and risks review between the old and the suggested procedure if there is no regulations against the current procedure (or the lab have special permit).

author: alm
author_rank: Super Contributor
timestamp: June 30, 2017, 12:49:23 am
content: No argument that there are straw men that are worse things than floating a scope, but I would argue the distinction between a floating DUT is that a DUT that contains dangerous voltage is generally expected to be dangerous. I would not stick my hand inside an SMPS to feel if the FET is hot. I would double check that the power is unplugged and measure for charged caps before touching it. A working scope is generally assumed to be safe to touch. You might plug in a USB stick to download yesterday's data without necessarily considering the DUT or taking a volt stick to test for dangerous voltages.Sure, if the scope is put in a plexiglass case with an interlock that cuts all power if the case is opened, then it could be made safe. Note the quote I posted in the other thread how even in 1982 it was not uncommon for companies to require safety ropes and people supervising while floated scopes were in use. So it is not exactly just modern safety regulations that consider it risky.Quote from: JPortici on June 29, 2017, 05:07:12 pmProbably, and I figured the opinion of a test equipment manufacturer might hold more sway with some bosses than the opinion of a junior employee. The old appeal to authority.

author: TimNJ
author_rank: Super Contributor
timestamp: July 03, 2017, 08:13:46 pm
content: Thank you everyone for your replies.I think for the mean time I will exercise extreme caution when probing live DUTs. I brought it up with one of the other engineers and he was convinced that there was nothing wrong with what we're doing. So, seems like a pretty up hill battle from here.For those interested, here's a nice document from Tektronix about floating measurements and safety:http://www.tek.com/document/technical-brief/floating-oscilloscope-measurements-and-operator-protection

author: tggzzz
author_rank: Super Contributor
timestamp: July 03, 2017, 09:40:55 pm
content: Quote from: TimNJ on July 03, 2017, 08:13:46 pmI have 5 steps outside my front door, with a railing. Normally I had my hand on the railing when going down; I never had to use it to stop falling. I have been up and down the steps several times a day for 30 years. That implies at least 10,000 times, probably 20,000 times, maybe more.Then, once, I was distracted by thinking about two different things as well as going to shut the car door, and forgot the steps were there until one foot was just about to miss the step - and my hand was nowhere near the railing. I instinctively elected to jump, landed fine where I indended, but since I'm no longer rubbery a tendon in my knee snapped. Into hospital, operation, and after 3 months I could start learning to walk again.Moral: past performance is not a guarantee of future performanceDoubly so when you are relying on other people not to forget something while they are distractedThe "it hasn't hurt me yet so it won't hurt me" attitude is often contagious to other behaviours. At some point you are going to want to think whether you want to continue to work for/with this mob.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 03, 2017, 09:58:51 pm
content: You only need one reason: it's a safety hazard unambiguously identified as such by the scope manufacturer and by default ruled illegal by OSHA. Full stop.Your employer cannot force you to undertake unsafe work practices, and if defeating a manufacturer-supplied safety earth ground isn't unsafe, then what is?Employers rarely give a damn about anyone's personal well being. They do care about money. They care about lawsuits and bad publicity. Phrase your concern in regards to the costs/hassles if someone becomes injured. It's a technique that virtually always works.Welcome to the working world. This will be the first of many discussions (unfortunately) that you will likely need to have with employers regarding safe work practices. Over a couple of decades, I am still flabbergasted by the conversations that must be had with employers about this stuff.Document everything IN WRITING. Mail a copy to yourself to a Gmail or similar account that you maintain solely for the purpose of maintaining these records. If things go south and your employer retaliates, you may be protected as a whistleblower.===============The solution to needing a floating scope is relatively simple: buy proper differential probe or a battery-powered oscilloscope.

author: cdev
author_rank: Super Contributor
timestamp: July 03, 2017, 10:29:26 pm
content: If I were you I would bring the fact that its unsafe up one more time and if you're brushed off again, unless for some other reason you really like this job, start looking for another one. Life is too short to waste years working for people who are willing to risk yours!Chances are you'll get another better job easier when you already have one, too. Seriously, count yourself lucky that you figured this out early on and not after you had already invested a lot of energy into this employer.

author: Fungus
author_rank: Super Contributor
timestamp: July 03, 2017, 11:25:00 pm
content: Quote from: alm on June 30, 2017, 12:49:23 amYep. I've got some USB sticks with metal cases.I'm not usually expecting to be electrocuted by plugging in a USB stick but a floating 'scope makes it possible.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2017, 12:14:35 am
content: Quote from: LabSpokane on July 03, 2017, 09:58:51 pmHow does a battery-powered oscilloscope solve the problem?

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 12:35:49 am
content: Quote from: Fungus on July 04, 2017, 12:14:35 amThere is no earth return on a battery-powered scope when unplugged from its charger.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 12:42:54 am
content: Quote from: cdev on July 03, 2017, 10:29:26 pmIt's not worth it at all. Never forget the power of precedent. Once you accept this poor practice, it becomes the rationalization for more.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 01:08:24 am
content: Quote from: blueskull on July 04, 2017, 01:00:53 amI'll bet that $8K probe is about $8MM dollars cheaper than the settlement of the wrongful death lawsuit. It's not a lot of money when put into proper perspective.As far as the "genuine" HV diff probe, those are largely made by the same manufacturer that Dave's, Keysight, and everybody else's is. My 70Mhz from Dave was $320 IIRC. A 100MHz probe from Probemaster is under a grand:http://probemaster.com/differential-probes/Even if it was 10X those costs, a manufacturer of high-zoot medical power supplies can afford it. There is little margin pressure in the medical device industry.

author: Electro Detective
author_rank: Super Contributor
timestamp: July 04, 2017, 02:15:34 am
content: If you want to keep your job, I'd say be extra careful, the next employer may be worsemake sure YOU are isolated in case things go zapBANG!and wear protective eye glasses always when doing this stuff !MOST'if it ain't broke..'bosses won't spend one cent, been there a few timessome smartass(undeservedly too rich aka 'Daddy's money' syndrome)serial cheapskates or their clipboard queen stupidvisor will poke you with"perhaps you're not busy enough if you've got time to think about this.."BS when you alert them to hazards and suggest a quick cheap compliant fix.FWiW none of them are in business anymore, I don't know why, and I don't gas,hoping they went belly up with huge debt,or maybe an employee or premises got fried and company sued out of existence.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2017, 02:21:22 am
content: Quote from: LabSpokane on July 04, 2017, 12:35:49 amAll the external metal on a battery 'scope is just as live as the external metal on a floating 'scope after you attach your ground clip to the DUT. The floating 'scope is isolated by the transformer in its power supply.

author: alm
author_rank: Super Contributor
timestamp: July 04, 2017, 02:29:29 am
content: A well designed battery-powered scope will generally not have any exposed metal, because they have no reliable way of connecting it to a safe potential (this even applies to the old CRT-based battery powered scopes like the Tektronix 200 series). They use insulated probe connectors, isolated communication interfaces and a well insulated plastic case, similar to DMMs. They should also use probes with insulated ground leads (e.g. MC IsoProbe). The exception to this is some bench scopes with an optional battery, but their manual will usually tell you to run a separate ground wire when used around dangerous voltages.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2017, 02:34:56 am
content: Quote from: blueskull on July 04, 2017, 01:00:53 amThe problem is that your lab is setupdifferentto the norm. People are fallible. They might not know the 'scope is floating, they might forget to float the DUT, etc.The key to safety is not to have any surprises or unusual setups, no matter how 'safe' they may be in theory.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2017, 02:38:25 am
content: Quote from: alm on July 04, 2017, 02:29:29 amhttps://en.wikipedia.org/wiki/No_true_Scotsman

author: Muxr
author_rank: Super Contributor
timestamp: July 04, 2017, 02:40:24 am
content: I don't know if they let you bring your own equipment. But I would probably get a handheld scope, and bring that to work instead. If the boss can't be reasoned with to buy the appropriate equipment that is. And look for another job.

author: timb
author_rank: Super Contributor
timestamp: July 04, 2017, 02:54:46 am
content: Quote from: Fungus on July 04, 2017, 02:21:22 amAll battery powered scopes *designed for floating measurements* will have all the channels isolated from each other (so each one has its own ADC which uses an isolated communications interface to talk to the main processor; this way the GNDs between BNC connectors are *not* shared).They generally use plastic cases and have no exposed metal surfaces that are grounded.Whereas a normal scope has a common ground between all BNC connectors and other exposed metal parts (like the USB connector, the GND connector for the probe calibration signal and so on).Also, the SMPS used in a bench scope doesn't provide true isolation. Keep in mind you have Y-caps in there, which cause leakage current to flow. At any rate the power supply of the scope has little to do with the problem we're discussing. Here it is in a nutshell for you:Say you defeat the safety GND connection of your scope (there's no continuity between any of the BNC shells and the third pin of your wall outlet). So you clip the GND lead from your probe onto a part of your DUT that's at 250VAC. Now, what happens if you touch one of the other exposed, metal BNC connectors of your scope? You become a path for that 250VAC to ground!Same scenario, but this time you have the DUT hooked up through an isolation transformer. Touching the metal BNC of the scope shouldn't shock you, right? Assuming you're using a true isolation transformer and not a medical isolation transformer (which has N and G bonded on the isolation side) you *should* be alright. However, there are a lot of things that can go wrong in this scenario. Here's one: What if I hook a non-isolated function generator up to the DUT? Whoops, I've just defeated the isolation and now all the exposed metal surfaces of my scope are live!Why worry about all these variables when you could simply get a differential probe (or a true floating, battery powered scope) and be done with it?

author: AG6QR
author_rank: Frequent Contributor
timestamp: July 04, 2017, 03:07:01 am
content: Quote from: blueskull on July 04, 2017, 01:00:53 amBut the first post explains that the DUT is floated via an isolation transformer. That defeats any GFCI, rendering it useless. One might argue that it also eliminates the need for a GFCI, and there's some truth to that. But I'd offer the rebuttal that, with a GFCI (and no isolation transformer), the first time current finds a path to ground, the GFCI shuts everything off, and that's probably safer than leaving the circuit live.As for a defibrillator, well, yes, there ought to be one on premises, but your goal should be to NEVER require its use. If you have a serious enough shock to require defibrillation, your chances of that shock being fatal or disabling, even with quick use of an AED, are far higher than I'd ever be comfortable with.

author: alm
author_rank: Super Contributor
timestamp: July 04, 2017, 03:14:54 am
content: Quote from: Fungus on July 04, 2017, 02:38:25 amSo your claim is that floating a standard bench scope is safe because there are battery powered scopes out there that are just as unsafe? Good luck with that.

author: AG6QR
author_rank: Frequent Contributor
timestamp: July 04, 2017, 03:15:58 am
content: Quote from: blueskull on July 04, 2017, 03:10:15 amThat wasn't the point you made when you said that floating the DUT "sounds not a bad practice" to you.When you float the DUT, you lose the GFCI protection. If you want GFCI protection, you can't float the DUT. You don't get to have it both ways.And that's my point.

author: alm
author_rank: Super Contributor
timestamp: July 04, 2017, 03:23:51 am
content: But one hand on the scope and one hand on the isolated circuit should be fine, right?

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2017, 03:30:59 am
content: Quote from: alm on July 04, 2017, 03:14:54 amI never said it was safe to float a 'scope, quite the opposite.I'm saying not all "battery powered 'scopes" are safe.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2017, 03:34:19 am
content: Quote from: blueskull on July 04, 2017, 03:20:23 amIf it's all floating then the GFCI/RCD won't trip. You can happily grab both wires of the isolation transformer and nothing will happen.

author: Lightages
author_rank: Unknown
timestamp: July 04, 2017, 03:35:38 am
content: I'll bet the company of the OP is ISO9000 certified in some way. I'll also bet that their certification is dependent on following laws and rules of safety. I wonder what would happen if an inspector was anonymously called to do an inspection.....

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 03:55:36 am
content: Quote from: Fungus on July 04, 2017, 02:21:22 amThe inputs are insulated and isolated for this very reason. These are typically used in an industrial environment with the benefit that it's tough to close a ground loop with one, but if one really needs 4 channels of 100+MHz with isolation between inputs as well as ground for another purpose .... well here you go for a cool $5-6K.That's less than 10 hours of Patton Boggs defending your hopeless position in Federal court. A bargain at twice the price.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 04:05:28 am
content: Quote from: Fungus on July 04, 2017, 03:34:19 amIf you "happily grab" both leads of the isolation transformer, you won't be so happy in about 1/60th of a second.

author: cdev
author_rank: Super Contributor
timestamp: July 04, 2017, 04:18:37 am
content: Micsig makes a scope with floating inputs.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 05:04:11 am
content: Quote from: blueskull on July 04, 2017, 02:30:58 amAmerican law and OSHA regulation does not work that way. Your employer cannot lawfully force you to engage in patently unsafe work - particularly situations that are so easily resolved. They cannot force you to work under a suspended load. They cannot force you to perform high work without fall protection. They cannot force you to fly an airplane that cannot pass safety inspection. They cannot force you to work on live power lines without a properly isolated bucket truck, hot sticks, etc.Some work hazards are inherent in the work and cannot be readily mitigated, but that is not what we are discussing here.Your employer is not permitted to place a value upon your life as you describe.And your extrapolation is what disreputable employers throw in your face to make inexcusable situations seem reasonable - even though the solution is a few dollars. Everyone in this company does not have a safety issue over power supply testing with an oscilloscope. One or two do. Fix it properly and be done with it. If the work environment at one's employer is so unsafe that it will truly bankrupt the company to rectify it all, perhaps closure of that workplace is what's best for all concerned.Let me say this to you as an old man to young men and women who are just starting their careers. Do not settle for being treated by your employer as though your life and safety don't matter. The amounts of money to conduct safe work are typically not the vast sums that disreputable employers whine and cry about. They are usually pittances in the grand scheme of things. They are business costs that should rightfully be factored into the price of the product or service.When you don't stand up for safe work practices, you're not just endangering yourself. You're putting in danger everyone's safety and job security. Accidents come with huge costs and impacts and its virtually always cheaper to not have one. Now is the time to set the tone with your employer that you're a great employee, but that you expectreasonablemeasures to ensure a safe workplace. It's a two-way street. Don't let these cheap, old codgers browbeat you into bad work practices. I guarantee that once you start down that road, it's tough to go back. That road is a gut wrenching road, filled with worry, ulcers, and sleepless nights.Have your facts in order and stand your ground. It's better in the end.

author: mrpackethead
author_rank: Super Contributor
timestamp: July 04, 2017, 05:09:40 am
content: Quote from: blueskull on July 04, 2017, 02:30:58 amNot all boss'es are like this. Some take staff saftey and wellbeing very seriously.

author: tautech
author_rank: Super Contributor
timestamp: July 04, 2017, 05:17:56 am
content: Quote from: cdev on July 04, 2017, 04:18:37 amAnd Tek and Siglent and........Your point is ?The real issue is the price......I mean the componentry for each isolated channel is only a few $ but manufacturers expect that they can extract real $ from buyers like the cost for individual differential probes/channel.Handhelds are just the current market's solution for this age old problem and as has been pointed out not all HH's offer fully safe solutions.

author: Phoenix
author_rank: Frequent Contributor
timestamp: July 04, 2017, 05:48:39 am
content: Quote from: TimNJ on June 29, 2017, 02:43:47 pmYou can have problems with diff-amps with poor offset performance, or if you want to look at a a small signal level digital/analogue signal node on the floating side.Get a Tektronix TPS2024! My favourite oscilloscope for SMPS design (pretty bad otherwise, but not many well featured isolated scopes to pick from). 200MHz, 4 isolated channels, with very good common mode separation - my experience is that you can have once ch sitting on the switching node bouncing +-400V and another on a signal node around 0V without problem.Range of high voltage non-differential probes e.g.http://www.tek.com/high-voltage-probe-single-endedP5122 is one I like -http://uk.rs-online.com/web/p/oscilloscope-probes/7121141/Note the different degrees of protection on being able to touch the BNC connector which will probably still be hazardous to touch!Does the company you work for often take on "new" staff? Or are they just used to their way?

author: LabSpokane
author_rank: Super Contributor
timestamp: July 04, 2017, 05:54:35 am
content: Tek has an app note for this situation.Pertinent excerpt:

author: mrpackethead
author_rank: Super Contributor
timestamp: July 04, 2017, 05:56:05 am
content: Quote from: blueskull on July 04, 2017, 05:24:40 amBut likely you will still be alive.

author: JPortici
author_rank: Super Contributor
timestamp: July 04, 2017, 07:21:37 pm
content: Quote from: Phoenix on July 04, 2017, 05:48:39 amtrue. have one to look at injectors and other stuffdamn tek should make us the courtesy to release a "C" version with more than 2.5kpts of memoryseriosuly, what changed between first and "B" revision? (we have a first revision from 2012 or 2013)

author: cdev
author_rank: Super Contributor
timestamp: July 04, 2017, 07:47:04 pm
content: Hey, his experience was real. Only idiots don't learn life lessons from things like that.We all would really hate to see you vanish from these forums, and find out through some fluke that you had been electrocuted.Also we want you to have a long and illustrious career, not have it be cut short by a dumb mistake. In fact, we want you to become an advocate for high voltage safety someday, when you're a bit older, like we are.When we're young, we often don't realize how fragile and short life is.Quote from: blueskull onYesterdayat 23:24:40>Quote from: LabSpokane onYesterdayat 23:04:11I work at an overly safe and annoying work place that everything must be approved and proved to be absolutely safe. A simple test with less than a few joules of capacitively stored energy and 1mA source limitation demands a formal approval and we do that all the time.The overly safe concern makes doing effective works very hard and tedious. I hope those making safety rules have more common sense.I was recently fucked by a new requirement for a device I am building. The new rule says even with double failure and ground bar fault (which is the least likely to fail part for obvious reason), no one shall be harmed. This, combined with 8kV operating voltage (which means practically no isolation xfmr is available) makes me to redesign everything.Now, I have to finish this very soon as I depend on this to earn my PhD degree, and they suddenly told me to redesign everything just because our safety liaison, in his other job, recently came across a few electrocuted guys and he's so scared of another casualty.Effectively I have to get rid of ALL 120V mains and ALL copper connections from the system except for 1kV input and replace everything with fiber and add hardware, no MCU, kill switches, plus I now have to build a plexiglass house to contain all possible shock hazard and explosion hazard. Great, another 2 months delay in my graduation.

author: Phoenix
author_rank: Frequent Contributor
timestamp: July 05, 2017, 02:47:14 am
content: Quote from: JPortici on July 04, 2017, 07:21:37 pmExactly!

author: alm
author_rank: Super Contributor
timestamp: July 05, 2017, 03:16:32 am
content: Are the B/C suffixes ever a significant upgrade with Tek? I would expect a TPS2000C scope to have the exact same acquisition system but with USB 3.0 ports, maybe WiFi and some minor software upgrades. To get more acquisition memory, you would have to wait for some hypothetical TPS4000.

author: Electro Detective
author_rank: Super Contributor
timestamp: July 06, 2017, 12:46:54 am
content: Quote from: LabSpokane on July 04, 2017, 04:05:28 amGood show guysI was holding back to see just how long that was going to pass here, before pointing out the obvious safety concernand bore everyone with how a GFCI/RCD/MCOB works(with or without lubing the contacts very sparingly with xx40)