These were like 20 kV rated back in 1974 and 1983 ... when I've used them.
could do 40 kV 100 mS pulse according to datasheet.

 

The Oft Repeated Cautions are for beginners who don't understand why they need an isolation transformer, not seasoned pros...

Thanks for that! -- Indeed! @Aleph(0) knows what she's doing! That said, we're always open to discussion of and/or input regarding safety concerns!

To be clear - Inasmuch as @Aleph(0) was merely monitoring her (mains) distribution transformer secondary, she would have had no requirement of 'HV' probe{s}/dividers -- While I ignore the identity/details of the specific instrument/procedures employed, I can say that several (if not all) of her instruments of that 'caste' (i.e. MDOs) are (optionally) operable from self-contained (i.e. on-board battery powered) PSUs and exhibit guaranteed input-channel to case/control insulation of > 750V DC/Line freq AC...

These were like 20 kV rated back in 1974 and 1983 ... when I've used them.
could do 40 kV 100 mS pulse according to datasheet.

FWIW - We generally prefer high power dividers (of the general form pictured below) to 'probes' as applied to DC/Low frequency EHT measurement/analysis (to Ca. 500kV) -- It has been my sad experience that probes, no matter how (ostensibly) 'high quality' are treacherous at EHT -- and there is little more disruptive of a project than awaiting shipment of replacement test gear

Many thanks for your interest, information and kind words!
HP

 

While I ignore the identity/details of the specific instrument/procedures employed, I can say that several (if not all) of her instruments of that 'caste' (i.e. MDOs) are (optionally) operable from self-contained (i.e. on-board battery powered) PSUs and exhibit guaranteed input-channel to case/control insulation of > 750V DC/Line freq AC...

Are you certain about what you say regarding her instruments? As far as I know, only one manufacturer makes mixed domain oscilloscopes, namely Tektronix (the MDO3000 and MDO4000 series). According to the user manuals, none of the instruments can be battery operated, nor do they have isolation between the input channels and the various networking protocols.

Could it be that Aleph used MDO as an abbreviation for something else?

 

Could it be that Aleph used MDO as an abbreviation for something else?

I very much doubt it!
But then you may ask her yourself this weekend

As far as I know, only one manufacturer makes mixed domain oscilloscopes, namely Tektronix (the MDO3000 and MDO4000 series)

Granting that 'MDO' may indeed be a Tektronix 'trademark' -- To be certain, said 'designation' enjoys longtime adoption as a 'form taxonomy'

According to the user manuals, none of the instruments can be battery operated

But then I seem to recall availability of said option at the time I ordered @Jazz2C's replacement MDO3104...

nor do they have isolation between the input channels and the various networking protocols.

The 'isolation' is between the input channels and the external surfaces of the instrument, ports, controls, etc.. (this I know from first hand experience Re: the MDO4104C )

@The Electrician if your belabourment of this issue owes to said instruments' 'bargain basement' pricing - I hear you (I was initially skeptical myself)! -- That said, they really do meet their specs and with the added 'bonus' of 'painless replaceability' when 'stuff' happens... Making them, IMO, ideal general purpose 'shop' (as opposed to lab) instrumentation...

Best regards
HP

 

So HP told me there's big fuss on here cuz I'm talking abt measuring line offset with scope

Granting that 'MDO' may indeed be a Tektronix 'trademark' -- To be certain, said 'designation' enjoys longtime adoption as a 'form taxonomy'

HP that's right! Avcom was first on market with TDO-FDO combos but they didn't call them MDO so ur prolly right abt Tek trademark!

none of the instruments can be battery operated

Electrician WRONG! _Portable_ PSU isn't standard but it's vendor option that buyer is totally crazy not to order!

nor do they have isolation between the input channels and the various networking protocols.

Electrician they're insulated just as HP says except it's 750v DC and 1500v Pk-Pk total excursion (which is basically redundant if you think on it).

But then I seem to recall availability of said option at the time I ordered @Jazz2C's replacement MDO3104

HP Don't worry! You recall right!

if your belabourment of this issue owes to said instruments' 'bargain basement' pricing - I hear you (I was initially skeptical myself)! -- That said, they really do meet their specs

HP I agree! Even though they're basically the _Harbor Freight_ end of Tek line, they function as speced which like you say is perfect for just casual general purpose field use cuz of super low cost! So being fair to Tek I've never seen a failure that wasn't fault of user!

So @The Electrician If ur saying I'm negligent idiot all I can say is ur wrong! I don't know why you ignore repeated requests for constructive input then sporadically come along just to _snipe_ at nothing! If it's an aftermath of the _RK drama_ then I say you need to get over it cuz it's a long time ago and anyhow you came out of that better than anyone else!

So just in case you're really worried abt safety you can relax cuz I'm saying that if I didn't know what equipment someone was using I'd just suggest using RC filter and dmm for reading offset on line (which I say is accurate enough for most purposes)!

So as far as I'm concerned this topic of scope safety is now talked out! Time to move on!

PS -- Offset is caused by equipment of neighbor on same secondary, so I'm having hydro install dedicated _pole pig_ for my property! So it's nice to have problem just solved!

 

HP Don't worry! You recall right!

Happy days (daze?) -- No Namenda for HP anytime soon! (But then I do have another @#&$%ing B-Day coming up)

though they're basically the _Harbor Freight_ end of Tek line

And I would say said instruments represent Tektronix quality at Harbour Freight pricing

I've never seen a failure that wasn't fault of user!

DITTO! -- Ya getting this @Jazz2C ?

they function as speced which like you say is perfect for just casual general purpose field use cuz of super low cost!

There is indeed something to be said for test equipment one is not tempted to pamper!

So just in case you're really worried abt safety you can relax cuz I'm saying that if I didn't know what equipment someone was using I'd just suggest using RC filter and dmm for reading offset on line (which I say is accurate enough for most purposes)!

--Emphasis Added--

Said technique would certainly reveal an offset sufficient to produce audible 'symptoms' in a transformer!

So as far as I'm concerned this topic of scope safety is now talked out! Time to move on!

While safety is always on-topic I tend to agree with your assertion to the effect that this is indeed 'well explored territory'...

PS -- Offset is caused by equipment of neighbor on same secondary, so I'm having hydro install dedicated _pole pig_ for my property! So it's nice to have problem just solved

!

Sounds like an excellent opportunity to 'upgrade' to 3-Phase service?

I'm certain we're all dyin' to know the nature of the 'offending' load? -- Would I be far off 'the mark' was I to guess some manner of 'transformerless' battery charger?

Very best regards
HP

 

Are we talking about an off center output from a 240 volt, center tapped pole pig?
My experience with field failures has always been about resistance in the "common" wiring from the center tap to the load.

 

I'm certain we're all dyin' to know the nature of the 'offending' load? -- Would I be far off 'the mark' was I to guess some manner of 'transformerless' battery charger?

HP All I know is it has something to do with his _solar power station_ which I say is more work than it's worth even if it was on equator but at latitude of like 52° it's just totally lame!

My experience with field failures has always been about resistance in the "common" wiring from the center tap to the load.

#12 afaik transformer is ok! It's just penny wise dollar stupid neighbor's pet project causing offset on secondary cuz when he opens connections to line, offset disappears

Sounds like an excellent opportunity to 'upgrade' to 3-Phase service?

HP there's just single phase line for primary so when I asked abt that last year hydro gave me option of running a 3-phase spur from substation 45 km away or installing big rotary converter (Cuz I don't want electronic phase converter cuz they totally suck for reliability!) So anyhow I can ask hydro which option can be done soonest cuz ur right about need for rugged 3-phase service!

HP FWIW I don't understand why that can't just be done with special transformer like feeding single phase across one leg of wye network and then just taking 3-phase off ends of legs as usual? Sry cuz of being basically clueless abt magnetic components

 

HP FWIW I don't understand why that can't just be done with special transformer

I dunno... I too have often thought (albeit it not 'deeply') that construction of a stationary transformer featuring three windings/taps separated by electrical angles of 120° should be feasible... That said, inasmuch as I've not heard tell of such apparatus, I must assume same to be inadmissibly inefficient or otherwise impractical...

like feeding single phase across one leg of wye network and then just taking 3-phase off ends of legs as usual?

Re: standard distribution equipment: I cannot envision development of 120° phase-shifts from a single-phase line via stationary (i.e. non-rotary) transformation devices? -- That said, I'm maintaining an open mind on the subject should you care to elucidate?

I asked abt that last year hydro gave me option of running a 3-phase spur from substation 45 km away or installing big rotary converter

So anyhow I can ask hydro which option can be done soonest

The fact that they offered the 'spur' option tells me that an existing corridor/'right of way' accommodative of same is currently available (likely a matter of merely 're-wiring' existing poles) Which being clearly your best option for all around reliability! -- That said, a large 'rotary converter' is a good option also! Moreover, I can all but guarantee the poco can have done with it in markedly shorter order than putting up/upgrading 30 miles of line!

I don't want electronic phase converter cuz they totally suck for reliability!

Well you know - you're preaching to the choir in that regard!

Sry cuz of being basically clueless abt magnetic components

If it's any consolation - there seems to be plenty of that around!

Very best regards
HP

 

I cannot envision development of 120° phase-shifts from a single-phase line via stationary (i.e. non-rotary) transformation devices?

HP so ur saying that like delta-wye xfmr is just 3 sets of windings on 3 totally separate closed magnetic circuits? Cuz if so I say that's really just three single phase xfmrs with primaries wired in delta configuration and secondaries wired for wye configuration and vice versa!

I too have often thought (albeit it not 'deeply') that construction of a stationary transformer featuring three windings/taps separated by electrical angles of 120° should be feasible

HP I agree it's theoretically possible but it's hard to think on when number of phases is odd w/o using rotating secondary to generate missing excitation phases! So just focusing on 1∅ to 3∅ conversion I say it's good thought experiment to think on how arrangement of stationary windings in interacting magnetic circuits could split single input signal into three identical angularly equidistant signals! So I have feeling I'm overlooking something totally simple just cuz of being intimidated abt magnetic devices!

The fact that they offered the 'spur' option tells me that an existing corridor/'right of way' accommodative of same is currently available (likely a matter of merely 're-wiring' existing poles)

HP that's prolly right but I say hydro will still take their own sweet time getting job done

That said, a large 'rotary converter' is a good option also!

HP it's not as electrically solid as proper 3∅ service and even though there are no brushes it's still moving parts running all the time! So that's huge reliability fail right there!

So from what they said 45 km spur would be 69kv line with stepdown xfmrs here on site which means rock solid 3∅ So I agree that's best option if they can get to it sometime this century Being totally serious I'm willing to wait as long as 2 yrs for guaranteed completion date but I won't know what timeframes are available b4 I talk to them hopefully next week. So for now it's just having dedicated pole xfmr installed which they say will be done Tuesday

If it's any consolation - there seems to be plenty of that around!

Ok super cop-out alert! I say reason most ppl are weak on magnetics is fault of education system and scientific, engineering and hobby publishing community cuz electronics is treated like the science it is but magnetics is mostly treated as just idgit vocational tradesman BS! One exception used to be RF xfmrs (like baluns and TLTs and like that) but so many crybabies were complaining it's too complicated for their lazy feeble minds to grasp that ARRL basically dumbed down their handbook to pacify the losers! That's why I will NEVER renew my ARRL membership cuz any organization that's ok with extra class license going to ppl who only have math through algabra-trig is total sham when they spout their high tone _code_ about _advancement of the art_! All they want advanced is their revenues and that means appealing to vanity of numpties!

OK! I totally feel better now!

 

I've said before, I would love to spend a week with you two, but I'd probably find you are as wrinkly as I am

No wrinkles here - yet - tho' I've no fear time will 'take care' of that -- Said dreary observation being yet another in the veritable litany of admonitions as regards the inadvisability of 'clock watching' , as it were

and Aleph is insufferable.

As regards Aleph's 'off-list' 'insufferability' - In her own words:

ppl say I come across as just _overcompensating young professional_ when out of Aleph character So I prefer dumb but likeable web persona!

what you do that makes an MDO 'scope seem cheap at several thousand dollars.

By 'cheap' I meant merely that the price is very low -- Absolutely no aspersions upon quality intended!
IOW: At Ca $20k apiece (fully equipped) it's as a 'new take' on that antediluvian Conco (SP?) footwear ad - To wit: "Tektronix doesn't sell cheap scopes, Tektronix sells good scopes cheap!"

FWIW my first choice in 'laboratory grade' test equipment is Hewlett Packard AKA Agilent AKA Keysight -- IMO serious research deserves exemplary equipment!

I've seen both of you leap to correct conclusions that I can't figure out after you showed me how you did it

---Emphasis Added---
Don't let that bother you! -- Among the many 'lessons' learned in the course of my participation here (and throughout my attempts to assist @Jazz2C ) is the sad fact that I'm no instructor! -- That said, I promise to keep trying!

I've caught you in some penny wise and pound foolish adventures.

But then, where applicable, 'DIY' projects have educational value and, not uncommonly, yield better end results than obtainable via (equivalent) commercially available products (if only by dint of 'tailorability'/serviceability)

I'd love to see how you think that creates such a contradiction.

As an 'off the cuff', purely hypothetical example: Investment of $2M in a private 'wind farm' with the aim of saving $25k/Yr in utility fees comes to mind

Very best regards
HP

 

As regards Aleph's 'off-list' 'insufferability' - In her own words:

"ppl say I come across as just _overcompensating young professional_ when out of Aleph character So I prefer dumb but likeable web persona!"
Overcompensating wouldn't be terribly off-putting. I have been an overcompensating young professional. It's annoying, but it's understandable. One merely needs to put the actor at ease and that's why I said, "a week". Nobody with good sense will support a false persona for more than a couple of days, and I already know both of you have good sense.
Actually, I booted a woman for playing the stupid bimbo. Refusing to, "get real" apparently bothers me more than the human nature of trying to present yourself well when you're not all that familiar with how to do it.
My advice to @Aleph(0) is, "Be yourself." The day I quit overcompensating is the last day anybody questioned my CV.
A customer said, "You look like you're too young to fix TVs." I replied, "You look like you're about 80 and you can't fix 'em, so what does age have to do with it?" Then I turned on my heel and left her to wait for another repairman. I thought I was going to get fired for that outburst, but nobody ever confronted me about it.
I've been waiting 45 years for the opportunity to tell a customer, "Hide and watch." but it never came.
Apparently "getting real" put some credits in my Karma account and I never had to do that again.
Besides, look at how I present myself here. I am the same person in the real world, including the part about addressing the audience at their level. You would probably have to try to address me at my level, but if you think this isn't the real me, your "numpty" persona has a basis in fact.

By 'cheap' I meant merely that the price is very low

Completely unnecessary explanation. Sorry about using a word with different interpretations available. My bad.
How bad was it? So bad that you completely escaped explaining how you can spend a year of my disposable income and call it a bargain.
(You must be getting paid well for your, "research"!)

'DIY' projects have educational value and,

I'm talking about discarding enough stainless steel to make a year's pay for me and being glad he didn't charge you to haul it away.
I was thinking, "OMG! I would pay you for a chance at that job, and you just gave it away!"

Edit: I don't expect to ever see either of you in person. I'm just having a nice, low risk conversation.

 

A customer said, "You look like you're too young to fix TVs." I replied, "You look like you're about 80 and you can't fix 'em, so what does age have to do with it?"

FWIW, that made my evening! ROFL

 

How bad was it? So bad that you completely escaped explaining how you can spend a year of my disposable income and call it a bargain.
(You must be getting paid well for your, "research"!)

@#12 what can I say? At a price of Ca. $20k, said instrument is an excellent (IMO almost too good to be true) value! -- But then you needn't take my word for it - have a gander at prices of other instruments offering similar functionality, service contract/warranty , etc...

Putting this into perspective; we're talking a piece of versatile, high-quality, precision electronic test equipment offered for ≈ 50% the price of an 'entry level' automobile! - If that's not a bargain then I'm afraid I ignore the definition of the term

You must be getting paid well for your, "research"!

My research projects -while marginally compensated (at best)- represent bona fide 'labour of love' Which, IMNSHO, being precisely as it should be! Business and creativity are the worst possible 'mix'!

I'm talking about discarding enough stainless steel to make a year's pay for me and being glad he didn't charge you to haul it away.

@#12 Why is it so difficult to understand that I wanted rid of that steel ASAP if not sooner! (a service for which I fully expected to pay upwards of $100k) -- Hence my surprise and delight at their eagerness to begin work the very afternoon I called - free of charge! -- When one experiences an embarrassing setback (as did I via discovery that I'd purchased the 'wrong grade' of 'stainless') one wishes to 'erase the error' and 'get back on track' immediately!-- Perhaps you'd feel likewise had you 24 tons of 'I'm stupid' staring you in the face?

That said, it was both insensitive and ignorant of me to ascribe the salvage operators' alacrity in said matter to evaluation of money over time!

and you just gave it away!"

Not quite! They put in a great deal of hard, hazardous work cutting, loading and hauling -- The value of said labour, IMO far exceeding scrap value!

A customer said, "You look like you're too young to fix TVs." I replied, "You look like you're about 80 and you can't fix 'em, so what does age have to do with it?"

Such disrespect for your elders?! Tisk, tisk, tisk

Very best regards
HP

 

Apparently "getting real" put some credits in my Karma account and I never had to do that again.

A bit of thought brings this idea: "Getting real" changed how I present myself and people can sense my perspicuity.
After I jumped that psychological obstacle, my demeanor has been without timidity. I walk in like I own the place and proceed to find and fix the problem without regard for personalities. Of course, this has is faults, too. My disregard for personal or emotional investment leaves the customers bereft of warm fuzzies. It has been my experience that nobody can please more than 97% of all customers and I know from whence my 3% arises.

One of my early strategies was, "Look at all the female customers as if you were restraining yourself from asking them for a date." It works, but I quickly developed a global case of "Don't Care" and lost that competitive edge.

As for the old lady, I was 20 years old at that time, and I have such a baby face that the last time I was forced to show I.D. to get into a bar, I was 42. Looking at me from her age, I must have appeared prepubescent. I had that experience 3 years ago when I looked up at the ambulance attendants and thought, "OMG! They sent children."

ps, they were entirely effective and I have no complaints, only regret that I left 5 finger size bruises on each of them when I screamed and grabbed their arms.

Why is it so difficult to understand that I wanted rid of that steel ASAP if not sooner!

That isn't the question. The question is, "How could you discard such a precious metal for free?" To people like me, it is like requesting I remove the offensive chunks of gold discourteously littering your lawn. For Dog's sake! There are people collecting empty aluminum cans to survive! Gawd, I wish I had customers like you!!!
But then, you successfully located your point of ignorance.

Disrespect for your elders?! Tisk, tisk, tisk

No, the last house call at the end of a truly miserable day caused a complete lack of empathy.
I already felt like, "kicking the cat" and she merely jumped up and down, waving her arms, and declaring, "Meow!"

I might pretend I regret my behavior, but it was a developmental goal I had to cross to continue my maturation process. That's why I recommended that lesson for Aleph.

 

"How could you discard such a precious metal for free?"

And therein lies the 'crux' of our misunderstanding! They 'payed' plenty for the metal with their hard work and adherence to my stringent 'time table'! --- Come to that, it might be said that I was rid of the metal for free!

For Dog's sake! There are people collecting empty aluminum cans to survive!

Ya know... that reminds me of my parents' demands that I 'eat my Brussels sprouts ' on the basis that people were starving 'overseas' -- By the same token I cannot, by any stretch of logic, see where charging for that scrap would have helped the the 'impecunious'? --- Please be advised that I remitted the entirety of my tax burden associated with said transaction...

Best regards
HP

 

I admit that the, "starving people" argument is invalid, but that isn't my point. I collect aluminum cans, crush them, and sell them for $10 per garbage bag full. I regret that you got your nuisance removed for free when you could have received ten or twenty thousand dollars for it. I regret it wasn't me, working so diligently to earn ten or twelve times my usual rate of pay. I am jealous!

Please be advised that I remitted the entirety of my tax burden associated with said transaction...

That stumps me. How is there a tax burden for no income at all? Possibly a tax write-off for your loss, but I can't figure out how you owed more taxes.

 

That stumps me. How is there a tax burden for no income at all? Possibly a tax write-off for your loss, but I can't figure out how you owed more taxes.

Under Mn state law sales tax extends to 'barter transactions' hence my stipulation that the value of services rendered me (via removal of the steel) equaled the scrap value of same (which being the maximum tenderable stipulation of 'taxable worth' in said case)... Hence my liability (as a seller) ≈ $1500 following each jurisdiction's 'take'...

@#12 I was aware that Florida does not impose personal income tax -- Am I to understand that you are 'sales tax free' as well? -- Seems I'm the one who should be envious! --But then I suppose a it's little enough compensation for living in a rather large sauna!

Very best regards
HP

 

I suppose a it's little enough compensation for living in a rather large sauna!

Actually, he lives in a panhandle... the difference is subtle, but the annoying weather is the same

 

Actually, he lives in a panhandle... the difference is subtle, but the annoying weather is the same