So for bypass-fail alert which can safely detect drop across ballast resistor (R_Bal) of like 2Vac to more than 200Vac I say it doesn't get any simpler than this!


All grounds are referenced to V2 which is totally dedicated PSU based on tiny xfmr (salvaged from old NTSC RF Modulator) + 4pin dip bridge + tantalum filter cap (regulation isn't necessary just for powering LED).

So I realize cuz of mosfet's basically ∞ LF input Z, ckt could just use soft-start PSU w/ line _isolation_ by means of 10Meg resistors in series with both rails! But I definitely don't like ANY Ohmic connection between line and subsystem ckts cuz I say ANY unintended _Earth reference_ is totally bogus design even at μA levels!

Here's circuit description:
So component numbers in diagram are chosen from LTspice's vry limited library and also to humor it's _kinky fetishes_! So plz use descriptions below to understand proper choice of real world parts:

◊M1 should be _logic-level_ input, N channel MOSFET.

◊D1 protects gate of M1 so should have Zener voltage < 5V

◊R2 should be made from 2 equal value resistors connected in series (two 470KΩ is close enough), But plz don't fold them next to each other! Whole point is to increase flash-over immunity (in case of line spikes or HV interference) so just connect them end to end and seal them in heat shrink tube as single linear unit!

Anyhow, R2 limits current and also, along with C2, forms ripple filter for M1 bias (so LED basically has 100% duty-cycle when bypass failure is detected). Now for ppl who want 2 play it REALLY safe u can use 5V MOV in place of C2 cuz inherent capacitance would be in right area AND you'll have OVP for MOSFET gate in case of line spikes too!

Also for ppl wondering why I don't use bigger resistor (like 10MΩ) it's just that high-Z ckts are way more prone to _interference_ by even just weak EMP (like from arcing on other side of room and even nearby high-I switching) and like that! So I say best policy is using smallest reasonable value that doesn't cause loading or current handling issue!

◊R3 is chosen so LED is on for ≥ 250ms after after R_Bal is properly bypassed (just 2 make sure ppl notice it)!

◊_Zload_ means complex impedance of variac and all _down stream_ components including load! So 3Ω is just arbitrary value for simulation!

PS So taking HP's suggestions, I _anchored_ image in my blog set to view by _all visitors_! So hopefully it's readable to guests!

 

I definitely don't like ANY Ohmic connection between line and subsystem ckts cuz I say ANY unintended _Earth reference_ is totally bogus design even at μA levels!

+1000

Very best regards
HP

 

All grounds are referenced to V2 which is totally dedicated PSU based on tiny xfmr

Are you aware that there are isolated, DC-DC converters out there much smaller than a transformer?

Here's one that I use frequently, which translates 5VDC to isolated 12VDC, and it's nice, small and tidy:

It costs less than $4 bucks ... I use it mainly to drive nFet's gates when working at high voltages. There are many more available with other ratios and capacities if you need a different one.

 

@Aleph(0) --- While, of course, your 'bypass failure annunciator' (as drafted above) will function correctly from ~ 2v (RMS) to well beyond 240v (RMS) I am, nonetheless, bound to confess that I don't like it! -- Said objection owing --in no small part-- to the fairly galloping 'inelegance' of its (FAIAP) direct mains-to-source (and, hence, low-Z mains-to-LED) connection... Moreover, although said circuit may not violate the letter of this site's prohibition of direct mains powered LED arrangements -- it is certainly in violation of the spirit of said bylaw.

Granted! -- In principle, your circuit poses no greater hazard than that attending a line-operated Ne2, etc... That said, we must remain cognizant of our readership's rather diverse skill/experience level! --- CIP one does not expect an LED (nor, come to that, its 'auxiliary circuit') to float above Earth/chassis ground at line potential sans significant current limiting...

On a constructive note - I believe I've a 'painless' solution providing true R_Bal-to-circuit isolation all the while leaving your otherwise excellent wide dynamic-range 'EMF detector' wholly intact! Said solution to be elaborated upon as soon as I beg, borrow or steal a moment for some comprehensive 'in vivo' evaluation of same...

Very best regards
HP

PS
@cmartinez --- please know that I too will recommend (albeit, in such case, 'redundant') PSU isolation along with my suggested 'amendment' to @Aleph(0)'s circuit (on the premise that two 'fire-doors' are better than one)

To that end, are you aware of a DC-DC converter unit that will 'take' 9V up to 12V @ ≥ 100mA with reasonable efficiency?

Many, many thanks!
HP

 

To that end, are you aware of a DC-DC converter unit that will 'take' 9V up to 12V @ ≥ 100mA with reasonable efficiency?

There are over 200,000 options to be found at Digikey, all one's gotta do is do a parametric search for the part.

Here's a very convenient candidate.

​

 

Note: Draft at end of post.

I believe I've a 'painless' solution providing true R_Bal-to-circuit isolation all the while leaving your otherwise excellent wide dynamic-range 'EMF detector' wholly intact!

Be it ever so pedestrian - here 'tis -- Note that, owing to employment of a standard (and, hence, continuous mains-isolation 'grade') line-transformer as the 'transducer', redundant power supply isolation is not be required... -- K1 (i.e. the EMF transducer) is implemented via a 100mA 1:5 'step-down' mains transformer of the type commonly encountered in linear 'wall-warts', the PSU circuits of 'mildly retro' corded 'converter boxes', routers, Dial-up and ADSL modems, optical network terminals, etc...

Note to interested parties: Please do not confuse said transformer with the 600Ω tel-line isolation transformers found in 'dial-up' modems and other telephony equipment! -- Such devices are essentially incompatible with 60Hz operation -- as a matter of fact, the rather 'anemic' (i.e. 'iron poor') units found in dial-up modems, tend to begin saturating at Ca. 4mA at 60 Hz! --- Please rest assured that very small power transformers are inexpensive, abundant and available!

Note that a Delon rectifier is implemented such that full indicator (i.e. D2,D3) brilliance is attained at R_Bal drops of no greater than 5V RMS (which being, in part, by way of compensation for the step-down construction of K1 -- (As per my experience, 120V:25V represent far and away the most common -- and, hence, commonly available -- 'miniature' mains transformer configuration) --- And NO! The Delon Cap values (100nF) are NOT typos! At the very low currents involved said circuit --so constructed-- functions splendidly as a low ripple 'pk-pk to DC translator'

As per 'protocol' following is a brief circuit description (But really! -- I should think such should be obvious!)

-A (sinusoidal) AC EMF drop across R_Bal is imposed upon the high impedance primary of K1.
-A (sinusoidal) AC EMF exhibiting a peak magnitude ≈ 1/5 E[primary peak] appears across the secondary.
-A DC EMF ≈ the peak-to-peak value of the secondary EMF (i.e. ≈ 2/5{R_Bal peak]) appears at the output of the Delon circuit.

-As explained by @Aleph(0), D1 holds gate EMFs to safe values (to wit: E{gate} < 7V DC at E{R_Bal} >300V RMS -- (Hence the circuit drafted below will function correctly equipped with a 1:1 transformer [transducer] in place of K1).

Inasmuch as the 'logic-level' MOSFET saturates at E{gs} < 2V, R_Bal drops ≥ 5v guarantee annunciation. --- Please note that significant 'leeway' exists given that R_Bal's continuous 'free air' power handling Spec = 12W (hence ≈ 15V RMS)...

-R3 discharges the Delon caps (and, via R1, M1's gate) such that failure annunciation is appropriately canceled upon establishment of proper bypass conditions.

-R1 lightly ballasts D1 such that a wide E(R_Bal) range (0-300V RMS) may be achieved sans excessive ripple or requirement of 'power handling' (i.e. >100mW) components in the 'bias' circuit...
////////////////////////////////////////////

@cmartinez: Although --as it turns out-- DC-DC conversion/isolation is not required in this case -- Please know that your kind information, references and resources are greatly appreciated and will be permanently referenced in the next revision of my blog -- I'd no idea DC-to-DC conversion (especially 'up conversion' ) had become so elegant - and with such 'robust' isolation figures!


@Aleph(0)
Granting that your absence owes far more to something akin to a 'busman's holiday' than anything like a 'vacation' -- I would, nonetheless, greatly appreciate it were you to make an effort at greater participation here --- On my word! I realize how exasperating [/gross understatement] the 'team' can be -- But then the alternative would have us dwelling in a "fool's paradise"...

With sincere gratitude
HP

Edit at Ca. 21:00 UTC Jan 19 2019 - To correct drafting error (HP).
Edit at Ca. 17:00 UTC May 11 2019 - To update circuit (HP).

 

Hello,

Is the left 100n capacitor shorted?

Bertus

 

Hello,

Is the left 100n capacitor shorted?

Bertus

Fixed! --- Many thanks for the heads-up!

Edit at Jan 19 2019 - To correct drafting error (HP).
Edit at Ca. 17:00 UTC May 11 2019 - To update circuit (HP).


Very best regards
HP

PS -- Inasmuch as I am unable to locate a 'logic level' MOSFET in LTSpice's library, the circuit, as drafted, will not simulate properly (Spec. the annunciation-trigger level will exceed 5V RMS) -- Howbeit real-world operation is as described where the recommended device is employed...

 

Note: Draft at end of post.



Be it ever so pedestrian - here 'tis -- Note that, owing to employment of a standard (and, hence, continuous mains-isolation 'grade') line-transformer as the 'transducer', redundant power supply isolation is not be required... -- K1 (i.e. the EMF transducer) is implemented via a 100mA 1:5 'step-down' mains transformer of the type commonly encountered in linear 'wall-warts', the PSU circuits of 'mildly retro' corded 'converter boxes', routers, Dial-up and ADSL modems, optical network terminals, etc...

Note to interested parties: Please do not confuse said transformer with the 600Ω tel-line isolation transformers found in 'dial-up' modems and other telephony equipment! -- Such devices are essentially incompatible with 60Hz operation -- as a matter of fact, the rather 'anemic' (i.e. 'iron poor') units found in dial-up modems, tend to begin saturating at Ca. 4mA at 60 Hz! --- Please rest assured that very small power transformers are inexpensive, abundant and available!

Note that a Delon rectifier is implemented such that full indicator (i.e. D2,D3) brilliance is attained at R_Bal drops of no greater than 5V RMS (which being, in part, by way of compensation for the step-down construction of K1 -- (As per my experience, 120V:25V represent far and away the most common -- and, hence, commonly available -- 'miniature' mains transformer configuration) --- And NO! The Delon Cap values (100nF) are NOT typos! At the very low currents involved said circuit --so constructed-- functions splendidly as a low ripple 'pk-pk to DC translator'

As per 'protocol' following is a brief circuit description (But really! -- I should think such should be obvious!)

-A (sinusoidal) AC EMF drop across R_Bal is imposed upon the high impedance primary of K1.
-A (sinusoidal) AC EMF exhibiting a peak magnitude ≈ 1/5 E[primary peak] appears across the secondary.
-A DC EMF ≈ the peak-to-peak value of the secondary EMF (i.e. ≈ 2/5{R_Bal peak]) appears at the output of the Delon circuit.

-As explained by @Aleph(0), D1 holds gate EMFs to safe values (to wit: E{gate} < 7V DC at E{R_Bal} >300V RMS -- (Hence the circuit drafted below will function correctly equipped with a 1:1 transformer [transducer] in place of K1).

Inasmuch as the 'logic-level' MOSFET saturates at E{gs} < 2V, R_Bal drops ≥ 5v guarantee annunciation. --- Please note that significant 'leeway' exists given that R_Bal's continuous 'free air' power handling Spec = 12W (hence ≈ 15V RMS)...

-R3 discharges the Delon caps (and, via R1, M1's gate) such that failure annunciation is appropriately canceled upon establishment of proper bypass conditions.

-R1 lightly ballasts D1 such that a wide E(R_Bal) range (0-300V RMS) may be achieved sans excessive ripple or requirement of 'power handling' (i.e. >100mW) components in the 'bias' circuit...
////////////////////////////////////////////

@cmartinez: Although --as it turns out-- DC-DC conversion/isolation is not required in this case -- Please know that your kind information, references and resources are greatly appreciated and will be permanently referenced in the next revision of my blog -- I'd no idea DC-to-DC conversion (especially 'up conversion' ) had become so elegant - and with such 'robust' isolation figures!


@Aleph(0)
Granting that your absence owes far more to something akin to a 'busman's holiday' than anything like a 'vacation' -- I would, nonetheless, greatly appreciate it were you to make an effort at greater participation here --- On my word! I realize how exasperating [/gross understatement] the 'team' can be -- But then then the alternative would have us dwelling in a 'fools paradise'...

With sincere gratitude
HP

Edit at Ca. 21:00 UTC to correct drafting error (HP).

HP that's perfect, TNX! I'm SO looking forward to spending time on here again!


Just so everybody knows, following is off-topic _rant_ I mainly put here 2 explain why I've been scarce since last month and also to reinforce _warning shot_ fired over bow of some outside interests who I know read here. So anyhow NOTHING in the following is referring to EHT project or any ACTIVE AAC member at all!

Here's OT delimiter:
/////

HP so anyhow since I had to TOTALLY redesign Orbitrap to undo oversights of NUMPTIES who think on themselves as engineers, AXN__ lab finally has _functional_ MS. But now I'm going to say something! Orbitrap is not proper instrument for application! Also If they think I'll loan access to my personal QFT facilities they're dreaming! Cuz it's totally not happening!

So anyhow for now I totally withdrew funding from Research until search committee recruits competent staff (I also totally made it clear that personnel isn't my responsibility and that SC's positions are _hanging in the balance_ too !) HP I'm serious! If they don't get their act together I'm totally closing program and foreclosing on facilities! Now to ppl thinking I'm being too demanding all I can say is that my being in role of PI AND financier I have zero patience with ppl who hold PhDs and other advanced degrees in physical science but have zero imagination, creativity and can't even grasp basic math concepts! IMO they are a total waste of space and HP, like u say, also an _indictment of modern education_! So I attended school, earned my degrees and way more important came away with comprehension of subjects! Also I'm like over 20 years younger than a lot of them which means I had way worse education system to navagate! So I'm not expecting anything from anybody beyond what I demand of myself! IMO their whole problem is personal LAZINESS so my advice 2 ppl content to know the _pixels_ and not the _picture_ plz just find subject u have genuine interest in! Cuz life needs 2b more than endless block of _if then_ statements!
/////

So getting back on topic, I'm hoping 2 have time 2b back on here regularly in next few weeks! But I'll definitely make on-topic response to latest posts here this coming weekend!

 

IMO their whole problem is personal LAZINESS

you run the risk of hurting some millennial's feelings with that bluntly executed statement! ... I believe that the PC way of saying the same thing would be "their whole problem is a personal deficiency of automotivation" of which (of course) they're not to blame! ...

 

Just so everybody knows, following is off-topic _rant_ I mainly put here 2 explain why I've been scarce since last month and also to reinforce _warning shot_ fired over bow of some outside interests who I know read here

So let me see now. You think ranting here to non members will change things? There's a movie with sort of the same premise seems like it's called, "Groundhog Day", or something like that.

 

you run the risk of hurting some millennial's feelings with that bluntly executed statement! ... I believe that the PC way of saying the same thing would be "their whole problem is a personal deficiency of automotivation" of which (of course) they're not to blame! ...

Ooooh! Having oft stood in immediate audience to her rants upon the subject - I daresay @Aleph(0)'s annoyance with institutionalized 'kalnienk-mentia' extends to even such 'lofty' ranks as ''Boomers" and, especially, "Gen-X'ers".

Re: Millennials

they're not to blame! ...

I believe @Aleph(0)'s point is that she --as a millennial herself (year of birth = 1992)-- 'managed' to emerge from the travesty that is contemporary education quite nicely -- hence her assertion that those who fall for The Big Lies (prominent among said hype being the alleged adequacy of empiricism/pragmatism, 'hero/icon worship', politicization of 'science', etc...) represent a small (albeit over-represented --'bad PR inducing') abjectly indolent minority among her generation...

FWIW it is my opinion that she makes an inarguable point! There's no denying that we (i.e. older generations) had a much easier time of procuring quality (I daresay real) education! --- Hence the 'extra-special' indefensibility of professionals in our generations 'dropping the ball', as it were!

There's a movie with sort of the same premise seems like it's called, "Groundhog Day", or something like that.

Aye! Seems this entire project has been caught in a 'temporal loop' for nigh on 4 years now --- Methinks that will change following our (prospective) move to 'on-topic' fora! -- By way of analogy, it is said that reducing is easier in the absence of nutrition! IOW when off-topic rambling is off-limits (via management-enforced fiat) -- on-topic progress may be in with a chance!

I'm SO looking forward to spending time on here again!

As am I!

Very best regards
HP

 

on-topic progress may be in with a chance!

Even with so many non members putting/mandating what is said and done? If this is for those non members (mostly) and they are not willing to be openly involved, they should lose their rights to having a say or questioning what is being done. Done to benefit them more than anyone else. Just my old man rant.

 

If this is for those non members (mostly) and they are not willing to be openly involved, they should lose their rights to having a say or questioning what is being done. Done to benefit them more than anyone else...

Indeed! -- While I sympathize with one's reluctance to share/deposit personally identifiable information anywhere on 'the web' (as per @Aleph(0)'s 'mantra' "if Equifax can be hacked anyone can") -- said objection falls upon deaf ears coming from individuals having established social media 'accounts' sans the least thought of security via employment of pseudonyms, etc... Hence my opinion that said reticence owes instead to vanity -- to a distaste for appearing 'ignorant' before the 'public' corollary to making inquiries and/or exhibition of misapprehension --- An attitude I find particularly unfortunate in view of the fact that the majority -- I daresay the vast majority-- of our 'regular' readership is comprised of avid students and credentialed professionals (albeit, Re: the latter, principally in 'peripheral areas') -- Point being: scholars, academicians and credentialed professionals (Spec. practicing physical scientists) know better! Pride and education are utterly immiscible! To be ashamed of 'not knowing' or 'being wrong' is to be ashamed of acquiring knowledge! --- Let it be known that this has been a learning process for us as well!

But to the 'gist' of your (tacit) 'question' (as I understand it): Why do we acknowledge/attempt to work with said 'ingrates'? -- Simply stated - if we don't, maybe no one will

The amount of misinformation --vested in even well respected, 'mainstream' references-- in regards to, for instance, EHT phenomena, bremsstrahlung, IECD topics (and, indeed, 'particle physics' in general) is nothing short of appalling! -- Then too is the exasperating (even if rather intriguing) observation that a significant number of well-studied, alacritious enthusiasts, serious students and practicing professionals regard the subject with a sentiment akin to 'religious ardor' all the while 'disrespecting' same via a 'trade-like' practical approach (i.e. 100% technique, 0% concept, if you will)

Hence our small but conscientious attempt to inject a bit of concept into an area 'hijacked' by the seemingly antipodal likes of 'carnival barkers' and 'utilitarians'...

Even with so many non members putting/mandating what is said and done?

As regards the test/proofing teams -- annoying though their 'bashfulness' is -- their efforts are of significant assistance -- for which we are most grateful! --- Further to that, it is my hope and expectation that this thread's relocation to on-topic fora may ---via the demonstration of our earnestness entailed thereby--- inspire greater on-list participation on the part of all interested parties

Very best regards
HP

 

vanity -- to a distaste for appearing 'ignorant' before the 'public'

To be ashamed of 'not knowing' or 'being wrong' is to be ashamed of acquiring knowledge! --- Let it be known that this has been a learning process for us as well!

Guess that means I have no shame! I openly admit to my ignorance and am learning or at least trying to learn. Even though I have my doubts on some of what has been presented here during this journey.

 

Guess that means I have no shame! I openly admit to my ignorance and am learning or at least trying to learn.

--Emphasis Added--

Better still! -- It means you're without vanity where acquisition of knowledge/assessment of info is at issue

Even though I have my doubts on some of what has been presented here during this journey.

Please know that we genuinely appreciate it! -- Critical evaluation (as opposed to 'rote acceptance') demonstrates your kind interest and attentiveness to the material! -- Then too, discovery of errors/omissions/ 'problem areas' --and/or-- suggested better (or more 'reader friendly') approaches assist to both improve the courses and establish a 'sound' connection with our readers' needs, preferences and (relevant) circumstances.

Very best regards
HP

 

But I'll definitely make on-topic response to latest posts here this coming weekend!

Loudly tapping fingers!

Best regards
HP

 

Loudly tapping fingers!

Best regards
HP

Try not to scratch your nail's polish ... no use angering your manicurist too...

 

Loudly tapping fingers!

Best regards
HP

HP I say only thing I did wrong is setting exact time! Cuz I'm totally sincere abt being back to regular activity on here ASAP! So when I am, catching up on thread and making responses is like u say _1'st order of business_

Try not to scratch your nail's polish ... no use angering your manicurist too...

Cmartinez that's funny cuz even though she wears it herself, HP doesn't like nail polish being on market cuz PPL sometimes use it to cover discolored nail w/o knowing discolorization can be sign of deadly disease subungual melanoma (which btw is less common than winning NY lottery while being struck by lightning!)

Now so I don't get sued here's totally honest disclaimer! Nobody's saying nail polish causes disease! Just that it can hide it and so makes symptom easy 2 ignore or go unnoticed and like that!

 

it can hide it and so makes symptom easy 2 ignore or go unnoticed and like that!

man, what a disappointment... just when I was getting back into the 80's glam rock fashion again!

​