-- please relax!

HP LOL! I say it's getting to look almost like hydro substation!

So being totally serious, main questions I'm getting are abt why ur _wasting space_ with 1.2mH choke at ripple freq of 120Hz (so XL of abt 0.9Ω). So I say it's vry good thing we anticipated that reaction cuz now that ppl on other thread helped me figure out LSpice, I can show skeptical readers even low L choke makes more difference than they think! Which I agree they should know just from formula but since ppl are SO visually oriented I say a picture is sometimes the most effective communication!

acrylic will shatter when you put too much pressure on it while drilling or when you bolt something to it.

Such has long been my experience as well (Re: 'building-center grade' acrylic) -- Hence my reference to LCD 'light guide' panels as 'magic acrylic'

Shortbus I absolutely agree abt normal acrylic being way too brittle to use for structural parts! But _light guide_ acrylic is totally different animal! So I don't understand it at all except to say manufacturers must use additive to enhance optical properties for _light guide_ application that has side effect of making plastic less brittle! So anyhow that's just my guess.

I must agree that polycarbonate is practically perfect in most every way

HP so here's the big question: Is polycarbonate still _practically perfect_ even w/o its top? Sry! That's joke only inveterate old time move fans (like HP and me) can _get_, so I couldn't resist!

While the jocular intent of your remarks does not escape me -- I am, nonetheless, intrigued

How's about this:

Our preferred component choice (15 US $20 banknotes [i.e. $300] included for monetary perspective)...

---VS---


Your (excellent) suggestion of a linear incandescent lamp (US $1.80 [i.e. the cost of a single lamp] included for monetary perspective)...

Um... I begin to see your point

Chastened and rebuked (well, rebuked anyway)

Very best regards
HP

So HP now there's perfect example of what I mean abt pix sometimes being most effective mode of communication! Cuz you could just have said like _resistor costs 166 and 2/3 times more than bulb_ but pic really brings point home!

And most Dales depending on value, are double layer wound to get them in the smaller housing.

Shortbus just for curiosity, are those windings of like _opposite chirality_ to cancel inductance? So o/c that's not advantage for LVPSU project but if so I say those resistors could make nice dummy loads for AF and RF

 

HP so here's the big question: Is polycarbonate still _practically perfect_ even w/o its top? Sry! That's joke only inveterate old time move fans (like HP and me) can _get_, so I couldn't resist!

Ya coulda been a world-class 'riffer' -- but ya wound up here!

Shortbus just for curiosity, are those windings of like _opposite chirality_ to cancel inductance? So o/c that's not advantage for LVPSU project but if so I say those resistors could make nice dummy loads for AF and RF

FWIW I'm interested in that as well -- I suppose I could merely measure the inductance of a few resistors of that style -- unfortunately, given the rather low-resistance values of my stock, I doubt any would feature sufficent 'turns' to render a conclusive result...

Very best regards
HP

 

Shortbus just for curiosity, are those windings of like _opposite chirality_ to cancel inductance?

FWIW I'm interested in that as well -- I suppose I could merely measure the inductance of a few resistors of that style -- unfortunately, given the rather low-resistance values of my stock, I doubt any would feature sufficent 'turns' to render a conclusive result...

Very best regards
HP

HP I say you could just sweep that 20Ω resistor from like 1kHZ to 100MHz with impedance analyzer?

Or being just quick and dirty u could use SWR bridge with like 50MHz signal to see if mismatch corresponds to 20Ω resistive load? So o/c what I'm really saying is just to use test method with higher freq than like typical LCR tracer to make XL more pronounced?

 

@Hypatia's Protege So here's idea I just had abt inrush ballast! Why not just use inductive (instead of resistive) ballast? Cuz that way heating wouldn't be issue if timer got stuck on ballast mode even with heavy load Z? Just sayin'!

 

@Hypatia's Protege So here's idea I just had abt inrush ballast! Why not just use inductive (instead of resistive) ballast?' !

Without wishing to 'rain on your parade', I'm bound to point up a brace of objections presenting themselves immediately to mind -- To Wit:

1) As with the mutual inductors (i.e. variac and isolation transformer) - depending upon instantaneous power angle, the 'ballast inductor' mighn't 'know' it's an inductor at power-up - at which juncture it's sole value as an inrush current limiter would owe to its winding resistance - which being neither 'elegant' nor, IMO, satisfactory.

2) Bypassing said inductor would significantly reduce the ballast bypass contactor's life (owing to high 'field charge' --and, hence, high inductive 'discharge' current-- when bypassed at certain excitation angles/ranges).

HP I say you could just sweep that 20Ω resistor from like 1kHZ to 100MHz with impedance analyzer?

So o/c what I'm really saying is just to use test method with higher freq than like typical LCR tracer to make XL more pronounced?

---Emphasis Added---

I heard a rumor that (neglecting 'resonance effects') stray/parasitic inductive reactance increases with frequency also -- Get it? The difficulty is one of 'contrast' as opposed to magnitude...

Or being just quick and dirty u could...

And risk bringing yet another 'Aleph' into the world!? -- I think I'll pass

Very best regards
HP

PS to all and sundry having a quarrel with my reference to a variac as a 'mutual inductor' -- Puleeeze! Let's agree to disagree! I'm too weary to argue the point (such that it is)

 

Shortbus just for curiosity, are those windings of like _opposite chirality_ to cancel inductance? So o/c that's not advantage for LVPSU project but if so I say those resistors could make nice dummy loads for AF and RF

At the low, 20Ohm , resistance I'd say no. I cut one of those Dales apart years ago to see what was inside, but don't remember the value of it.

 

@Hypatia's Protege sry cuz I don't have time to handle this right now so I just thought u should know AJ is telling ppl on alpha team that _bleeder_ resistor is bad idea cuz it gives false sense of security cuz it can fail open.

So I say that's just dumb cuz on-board volt meter is indication of residual charge on filter caps ppl should be watching anyhow! Also adjusting unloaded PSU voltage w/o bleeder load would be basically impossible cuz downward adjustments would take > 1 Hr to stabilize!

HP I say AJ is up to old tricks and shouldn't be allowed back on alpha-test staff! So I know u think he's harmless clown but I say _comic relief_ and safety are vry dangerous mix!

At the low, 20Ohm , resistance I'd say no.

Shortbus Tnx! So you mentioning dual winding has me interested enough to find like >= 100Ω and sweep it just 2 see if windings are magnetically opposed! Cuz high power _Dale type_ resistors are vry common on surplus industrial Equip. so they could be vry economical source of RF dummy loads if they're wound 2b net non-inductive!

 

HP I totally like your idea abt building just utilitarian 1.24V -100V adjustable linear regulator as like external _accessory_ for LVPSU! So main problem I anticipate is ppl forgetting 2b vry careful to set LVPSU voltage high enough to prevent regulator dropout during heavy load but also low enough to keep regulator in _safe area_ during light load! Cuz otherwise it's just like ur always saying! Instead of regulated DC, Lm338 SA protection will make output look like relaxation Osc sawtooth!

So just IMO, only other possible problem is 100 milliOhm emitter resistors (for pass BJTs) could be hard to source?

PS So for ppl confused abt using 40V Max regulator for 100V:
Vin(Max) Spec is just Reg chip In to Out terminal voltage limit which isn't problem for design of applications needing higher Output to Ground voltage (except that it limits regulator _swing_ to like 38.76V) So as extreme example u could set up 1,000V regulator but circuit could only have control over < 39V so that would be totally silly but for 100V on high current supply it's no problem!

 

@Hypatia's Protege When u have time (hopefully by weekend?) plz upload schematic of LVPSU inrush limiter circuit!

So 4 ppl who are curious I can try to explain how HP's PFail detector/inrush limiter works but nobody gets it (which just means I'm poor _explainer_ not that ur poor listeners cuz whole world can't be out of step with Aleph)

So anyhow here's description:

◊Train of 50% d/c, 8.3ms square wave pulses is derived from half-wave rectified line signal (through magnetic stepdown isolation transformer for safety).

◊Pulses reset _detection one-shot_ which is set to time-out in just over 8.3ms.

◊If pulse isn't received b4 _detection one-shot_ times out, it means power was interrupted, so _detection one-shot_ resets (ultra-fast reset) _ballast timer one-shot_ to reinitialize _ballast cycle_.

So huge advantage of HP's PFail detection circuit is it's basically immune to noise and line voltage fluctuation but vry sensitive to protractive phase discontinuities which is whole point!

Other advantage is circuit has just easily found vry common parts like general purpose BJTs, a couple 555 timers (which DON'T need 2b cmos version!), general purpose diodes and an opto-isolated triac! So easy 2 find and easy 2 replace if it gets _insulted_ by EHT PSU!

Sry to ppl who don't like a lot of formatting but I say it can help comprehension!

 

When u have time (hopefully by weekend?) plz upload schematic of LVPSU inrush limiter circuit!

Will do! -- FWIW I've likewise created and uploaded (to my blog) an LM7809 model such that I may draft and attach a working, highly 'faithful', LtSpice '.ASC' simulation of the inrush limiter (in addition to screen captures)

I expect to 'up' the 'soft start' circuit Sun/early Mon (i.e. pending exhaustive 'in vivo' evaluation) --- Meanwhile, the curious are welcome to 'play with'/ 'rip on' the LM7809 model to their heart's content

Best regards
HP

 

@Hypatia's Protege b4 u attach .asc file for how you're calling _soft start_ circuit, I say it would be vry good idea 2 see if there's way of making .asc file automatically use your 7809 model! Cuz Ryan, Melissa and JC have same file as on your blog but these are steps they totally have 2 go through to get it to work:

◊Open LtSpice
◊Open your _LM7809.cir_ netlist file
◊Right click on subckt name
◊Select _create symbol_ from drop down
◊Edit auto-created symbol to smaller size
◊Save it to library
◊Select it from _AutoGenerated component_ folder
◊Paste it into schematic (which they'll have to delete and repaste to your .asc cuz transferring .asc from one LtSpice installation 2 another w/o model _breaks_ reference

So anyhow I say that's a lot of p!$$ing around for ppl who aren't totally into spice

HP now b4 u say _ppl not into spice prolly don't have it installed anyway_ all I can say is most ppl I know who are into electronics have simulator installed but vry few of them know how 2 use it beyond drafting and running schematics!

So all I'm saying is if there's any way to make .asc (or whatever file) automatically include your 3'rd party model so it just RUNS on other ppl's installations w/o all the hassle that would be VRY nice!

PS like all other posts on this thread THIS IS OPEN DISCUSSION/QUESTION (not just 2 HP) cuz she's basically spice newbie and I definitely am! So anybody reading this who has suggestion please share!

 

@Hypatia's Protege b4 u attach .asc file for how you're calling _soft start_ circuit, I say it would be vry good idea 2 see if there's way of making .asc file automatically use your 7809 model! Cuz Ryan, Melissa and JC have same file as on your blog but these are steps they totally have 2 go through to get it to work:

◊Open LtSpice
◊Open your _LM7809.cir_ netlist file
◊Right click on subckt name
◊Select _create symbol_ from drop down
◊Edit auto-created symbol to smaller size
◊Save it to library
◊Select it from _AutoGenerated component_ folder
◊Paste it into schematic (which they'll have to delete and repaste to your .asc cuz transferring .asc from one LtSpice installation 2 another w/o model _breaks_ reference

So anyhow I say that's a lot of p!$$ing around for ppl who aren't totally into spice

HP now b4 u say _ppl not into spice prolly don't have it installed anyway_ all I can say is most ppl I know who are into electronics have simulator installed but vry few of them know how 2 use it beyond drafting and running schematics!

So all I'm saying is if there's any way to make .asc (or whatever file) automatically include your 3'rd party model so it just RUNS on other ppl's installations w/o all the hassle that would be VRY nice!

PS like all other posts on this thread THIS IS OPEN DISCUSSION/QUESTION (not just 2 HP) cuz she's basically spice newbie and I definitely am! So anybody reading this who has suggestion please share!

Agreed! there must be an easier way! --- So here's the plan:

I'll post a capture of the 'SoftStart' schematic (accompanied by a cursory circuit description), the associated Ltspice schematic file (i.e. '.asc') and the LM7809's model/'netlist' in textual format (as well as a link to the 'subckt' file residing in my blog) to this thread. -- Thence an inquiry to the 'General Electronics Chat' forum Re: possible 'portability' of third-party component models (as per your concerns expressed in post #1588) --- FWIW I feel inquiries are best 'formed' via specific/explicit examples of the issues at hand -- hence my abeyance pending drafting of the schematic containing the model...

Please expect said posts sometime tomorrow (Monday)...

Very best regards
HP

 

Hp it's all goin' now! Thanx!

 

Good deal! -- Still another problem to 'work out' is most distinctly not what I needed at this time!

Very best regards
HP

PS -- Please try uploading the file{s} Aleph 'E-ed' you (to her thread on 'feedback and suggestions) -- many advance thanks!

 

Been looking at that.

PS -- Please try uploading the file{s} Aleph 'E-ed' you (to her thread on 'feedback and suggestions) -- many advance thanks!

Sure thing! But Flash is strictly verboten for me! I can try flashless uploads though!

 

Please try uploading the file{s} Aleph 'E-ed' you (to her thread on 'feedback and suggestions)

Done!

On the subject of spice models:

◊Paste it into schematic (which they'll have to delete and repaste to your .asc cuz transferring .asc from one LtSpice installation 2 another w/o model _breaks_ reference

Hey Aleph! It's not exactly like that! Lts automatically deletes the "missing" model's symbol from the schematic at load time! Happy days! Here, check it out, not that it makes a lick of difference of course.

I'll post a capture of the 'SoftStart' schematic (accompanied by a cursory circuit description)

I'm looking forward to that, Hp! It's all Greek to me! Who would have thought 555 circuitry could be so complicated?

Thanks for your help! I was getting that lone wolf feeling myself

 

I'll post a capture of the 'SoftStart' schematic (accompanied by a cursory circuit description)

I'm looking forward to that, Hp! It's all Greek to me! Who would have thought 555 circuitry could be so complicated?

I'm on it! -- FYI The principal remaining area of 'in vivo' investigation lies in analysis of actual LM78XX behaviour below E(Drop out) conditions -- Specifically; upon abrupt loss of excitation (to K1), we want to see E(C5)'s decay pass U2 such that the system remains 'alive' long enough to assure full discharge of C1 and C2 (10 ms should be quite sufficient) -- while I cannot imagine difficulty in said regard -- It is, nonetheless, my stance that 'reality testing' is obligatory --in any event-- but especially in the land O' proprietary 'black boxes' (CIP LM78XX '3-terminal' linear regulators)!

Very best regards
HP

PS -- Hey @Jazz2C - Not to 'snap you off' -- Howbeit I request that in future you please refrain from linking attachments to non-public blog entries. -- Please understand, such entries are initially 'private' (i.e. temporally restricted to view only by certain development team members) for their 'preliminary' nature. As you may well imagine, liability to confusion owed to multiple 'revisions' of suggested circuitry/techniques 'floating about' is a hassle we and our long-suffering readers can well live without!

 

ATTENTION -- To any having viewed the preliminary schematic file (injudiciously linked by @Jazz2C in post 1593) -- please disregard the output scheme (i.e. inversion via PNP)!

Ya see - I 'done forgot' the 555's high-level output doesn't attain to the positive rail -- and LtSpice refused to remind me (wah!) -- Thus 'real-world' unacceptably narrow 'margins'... --- No worries! 'Tis nothing a brace of NPNs can't remedy...

I yet expect to post (a proper) schematic/circuit description today/early tomorrow morning -- time permitting

Very best regards
HP

 

@Hypatia's Protege b4 u attach .asc file for how you're calling _soft start_ circuit, I say it would be vry good idea 2 see if there's way of making .asc file automatically use your 7809 model! Cuz Ryan, Melissa and JC have same file as on your blog but these are steps they totally have 2 go through to get it to work:

◊Open LtSpice
◊Open your _LM7809.cir_ netlist file
◊Right click on subckt name
◊Select _create symbol_ from drop down
◊Edit auto-created symbol to smaller size
◊Save it to library
◊Select it from _AutoGenerated component_ folder
◊Paste it into schematic (which they'll have to delete and repaste to your .asc cuz transferring .asc from one LtSpice installation 2 another w/o model _breaks_ reference

So anyhow I say that's a lot of p!$$ing around for ppl who aren't totally into spice

HP now b4 u say _ppl not into spice prolly don't have it installed anyway_ all I can say is most ppl I know who are into electronics have simulator installed but vry few of them know how 2 use it beyond drafting and running schematics!

So all I'm saying is if there's any way to make .asc (or whatever file) automatically include your 3'rd party model so it just RUNS on other ppl's installations w/o all the hassle that would be VRY nice!

PS like all other posts on this thread THIS IS OPEN DISCUSSION/QUESTION (not just 2 HP) cuz she's basically spice newbie and I definitely am! So anybody reading this who has suggestion please share!

Yer so purty......oh, scuze me...what were we talking about?

 

Yer so purty......oh, scuze me...what were we talking about?

I daresay it'd be significantly 'purtier' was there a method of automatically importing 3'rd party component models when loading schematic files containing references thereto

Best regards
HP