Forums

SMPS Long-Term Reliability

Started by Cursitor Doom April 26, 2015
On Sun, 26 Apr 2015 19:00:02 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

> > >-- >Seven Transistor Labs >Electrical Engineering Consultation >Website: http://seventransistorlabs.com >"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote >in message news:a29qja5tm93jsdfspfotpb1fpo4tvvhrv5@4ax.com... >> On Sun, 26 Apr 2015 11:44:10 -0500, "Tim Williams" >> <tiwill@seventransistorlabs.com> wrote: >> >>>The most glaring omission is usually current-mode control (which is >>>absurd >>>if you think about it: the heart of a switching supply is the current >>>through the energy storage inductor, wherever that might be), but if the >>>control loop hasn't cacked in that time, it's probably the same thing as >>>anything else, electrolytics. >>> >>>Tim >> >> You can't necessarily draw such a conclusion about loop control. I >> was using current-mode control with discrete components in the >> 1977-1987 time frame at GenRad Portable Products Division, Phoenix. > >True. And I've done it with all of five* transistors; >http://seventransistorlabs.com/Images/Deadbug_Sch.png > >*TL431 acts like it has a very accurate Vbe. So I'm cheating, so what. ;)
TL431, my favorite jelly-bean part. In your PNG, acting as an OpAmp... did that sort of thing many times.
> >But given the selection of early controller chips (like SG3524 and related >PP types, or MC34063 -- which to be fair, is mostly current controlled in >its usual implementation, but.. ??!), the chances of finding a "good" one >in period equipment seems unlikely. > >Hmm, speaking of blocking oscillators, there was one of those "famously" >in the Apple II. That's a little new against the OP's timeline, but shows >the approach was definitely not unknown. > >Tim
...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Cursitor Doom wrote:

Phil Allison wrote:
> > > ** I see no point to such a vague, sweeping and presumptuous question. > > > > It looks a awful lot like a troll. > > > > Convince me I am wrong - go ahead make my day. > > LOL! Wish I had five bucks for every time you accused some poor, innocent > soul here of being a troll
** Your wish would get you nothing. You did not make my day, so you are trolling as usual. FYI: Posting dopey questions to amuse and draw attention to yourself is trolling. ... Phil
On Sunday, April 26, 2015 at 4:58:09 PM UTC-7, Tim Williams wrote:

[on defects of early SMPS designs]
> > Hmm, speaking of blocking oscillators, there was one of those "famously" > in the Apple II. That's a little new against the OP's timeline, but shows > the approach was definitely not unknown.
And, I STILL see copies of the Apple II design. The last one I had to fix, had no bad components. But the startup was so sensitive/flaky that it had to reform its capacitors before it would work. And, it had to work before it would reform its capacitors. The fix: leave it on overnight. It was working fine in the morning.
"whit3rd" <whit3rd@gmail.com> wrote in message 
news:429ff3de-106c-472a-ae5a-fc162b855983@googlegroups.com...
> And, I STILL see copies of the Apple II design. The last one I had to > fix, > had no bad components. But the startup was so sensitive/flaky that > it had to reform its capacitors before it would work. And, it > had to work before it would reform its capacitors. > > The fix: leave it on overnight. It was working fine in the morning.
On the upside, it's usually the kind of thing that's perfectly okay with that sort of operation (slow start, short protection, etc.). Pretty impressive for ~3 transistors. The basic design has (had?) also seen considerable longevity in home media devices (VCRs, then DVD players), for some reason. Is that a design culture sort of thing? Can't say I've ever designed a VCR, I have no idea. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
On Mon, 27 Apr 2015 18:53:41 -0700, Phil Allison wrote:

> Cursitor Doom wrote: > > Phil Allison wrote: >> >> > ** I see no point to such a vague, sweeping and presumptuous >> > question. >> > >> > It looks a awful lot like a troll. >> > >> > Convince me I am wrong - go ahead make my day. >> >> LOL! Wish I had five bucks for every time you accused some poor, >> innocent soul here of being a troll > > > ** Your wish would get you nothing. > > You did not make my day, so you are trolling as usual. > > FYI: > > Posting dopey questions to amuse and draw attention to yourself is > trolling.
Get help, mate.
Cursitor Doom wrote:

> Phil Allison wrote: > > > Cursitor Doom wrote: > > > > Phil Allison wrote: > >> > >> > ** I see no point to such a vague, sweeping and presumptuous > >> > question. > >> > > >> > It looks a awful lot like a troll. > >> > > >> > Convince me I am wrong - go ahead make my day. > >> > >> LOL! Wish I had five bucks for every time you accused some poor, > >> innocent soul here of being a troll > > > > > > ** Your wish would get you nothing. > > > > You did not make my day, so you are trolling as usual. > > > > FYI: > > > > Posting dopey questions to amuse and draw attention to yourself is > > trolling. > > Get help, mate.
** Get a life, troll. ... Phil