On Sun, 13 Aug 2017 16:29:12 -0700 (PDT), Phil Allison <pallison49@gmail.com> wrote:>Phil Hobbs wrote: > >> >> That's a little bit unfair--Phil's worth listening to on the subject of >> audio gear when he's on his meds. >> >> > >** The scheme JL posted *IS* a common audio circuit - the fact the amp is class D seems to have you all going in tiny circles and thinking about SMPS topologies. > >An audio power amp coupled directly to a iron core transformer is something I am very familiar with and so KNOW the issues. > >IMO JD would be wise to drop the class D IC as it creates additional problems and use a class AB linear amp. > >It is obvious that none of you here have a clue. > > >.... Phil >I expect to have to drive reactive loads. Linear amps get very inefficient working in reactive quadrants. I also want to get as much power as I can, over a wide output voltage range, out of a 24 volt wall-wart and a small box without gigantic heat sinks. A speaker is mostly resistive, so is a good load for a linear amp. The only problem I'm seeing is the potential for DC error into the transformer primary causing flux buildup, and the series caps fix that. A linear amp would have the same issue. -- John Larkin Highland Technology, Inc lunatic fringe electronics
class D amp
Started by ●August 11, 2017
Reply by ●August 15, 20172017-08-15
Reply by ●August 15, 20172017-08-15
On Tue, 15 Aug 2017 10:26:04 +0000, Chris <xxx.syseng.yyy@gfsys.co.uk> wrote:>On 08/13/17 23:29, Phil Allison wrote: > >> >> ** The scheme JL posted *IS* a common audio circuit - the fact the amp is class D seems to have you all going in tiny circles and thinking about SMPS topologies. >> >> An audio power amp coupled directly to a iron core transformer is something I am very familiar with and so KNOW the issues. >> >> IMO JD would be wise to drop the class D IC as it creates additional problems and use a class AB linear amp. >> >> It is obvious that none of you here have a clue. >> >> >> .... Phil >> > > >That was my suggestion as well, but why design it if you can buy >a s/hand audio amp for peanuts on ebay, then drive it with an >audio oscillator ?.I already have a Peavey 800 watt stereo amp and some rackmount transformers, but that isn't portable or programmable. And it will eventually die. We'll probably also offer this as a product, an accessory to our synchro and LVDT processors. I haven't found anything like this on the market; if I did, I'd just buy it. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●August 15, 20172017-08-15
On Sun, 13 Aug 2017 08:40:32 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Sun, 13 Aug 2017 12:35:27 +0100, Piglet <erichpwagner@hotmail.com> >wrote: > >>On 13/08/2017 03:30, Jim Thompson wrote: >>> >>> I've successfully kept Ethernet transformers happy by watching the >>> current*time balance in the center-tap. >>> >>> ...Jim Thompson >>> >> >>I like the sound of that. >> >>You mean JL could compare the primary center-tap against supply >>mid-point and feedback to eliminate asymmetry problems? >>My tranny doesn't have a center tap.>>piglet >> > > Not quite, but close. Rather than observing volt-seconds, which is >slow, watch current to/from center-tap for asymmetry, cycle-by-cycle. > > ...Jim ThompsonI'd have to sift milliamps of DC out of amps of varying AC waveforms, and apply a DC correction around the class-D amp somehow. Some series capacitance does that for me. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●August 15, 20172017-08-15
On 8/15/2017 9:34 AM, John Larkin wrote:> On Sun, 13 Aug 2017 08:40:32 -0700, Jim Thompson > <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >> On Sun, 13 Aug 2017 12:35:27 +0100, Piglet <erichpwagner@hotmail.com> >> wrote: >> >>> On 13/08/2017 03:30, Jim Thompson wrote: >>>> >>>> I've successfully kept Ethernet transformers happy by watching the >>>> current*time balance in the center-tap. >>>> >>>> ...Jim Thompson >>>> >>> >>> I like the sound of that. >>> >>> You mean JL could compare the primary center-tap against supply >>> mid-point and feedback to eliminate asymmetry problems? >>> > > My tranny doesn't have a center tap.Is everybody here too lazy to type transformer?
Reply by ●August 15, 20172017-08-15
As with any good design practice, if one defines all the measurable specs up front for performance, cost, reliability, environment and time contraints, one can easily define Design Validation Test plans or DVT to rate the design result. I used to do this for Magnetic HDD design and used non-destructive "margin measurements" to functional failure on critical parameters and acceptance criteria for pass/fail tests. Test format included setup and diagram , 1 page per test. Summary of all results on 1 page. You may want to consider this "motus operandi" in your design projects, such as this. I learned this way from all my past experiences in Aerospace in 70's and working with Japanese Eng.'s in 80's while at Burroughs/Memorex/Unisys. Saturation margin depends on many variables , each contributor may be measured , such as dynamic loads, supply, f, temp, then choose optimal nominal energy density, with desired margin. The energy is stored in the distributed dielectric gaps between magnetic particles, while the saturation heating occurs in the conductive particles. The Remenance depends on initial conditions and current*time integration over each cycle alone with current used for feedback can be applied like a PID feedback loop if one wants to get fancy on increasing energy density stored with feedback for protection, but at what cost?
Reply by ●August 15, 20172017-08-15
On Tue, 15 Aug 2017 07:45:50 -0700 (PDT), Anthony Stewart <tony.sunnysky@gmail.com> wrote:>As with any good design practice, if one defines all the measurable specs up front for performance, cost, reliability, environment and time contraints, one can easily define Design Validation Test plans or DVT to rate the design result. I used to do this for Magnetic HDD design and used non-destructive "margin measurements" to functional failure on critical parameters and acceptance criteria for pass/fail tests. Test format included setup and diagram , 1 page per test. Summary of all results on 1 page. > >You may want to consider this "motus operandi" in your design projects, such as this. I learned this way from all my past experiences in Aerospace in 70's and working with Japanese Eng.'s in 80's while at Burroughs/Memorex/Unisys. >We don't know the needs of all the people who may use or buy our products. And we don't know how any particular specs will affect sales. We don't know the price elasticity of our products. Some fraction of the things that we design (I thought 50%, others claim 75%) never pay off. So we don't have hard performance metrics. We make a thing as good as we reasonably can without getting crazy, and try to incorporate hooks for improving features or specs if people ask for them. The specs and features evolve as the design progresses, which is one reason to stay confused and talk things over for a while before etching boards. Many engineers dislike the confused phase. They want to lock down specs and architectures as soon as possible and enter the implement phase. That is often the path to an inferior product. Somebody claimed that 19 out of 20 newly introduced breakfast cereals are failures. Most restaurants and dot.com startups fail. PT Cruiser is gone. And there was the carefully-researched, focus-group-tested New Coke.>Saturation margin depends on many variables , each contributor may be measured , such as dynamic loads, supply, f, temp, then choose optimal nominal energy density, with desired margin. The energy is stored in the distributed dielectric gaps between magnetic particles, while the saturation heating occurs in the conductive particles. The Remenance depends on initial conditions and current*time integration over each cycle alone with current used for feedback can be applied like a PID feedback loop if one wants to get fancy on increasing energy density stored with feedback for protection, but at what cost?I thought the low-voltage polymer caps with antiparallel diodes, in the primary, was a cute idea. There is a lot of hostility to ideas here; it's hard to brainstorm in public. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●August 15, 20172017-08-15
On Tue, 15 Aug 2017 08:36:51 -0700, John Larkin <jjlarkin@highlandtechnology.com> wrote: [snip]> >Many engineers dislike the confused phase.Not me ;-)>They want to lock down >specs and architectures as soon as possible and enter the implement >phase. That is often the path to an inferior product.Periodically, when I'm not happy with the way a design is going, I scare the crap out of customers by scrapping the design, and starting completely over. But they always end up happy!> >Somebody claimed that 19 out of 20 newly introduced breakfast cereals >are failures. Most restaurants and dot.com startups fail. PT Cruiser >is gone. And there was the carefully-researched, focus-group-tested >New Coke. >[snip] ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, 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'm looking for work... see my website. Thinking outside the box...producing elegant & economic solutions.
Reply by ●August 15, 20172017-08-15
John Larkin wrote...> > I would never use potentially counterfeit Chinese parts > in aerospace gear, or actually in anything that we make.Of course, but they can be useful for quick prototyping. Also the IRS2092 is a rather advanced design, so it's not likely there are counterfeit versions. -- Thanks, - Win
Reply by ●August 15, 20172017-08-15
On Tue, 15 Aug 2017 09:32:12 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Tue, 15 Aug 2017 08:36:51 -0700, John Larkin ><jjlarkin@highlandtechnology.com> wrote: > >[snip] >> >>Many engineers dislike the confused phase. > >Not me ;-) > >>They want to lock down >>specs and architectures as soon as possible and enter the implement >>phase. That is often the path to an inferior product. > >Periodically, when I'm not happy with the way a design is going, I >scare the crap out of customers by scrapping the design, and starting >completely over.Lots of people will continue on a year-til-done design, even if you show them a better thing that can be done in three months. Some potential customers are turned off by expressions of uncertainty; they want absolute confidence and pretty PowerPoint presentations. Not our kind of customer. The good ones, you can brainstorm and get goofy with and invent things together. Dare to be goofy! -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●August 15, 20172017-08-15
On Tue, 15 Aug 2017 09:41:06 -0500, John S <Sophi.2@invalid.org> wrote:>On 8/15/2017 9:34 AM, John Larkin wrote: >> On Sun, 13 Aug 2017 08:40:32 -0700, Jim Thompson >> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>> On Sun, 13 Aug 2017 12:35:27 +0100, Piglet <erichpwagner@hotmail.com> >>> wrote: >>> >>>> On 13/08/2017 03:30, Jim Thompson wrote: >>>>> >>>>> I've successfully kept Ethernet transformers happy by watching the >>>>> current*time balance in the center-tap. >>>>> >>>>> ...Jim Thompson >>>>> >>>> >>>> I like the sound of that. >>>> >>>> You mean JL could compare the primary center-tap against supply >>>> mid-point and feedback to eliminate asymmetry problems? >>>> >> >> My tranny doesn't have a center tap. > > >Is everybody here too lazy to type transformer?Thank you for that valuable technical contribution to class-D amplifier design. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
