Maintaining a Vbe Multiplier's bias value
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From: miso on 9 Feb 2010 23:52 On Feb 9, 6:49 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My-Web- Site.com> wrote: > On Tue, 09 Feb 2010 02:44:31 -0800, Jon Kirwan > > > > <j...(a)infinitefactors.org> wrote: > >On Mon, 8 Feb 2010 18:23:16 -0800 (PST), "m...(a)sushi.com" > ><m...(a)sushi.com> wrote: > > >><snip> > >>Less words and real schematics would get you more readers. [The only > >>thing worse than ascii equations are ascii schematics.] > > >ASCII is what I'll post. It's the only way to get them > >archived or properly posted to a text newsgroup. I no longer > >have access to the binary for schematics, sadly. If I lose > >some people because they cannot manage fixed-spaced fonts, I > >guess I lose them. I could place links up on my domain, I > >suppose. But in this case, the schematics are really very > >basic and not overly burdensome in ASCII. Besides, Win Hill > >posted some really nice examples here, before. Folks seemed > >to live with that. Not sure why you are picking on me, here. > > >>In any event, just google improved vbe multiplier. I've seen all sorts > >>of circuits published to get lower impedance at the nodes. > > >Okay. I'll do that if folks here aren't interested at all in > >talking about it. > > >Jon > > Miso is all blabber and no content... best if ignored ;-) > > ...Jim Thompson > -- > | James E.Thompson, CTO | mens | > | Analog Innovations, Inc. | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | Phoenix, Arizona 85048 Skype: Contacts Only | | > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > | E-mail Icon athttp://www.analog-innovations.com| 1962 | > > I love to cook with wine. Sometimes I even put it in the food. Right. Maybe I'll get another job of yours to fix.
From: miso on 9 Feb 2010 23:55 On Feb 9, 2:44 am, Jon Kirwan <j...(a)infinitefactors.org> wrote: > On Mon, 8 Feb 2010 18:23:16 -0800 (PST), "m...(a)sushi.com" > > <m...(a)sushi.com> wrote: > ><snip> > >Less words and real schematics would get you more readers. [The only > >thing worse than ascii equations are ascii schematics.] > > ASCII is what I'll post. It's the only way to get them > archived or properly posted to a text newsgroup. I no longer > have access to the binary for schematics, sadly. If I lose > some people because they cannot manage fixed-spaced fonts, I > guess I lose them. I could place links up on my domain, I > suppose. But in this case, the schematics are really very > basic and not overly burdensome in ASCII. Besides, Win Hill > posted some really nice examples here, before. Folks seemed > to live with that. Not sure why you are picking on me, here. > > >In any event, just google improved vbe multiplier. I've seen all sorts > >of circuits published to get lower impedance at the nodes. > > Okay. I'll do that if folks here aren't interested at all in > talking about it. > > Jon There are all sorts of free places to post images. Imageshack comes to mind. I just lose interest if I have to look at ascii circuits. You realize you can just string diodes. Nobody says you have to VBE multiply. It's just one of many biasing techinques.
From: miso on 9 Feb 2010 23:58 On Feb 9, 12:18 am, Jon Kirwan <j...(a)infinitefactors.org> wrote: > On Mon, 8 Feb 2010 23:47:24 -0800 (PST), "m...(a)sushi.com" > > <m...(a)sushi.com> wrote: > >Have you read Randy Slone's power amplifier book? This stuff really > >isn't rocket science. Nor is AB. ;-) > > I haven't. It's not rocket science. But it is interesting > at my level. > > ><http://www.amazon.com/High-Power-Audio-Amplifier-Construction-Manual/ > >dp/0071599258/ref=dp_ob_title_bk> > > I'll look, but the title appears more on the contruction > side. I am using this to educate myself a little better. > > >The black art is all in assembly, protection circuitry, and making > >sure it starts up cleanly. [Most engineers never look at start up, so > >you get designs that thump when you power them. I have lots of gear > >with power-on thumps.] > > I recall reading of a recommendation suggesting that all > electronic devices use less than 1W when on, but not > performing their intended application. This would also seem > to require a little added effort to achieve, as well. But I > take your point. > > >I'd pick one of his MOS designs. Bipolar designs often have good > >intentions, but ring like a bell. MOS is mushy, but predictably mushy. > > I'm still learning about BJTs. In fact, that's what this is > about for me. MOS later. ICs later. BJTs now. > > Jon There is plenty of circuit design in the book. It is the assembly stuff (ground loops, thermal tracking, etc.) that people screw up. Anyway, I'd wait for the new edition.
From: miso on 10 Feb 2010 00:03 On Feb 9, 2:52 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > On Tue, 9 Feb 2010 23:38:06 +0100, "Ban" <bans...(a)web.de> > wrote: > > > > >"Jon Kirwan" <j...(a)infinitefactors.org> schrieb im Newsbeitrag > >news:8te2n5llb72tgv03g653ajqjf360m3mc06(a)4ax.com... > >> On Mon, 8 Feb 2010 18:23:16 -0800 (PST), "m...(a)sushi.com" > >> <m...(a)sushi.com> wrote: > > >>><> > >> Okay. I'll do that if folks here aren't interested at all in > >> talking about it. > > >BS, a couple of good answers have come. > > Agreed. We are past that question. > > >Jon, you should read this book, bit torrentwise > >Audio Power Amplifier Design Handbook, 4th Ed. - (Malestrom) > >by Doug Self, one of the deeper going but still very practical publications, > >you'll love it. > >Ban > > I just received a copy of the 5th edition, today. I'll > start, though the author says that it assumes a certain level > of prior training. And skimming through, I agree. > > Jon Self has published many papers too if you have access to an engineering library. I think his stuff is worth reading. Nelson Pass runs a DIY forum http://www.passdiy.com/ Pass is up there with Levinson, and miles above any Arizona designer.
From: Jon Kirwan on 10 Feb 2010 01:13
On Tue, 9 Feb 2010 20:58:39 -0800 (PST), "miso(a)sushi.com" <miso(a)sushi.com> wrote: >On Feb 9, 12:18�am, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> On Mon, 8 Feb 2010 23:47:24 -0800 (PST), "m...(a)sushi.com" >> >> <m...(a)sushi.com> wrote: >> >Have you read Randy Slone's power amplifier book? This stuff really >> >isn't rocket science. Nor is AB. ;-) >> >> I haven't. �It's not rocket science. �But it is interesting >> at my level. >> >> ><http://www.amazon.com/High-Power-Audio-Amplifier-Construction-Manual/ >> >dp/0071599258/ref=dp_ob_title_bk> >> >> I'll look, but the title appears more on the contruction >> side. �I am using this to educate myself a little better. >> >> >The black art is all in assembly, protection circuitry, and making >> >sure it starts up cleanly. [Most engineers never look at start up, so >> >you get designs that thump when you power them. I have lots of gear >> >with power-on thumps.] >> >> I recall reading of a recommendation suggesting that all >> electronic devices use less than 1W when on, but not >> performing their intended application. �This would also seem >> to require a little added effort to achieve, as well. �But I >> take your point. >> >> >I'd pick one of his MOS designs. Bipolar designs often have good >> >intentions, but ring like a bell. MOS is mushy, but predictably mushy. >> >> I'm still learning about BJTs. �In fact, that's what this is >> about for me. �MOS later. �ICs later. �BJTs now. >> >> Jon > >There is plenty of circuit design in the book. It is the assembly >stuff (ground loops, thermal tracking, etc.) that people screw up. >Anyway, I'd wait for the new edition. Okay, will do. Turns out the 5th edition of Self's book on amplifiers contains many typos. Lots of references to parts that aren't in the schematic or clearly are not the one under discussion. Same with some of the terms in equations. I'm correcting as I go. Jon |