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From: George Herold on 23 Dec 2009 16:59 On Dec 23, 2:54 pm, "Paul Hovnanian P.E." <p...(a)hovnanian.com> wrote: > Phil Hobbs wrote: > > On 12/22/2009 3:04 PM, Paul Hovnanian P.E. wrote: > >> Leon wrote: > > >>> On 21 Dec, 17:30, Jim Thompson<To-Email-Use-The-Envelope-I...(a)My-Web- > >>> Site.com/Snicker> wrote: > >>>> On Mon, 21 Dec 2009 11:23:43 -0600, "amdx"<a...(a)knology.net> wrote: > > >>>>> "Jim Thompson"<To-Email-Use-The-Envelope-I...(a)My-Web-Site.com/Snicker> > >>>>> wrote in messagenews:c73vi59928raaaseeo0spcb17vut4ddmpj(a)4ax.com... > >>>>>> On Sun, 20 Dec 2009 23:34:41 -0600, "amdx"<a...(a)knology.net> wrote: > > >>>>>> [snip] > > >>>>>>> Hey Graham, > >>>>>>> I reposted a graph from Fred Bartoli on > >>>>>>> alt.binaries.schematics.electronic, it shows > >>>>>>> inductance dropping with decreasing drive voltage. It doesn't go low > >>>>>>> enough > >>>>>>> though. > >>>>>>> Mike > > >>>>>> Sonnova gun! I wonder what might be causing that? > > >>>>>> Get out your textbooks ;-) > > >>>>>> ...Jim Thompson > >>>>> Causing what ? This is my third attempt at finding out if my > >>>>> postulation > >>>>> has any merit at all. > >>>>> I've been told forget it, just build the transformer. > >>>>> It is just a curiosity for me, I have used the same core at 300 watts > >>>>> power > >>>>> levels and at microwatt levels. > >>>>> Would it have been a better transformer at lower frequencies if I had > >>>>> added more turns. I don't know and > >>>>> I have know way to measure microvolts > >>>>> Note his graph only goes down to 2Vrms, I'd like to see a graph down > >>>>> to 2 microvolts. > >>>>> Hey Jim, I'm a little surprised at your response, is Phil rubbing off > >>>>> on > >>>>> you? > >>>>> Have a drink of fine wine on me :-) > >>>>> Mike > > >>>> I was just pointing out that the effect is not unexpected. Inductance > >>>> is proportional to B/H. > > >>>> ...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 | > > >>>> Help save the environment! > >>>> Please dispose of socialism properly! > > >>> I've seen a VCO circuit using DC current through a winding on a > >>> ferrite core to control the frequency. > > >>http://en.wikipedia.org/wiki/Magnetic_amplifier > > >> I have a couple of old (discrete transistor) power supplies that use a > >> form of mag amp to control the voltage output from the main transformer > >> so as to reduce the series transistor dissipation. > > > Mag amps are _cool_. Slow, bulky, and heavy, but bulletproof and highly > > effective. > > Not much space for them left in today's technology. But its sad to see how > many people have forgotten about (or never learned) the principles behind > this kind of stuff. > > -- > Paul Hovnanian p...(a)hovnanian.com > ---------------------------------------------------------------------- > Have gnu, will travel.- Hide quoted text - > > - Show quoted text - Yup, I'd never heard of them. The wiki article was not much help. Do you have any good references? George H.
From: Tim Williams on 23 Dec 2009 23:09 "George Herold" <ggherold(a)gmail.com> wrote in message news:e82019af-a2e9-4765-8d97-fd7827e8438a(a)d10g2000yqh.googlegroups.com... > Yup, I'd never heard of them. The wiki article was not much help. Do > you have any good references? I have a copy of, Paul Mali, _Magnetic Amplifiers / Principles and Applications_, John F. Rider Publisher, Inc. (1960). It shows operation and use well enough that you could put one together, but it's not a nuts-and-bolts thing where you can design a mag amp from B-H curves and circuit values and such. If you can find a copy (library or online?), it's a worthwhile introduction. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: Paul Hovnanian P.E. on 28 Dec 2009 18:28 George Herold wrote: > On Dec 23, 2:54 pm, "Paul Hovnanian P.E." <p...(a)hovnanian.com> wrote: >> Phil Hobbs wrote: >> > On 12/22/2009 3:04 PM, Paul Hovnanian P.E. wrote: >> >> Leon wrote: >> >> >>> On 21 Dec, 17:30, Jim Thompson<To-Email-Use-The-Envelope-I...(a)My-Web- >> >>> Site.com/Snicker> wrote: >> >>>> On Mon, 21 Dec 2009 11:23:43 -0600, "amdx"<a...(a)knology.net> wrote: >> >> >>>>> "Jim >> >>>>> Thompson"<To-Email-Use-The-Envelope-I...(a)My-Web-Site.com/Snicker> >> >>>>> wrote in messagenews:c73vi59928raaaseeo0spcb17vut4ddmpj(a)4ax.com... >> >>>>>> On Sun, 20 Dec 2009 23:34:41 -0600, "amdx"<a...(a)knology.net> >> >>>>>> wrote: >> >> >>>>>> [snip] >> >> >>>>>>> Hey Graham, >> >>>>>>> I reposted a graph from Fred Bartoli on >> >>>>>>> alt.binaries.schematics.electronic, it shows >> >>>>>>> inductance dropping with decreasing drive voltage. It doesn't go >> >>>>>>> low enough >> >>>>>>> though. >> >>>>>>> Mike >> >> >>>>>> Sonnova gun! I wonder what might be causing that? >> >> >>>>>> Get out your textbooks ;-) >> >> >>>>>> ...Jim Thompson >> >>>>> Causing what ? This is my third attempt at finding out if my >> >>>>> postulation >> >>>>> has any merit at all. >> >>>>> I've been told forget it, just build the transformer. >> >>>>> It is just a curiosity for me, I have used the same core at 300 >> >>>>> watts power >> >>>>> levels and at microwatt levels. >> >>>>> Would it have been a better transformer at lower frequencies if I >> >>>>> had added more turns. I don't know and >> >>>>> I have know way to measure microvolts >> >>>>> Note his graph only goes down to 2Vrms, I'd like to see a graph >> >>>>> down to 2 microvolts. >> >>>>> Hey Jim, I'm a little surprised at your response, is Phil rubbing >> >>>>> off on >> >>>>> you? >> >>>>> Have a drink of fine wine on me :-) >> >>>>> Mike >> >> >>>> I was just pointing out that the effect is not unexpected. >> >>>> Inductance is proportional to B/H. >> >> >>>> ...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 | >> >> >>>> Help save the environment! >> >>>> Please dispose of socialism properly! >> >> >>> I've seen a VCO circuit using DC current through a winding on a >> >>> ferrite core to control the frequency. >> >> >>http://en.wikipedia.org/wiki/Magnetic_amplifier >> >> >> I have a couple of old (discrete transistor) power supplies that use a >> >> form of mag amp to control the voltage output from the main >> >> transformer so as to reduce the series transistor dissipation. >> >> > Mag amps are _cool_. Slow, bulky, and heavy, but bulletproof and >> > highly effective. >> >> Not much space for them left in today's technology. But its sad to see >> how many people have forgotten about (or never learned) the principles >> behind this kind of stuff. >> >> -- >> Paul Hovnanian p...(a)hovnanian.com >> ---------------------------------------------------------------------- >> Have gnu, will travel.- Hide quoted text - >> >> - Show quoted text - > > Yup, I'd never heard of them. The wiki article was not much help. Do > you have any good references? Nothing good specific to mag amps. But they do get some coverage in many of the older handbooks I've run across. -- Paul Hovnanian paul(a)hovnanian.com ---------------------------------------------------------------------- Have gnu, will travel.
From: Jan Panteltje on 30 Dec 2009 10:48
On a sunny day (Wed, 30 Dec 2009 07:32:11 -0800) it happened Fred Abse <excretatauris(a)invalid.invalid> wrote in <pan.2009.12.30.10.56.49.256851(a)invalid.invalid>: >On Mon, 28 Dec 2009 15:28:49 -0800, Paul Hovnanian P.E. wrote: > >> Nothing good specific to mag amps. But they do get some coverage in many of >> the older handbooks I've run across. > >http://www.ferroxcube.com/appl/info/square.pdf Nice. |