On Tuesday, November 3, 2015 at 10:03:19 AM UTC-8, Piotr Wyderski wrote:> You don't need to challenge me, I have exactly the same > experience after nontrivial amount of googling. There's > nothing about it.I recall seeing (about 10yrs ago) a ref to math showing that it's not possible; that even the ideal case, mag amp operating point is outside the gain/phase for oscillation. I didn't look up the ref though. It was in an article on historical development of electronics, claiming that the first oscillators had to wait for vacuum tubes, since even though mag amps existed earlier, oscillators weren't possible. (But even Faraday coulda made one, if he had Nyle Steiner's burned zinc oscillator.) Also: "impractical" means that hobbyists do it all the time for laughs, while "impossible" means that no hobbyist has succeeded, ever. Separate topic: is an all-inductors diode possible, using magnet-biased saturable reactors? I recall a Tesla patent claiming this. If real, why all the rotary converters, and why were selenium or copper-oxide rectifiers such a big deal?
Magamp oscillator
Started by ●November 3, 2015
Reply by ●November 5, 20152015-11-05
Reply by ●November 5, 20152015-11-05
On Thursday, 5 November 2015 07:30:05 UTC, Bill Beaty wrote:> On Tuesday, November 3, 2015 at 10:03:19 AM UTC-8, Piotr Wyderski wrote:> > You don't need to challenge me, I have exactly the same > > experience after nontrivial amount of googling. There's > > nothing about it. > > I recall seeing (about 10yrs ago) a ref to math showing that it's not possible; that even the ideal case, mag amp operating point is outside the gain/phase for oscillation. I didn't look up the ref though.how is that possible? If you have gain you only need add R&C to get time shift aka phase shift.> It was in an article on historical development of electronics, claiming that the first oscillators had to wait for vacuum tubes, since even though mag amps existed earlier, oscillators weren't possible. (But even Faraday coulda made one, if he had Nyle Steiner's burned zinc oscillator.)arc oscillators came before vacuum tubes, relying on negative reistance. 'singing arc.' Not to be confused with spark gap technology. And fwiw there were also electromechanical oscillators such as bells, relays, etc well before valves.> Also: "impractical" means that hobbyists do it all the time for laughs, while "impossible" means that no hobbyist has succeeded, ever. > > Separate topic: is an all-inductors diode possible, using magnet-biased saturable reactors?Inductor rectifiers were one of the standard types in the early days of radio> I recall a Tesla patent claiming this. If real, why all the rotary converters, and why were selenium or copper-oxide rectifiers such a big deal?inductor rectifiers were a relatively reliable tech, but had poor sensitivity. How would you get mere millivolts to cause a significant shift in an inductor's operating point. NT
Reply by ●November 5, 20152015-11-05
On Wed, 4 Nov 2015 23:29:59 -0800 (PST), Bill Beaty <billb@eskimo.com> wrote: <Snip>>Separate topic: is an all-inductors diode possible, using magnet-biased saturable reactors? I recall a Tesla patent claiming this. If real, why all the rotary converters, and why were selenium or copper-oxide rectifiers such a big deal?The 'set' and 'reset' reactors are, in their extreme control settings, biased to allow current flow in one direction only. They require a non-reversible current during their control phase, or in a coupled control winding which is only really practical using a synchronous switch or rectifier. One maintains unidirectional current to keep the part in saturation prior to application of reverse voltseconds, the other applies restting voltseconds only, to avoid conduction in the forward phase. Energy is derived for oontrol either from the source input, or the (un)regulated output - for wider control (or blocking voltsecond) range, both control methods can be applied to the same part. Kotlarewski (sp) in Ottawa published a definitive article on these in the 90s. A certain amount of self-maintained bias can be induced by placing hard magnetic material in series with the flux path, but these tend to be mechanically difficult to construct, short-lived,lossy and of low relative permeability. RL
Reply by ●November 5, 20152015-11-05
On Wednesday, November 4, 2015 at 11:30:05 PM UTC-8, Bill Beaty wrote:> Separate topic: is an all-inductors diode possible, using magnet-biased saturable reactors? I recall a Tesla patent claiming this. If real, why all the rotary converters, and why were selenium or copper-oxide rectifiers such a big deal?A rectifier, with an AC source, produces DC EMF; but any magnetic field that produces in a winding a DC EMF, must have d(flux)/dt ~= dotproduct( (area) ,dB/dt ) >0 in a net average over time. That's a ramp in B that never every decreases: you can not do that, over any sufficiently long period of time the B field will exceed your magnetic material limits (or current supply capability, or material strength limits). The best you could do, is with some moving-parts switching to reverse a winding direction (the commutator on a DC generator reverses the winding polarity); so an AC motor/DC generator or other 'rotary converter'. That doesn't rely on the dB/dt to be always-increasing, it changes the orientation of the 'area' and flips the sign in the dot product so that the product is never negative.
Reply by ●November 5, 20152015-11-05
On Thursday, 5 November 2015 21:08:03 UTC, whit3rd wrote:> On Wednesday, November 4, 2015 at 11:30:05 PM UTC-8, Bill Beaty wrote: > > > Separate topic: is an all-inductors diode possible, using magnet-biased saturable reactors? I recall a Tesla patent claiming this. If real, why all the rotary converters, and why were selenium or copper-oxide rectifiers such a big deal? > > A rectifier, with an AC source, produces DC EMF; but any magnetic field > that produces in a winding a DC EMF, must have > > d(flux)/dt ~= dotproduct( (area) ,dB/dt ) >0 > > in a net average over time. That's a ramp in B that never every decreases: you can not > do that, over any sufficiently long period of time the B field will exceed your magnetic > material limits (or current supply capability, or material strength limits). > > The best you could do, is with some moving-parts switching to reverse a winding > direction (the commutator on a DC generator reverses the winding polarity); so > an AC motor/DC generator or other 'rotary converter'. That doesn't rely on the > dB/dt to be always-increasing, it changes the orientation of the 'area' and flips the sign > in the dot product so that the product is never negative.https://en.wikipedia.org/wiki/Magnetic_detector NT
Reply by ●November 5, 20152015-11-05
On Wed, 4 Nov 2015 23:29:59 -0800 (PST), Bill Beaty <billb@eskimo.com> wrote:>On Tuesday, November 3, 2015 at 10:03:19 AM UTC-8, Piotr Wyderski wrote: >> You don't need to challenge me, I have exactly the same >> experience after nontrivial amount of googling. There's >> nothing about it. > >I recall seeing (about 10yrs ago) a ref to math showing that it's not possible; that even the ideal case, mag amp operating point is outside the gain/phase for oscillation. I didn't look up the ref though. > >It was in an article on historical development of electronics, claiming that the first oscillators had to wait for vacuum tubes, since even though mag amps existed earlier, oscillators weren't possible. (But even Faraday coulda made one, if he had Nyle Steiner's burned zinc oscillator.)Pre-tube, big radio transmitters, hundreds of KW things, used negative-resistance arcs to make true oscillators. Not to be confused with spark gap transmitters, that just made ringing oscillations. https://en.wikipedia.org/wiki/Arc_converter -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●November 5, 20152015-11-05
John Larkin wrote:> On Wed, 04 Nov 2015 08:49:10 -0800, Robert Baer > <robertbaer@localnet.com> wrote: > >> John Larkin wrote: >>> On Tue, 3 Nov 2015 16:19:34 +0100, Piotr Wyderski >>> <peter.pan@neverland.mil> wrote: >>> >>>> John Larkin wrote: >>>> >>>>> If you mean a DC powered circuit that oscillates using only passive >>>>> parts and diodes, no relays or such, I've never seen it done. >>>> >>>> I'm not sure if you can call a magnetic amplifier a passive part. >>>> It can exhibit admirable power gain, but needs to be powered by AC, >>>> for example: >>>> >>>> http://sparkbangbuzz.com/mag-audio-amp/mag-audio-amp.htm >>>> >>>> The guy claims it has the gain of 2000. So recently, I have >>>> started to wonder if you can use such a device as a DC-powered >>>> oscillator. I agree, the answer "yes" would be a surprise, but >>>> maybe it is "yes" indeed? >>>> >>>> Best regards, Piotr >>> >>> You can also make an amplifier or an oscillator using varicap and >>> rectifier diodes, but it also needs an AC pump. >>> >>> Since nobody has done what you suggest in about 200 years of >>> tinkering, I suspect it can't be done. >>> >>> >>> >> And the bee cannot fly. > > Some things are actually impossible. > > Bees can obviously fly. What idiot decided that they can't? > > If you can design an oscillator that meets Piotr's requirements, we'd > love to see it. > >Am not so good at designing with nonlinear components. Know of the trick using nonlinear inductors in a discrete L,C PFN to get faster risetimes; not sure how helpful that maybe in this case. First i need to find nonlinear inductors/transformers that do not need excessive power to act that way. And the play with them. I do know that as the excitation is increased on the Ma Bell ring generator, that there is some point that it starts to become unstable, and finally (as an oscillator to run at 20Hz) settle down in the preferred mode; that info is not helpful. If you have other clues, please let me know.
Reply by ●November 5, 20152015-11-05
tabbypurr@gmail.com wrote:> On Thursday, 5 November 2015 21:08:03 UTC, whit3rd wrote: >> On Wednesday, November 4, 2015 at 11:30:05 PM UTC-8, Bill Beaty wrote: >> >>> Separate topic: is an all-inductors diode possible, using magnet-biased saturable reactors? I recall a Tesla patent claiming this. If real, why all the rotary converters, and why were selenium or copper-oxide rectifiers such a big deal? >> >> A rectifier, with an AC source, produces DC EMF; but any magnetic field >> that produces in a winding a DC EMF, must have >> >> d(flux)/dt ~= dotproduct( (area) ,dB/dt )>0 >> >> in a net average over time. That's a ramp in B that never every decreases: you can not >> do that, over any sufficiently long period of time the B field will exceed your magnetic >> material limits (or current supply capability, or material strength limits). >> >> The best you could do, is with some moving-parts switching to reverse a winding >> direction (the commutator on a DC generator reverses the winding polarity); so >> an AC motor/DC generator or other 'rotary converter'. That doesn't rely on the >> dB/dt to be always-increasing, it changes the orientation of the 'area' and flips the sign >> in the dot product so that the product is never negative. > > https://en.wikipedia.org/wiki/Magnetic_detector > > > NTHumph. "Maggie" was the term used in radar as a short term for the magnetron..
Reply by ●November 5, 20152015-11-05
On Thu, 05 Nov 2015 15:45:37 -0800, Robert Baer <robertbaer@localnet.com> wrote:>John Larkin wrote: >> On Wed, 04 Nov 2015 08:49:10 -0800, Robert Baer >> <robertbaer@localnet.com> wrote: >> >>> John Larkin wrote: >>>> On Tue, 3 Nov 2015 16:19:34 +0100, Piotr Wyderski >>>> <peter.pan@neverland.mil> wrote: >>>> >>>>> John Larkin wrote: >>>>> >>>>>> If you mean a DC powered circuit that oscillates using only passive >>>>>> parts and diodes, no relays or such, I've never seen it done. >>>>> >>>>> I'm not sure if you can call a magnetic amplifier a passive part. >>>>> It can exhibit admirable power gain, but needs to be powered by AC, >>>>> for example: >>>>> >>>>> http://sparkbangbuzz.com/mag-audio-amp/mag-audio-amp.htm >>>>> >>>>> The guy claims it has the gain of 2000. So recently, I have >>>>> started to wonder if you can use such a device as a DC-powered >>>>> oscillator. I agree, the answer "yes" would be a surprise, but >>>>> maybe it is "yes" indeed? >>>>> >>>>> Best regards, Piotr >>>> >>>> You can also make an amplifier or an oscillator using varicap and >>>> rectifier diodes, but it also needs an AC pump. >>>> >>>> Since nobody has done what you suggest in about 200 years of >>>> tinkering, I suspect it can't be done. >>>> >>>> >>>> >>> And the bee cannot fly. >> >> Some things are actually impossible. >> >> Bees can obviously fly. What idiot decided that they can't? >> >> If you can design an oscillator that meets Piotr's requirements, we'd >> love to see it. >> >> > Am not so good at designing with nonlinear components. > Know of the trick using nonlinear inductors in a discrete L,C PFN to >get faster risetimes; not sure how helpful that maybe in this case.Saturating magnetics can do cool high-power stuff that would destroy semiconductors. Like the nonlinear delay lines you mention. I've seen some biggish eximer lasers that used saturating magnetics to make the big pulse drives into the discharge tubes. Very rugged.> First i need to find nonlinear inductors/transformers that do not >need excessive power to act that way. > And the play with them. > I do know that as the excitation is increased on the Ma Bell ring >generator, that there is some point that it starts to become unstable, >and finally (as an oscillator to run at 20Hz) settle down in the >preferred mode; that info is not helpful.Do you mean the old central office ring generators? There is very little online about them, but they seemed to be rotating motor-generators mostly. The CO stuff did all ultimately run off 48 volts DC. Do you know of a non-rotating, non-semiconductor, DC powered ring generator? Bell was pretty good with magnetics. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●November 6, 20152015-11-06
On Thursday, November 5, 2015 at 2:21:25 PM UTC-8, John Larkin wrote:> > Pre-tube, big radio transmitters, hundreds of KW things, used > negative-resistance arcs to make true oscillators. > > Not to be confused with spark gap transmitters, that just made ringing > oscillations.Even after tubes were available, the spark-gap oscillator was a standby of diathermy/induction heating. Crude, effective, and in a welding shop you need to ventilate against other gas buildup, so why not against ozone?
