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From: legg <legg@nospam.magma.ca>
Newsgroups: sci.electronics.design
Subject: Re: switchmode gyrator
Date: Thu, 14 Nov 2024 08:19:23 -0500
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On Wed, 13 Nov 2024 07:41:44 -0800, john larkin <JL@gct.com> wrote:

>On Wed, 13 Nov 2024 09:32:56 +0000, liz@poppyrecords.invalid.invalid
>(Liz Tuddenham) wrote:
>
>>john larkin <jl@glen--canyon.com> wrote:
>>
>>> On Tue, 12 Nov 2024 19:44:39 +0100, Jeroen Belleman
>>> <jeroen@nospam.please> wrote:
>>> 
>>> >On 11/12/24 16:49, john larkin wrote:
>>> >> On Tue, 12 Nov 2024 07:49:13 -0500, legg <legg@nospam.magma.ca> wrote:
>>> >> 
>>> >>> On Sat, 09 Nov 2024 06:08:40 -0800, john larkin <JL@gct.com> wrote:
>>> >>>
>>> >>>>
>>> >>>>
>>> >>>> Inductors are awful. Their energy storage is worse than electrolytic
>>> >>>> caps by about a factor of 1000.
>>> >>>>
>>> >>>>
>>> >>>>https://electronics.stackexchange.com/questions/326177/energy-density-
>>> >>>>comparison-between-inductors-and-capacitors
>>> >>>>
>>> >>>> One could in theory make a switchmode gyrator that would make a
>>> >>>> capacitor look like a programmable-value inductor.
>>> >>>>
>>> >>>> I have an application for that, but it would take too much engineering
>>> >>>> and runtime complexity to make it worth doing. I guess I'll just have
>>> >>>> to buy a bunch of giant, heavy custom toroids.
>>> >>>
>>> >>> I'm sure that there are other reasons why an inductor
>>> >>> will be used besides the lack of time/energy/resources
>>> >>> to 'design them out'.
>>> >>>
>>> >>> Energy storage is just one means to an end.
>>> >>>
>>> >>> RL
>>> >> 
>>> >> Sure. We want to design some dummy loads that will simulate relays,
>>> >> solenoids, stepper motors, torque motors, with programmable R and L.
>>> >> Seemed to me that using caps to make fake inductors would be a good
>>> >> way to do that.
>>> >> 
>>> >> It's at least an interesting idea to play with. Maybe we can
>>> >> switchmode simulate R+L all at once. We would have to store energy and
>>> >> dissipate power to do that.
>>> >
>>> >Relays and motors do not behave like simple inductors. For example,
>>> >while a relay armature is moving, the back EMF is high enough to
>>> >make the current _drop_ briefly. Modelling that requires more than
>>> >a simple gyrator.
>>> >
>>> >Jeroen Belleman
>>> 
>>> My customer is building giant rackmount boxes full of heavy inductors
>>> as part of his dummy loads. We want to replace them.
>>
>>If space, weight and stray magnetic fields aren't a problem, big
>>inductors can sometimes turn out to be remarkably cheap and efficient
>>compared with more complex solutions.
>
>We have learned that our customers care a great deal about rack space
>and cables. And they used to have techs that built things like load
>boxes, and when those old guys retired they didn't replace them.
>
Then be carefull, because you're dealing with the wankers who are 
 still hanging around with their fingers . . . .

>We may make some smaller R+L dummy loads by switching real resistors
>and tapped inductors. That is brain straining, especially specifying
>the tapped inductors.
>
>I was musing on designing a switchmode programmable synthetic R+L box
>with essentially infinite programmable resolution, and using caps for
>the energy storage instead of real inductors.
>
>I suppose there can be a generalized impedance simulator.