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Author Topic: Adiabatics, subresonance, and eliminating resistance  (Read 259 times)
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Hi All,

I'm bored this afternoon, and thought maybe I'd get some thinking going on the general subject of reducing thermal losses in all electronic circuits. I deliberately leave out any superconductors or the like.
I've seen a number of approaches to this in the literature:

1) most commonly, using resonance to raise the voltage and reduce the current in a circuit-- resonance being an approximation to:
2) using adiabatic (ramp voltage) supplies and loads, as done in some experimental computers
3) using a T-network that creates a negative resistance, inductance or capacitance on one of the legs of the T, as used in filter circuits, developed by Tellegen and Bode
4) using a negative feedback amplifier and a hybrid circuit to feed back an inverted form of thermal noise, reducing it, as in Harold Black, and Robert Forward's gravitational detectors
5) using HF waves along a single wire, as in Tesla's experiments
6) using circuit elements made of thermoelectric materials, as in the Dotto Ring


Of course, this is a very heterogenous group of technologies, all that might reduce the thermal losses, or thermal noise, in a circuit composed of at least an R.

I think perhaps the most elegant, and simplest to apply, is the use of subharmonics. It turns out that resonance is not the most efficient state. This is implied by the fact that a ramp voltage is more efficient than a quarter sine voltage in the adiabatic computers. The paper by Boehler and Snider I recently uploaded has an interesting experiment. Just to make a point about whether charge memories had a future in nano tech, they show how the thermal losses due to the resistance in an RC (or presumably an RL) circuit are reduced, as the drive F is reduced relative to the resonant F. 

We can start with any arbitrary R, and a time T we need energy to pass through this resistance. We then add a C (or L?) to this R, such that the time constant T1 of the resulting RC circuit is much shorter than the transfer time we need. Resistive losses in the circuit are reduced by T/T1. The practical limit is that systems already containing capacitance (or inductance?) have a built in 'time limit'. But when it comes to pure resistance you want to get rid of, just add your reactance, and drive at lower frequency than the RC.

Other methods seem to be a more sophisticated way of doing the same thing. Tellegen, the inventor of the gyrator, shows in an interesting patent that one can create a negative resistance along one leg of a T- or Star- connection, that cancels almost all of the R of that leg for one frequency. This was later used by Bode for improving frequency selection in filters. But the method seems to have much wider application than that. For instance, an arbitrary resonant circuit could have one of these passive filter type circuits imposed along its path, and the Q would be dramatically increased, substantially as if the circuit R would be dissolved.
 
Everything I'm saying is simply a reframing of well known and conventional physics, embodying the idea that "if you do things slower, you don't waste as much energy". But the principle does have wide application in electronics outside of adiabatic computers, where it has been stuck for decades.
A first use of such an invention would be the ramp charging of storage supercapacitors, and I've seen just a tiny interest in applying the idea in that area.

The other methods are generally stranger physics. I think the most interesting of these is the techniques first discussed by Harold Black and later used by Forward in the detection circuits for his huge gravitational detectors. Black used a negative feedback amplifier with a gain of 1, fed back through a hybrid transformer to cancel all the electron noise in the circuit. He reports that the circuit lost heat when it was working. I'm not sure why this technology isn't being used in High end audio equipment.

The rest I just put on there to see how many I could think of :-)

Regards,
Fred




   

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Buy me some coffee
It is the magnetic field around the conductor that causes resistance.

Neutralize that field,and you remove the resistance of the conductor.


Brad


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The current in a superconductor does create a magnetic field, yet there is no resistance.
The magnetic field is the corollary of the movement of charges, the two are one and the same physical reality, not related to the resistance.


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"Chance favours only the prepared mind."  Louis Pasteur
   

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Buy me some coffee
The current in a superconductor does create a magnetic field, yet there is no resistance.
The magnetic field is the corollary of the movement of charges, the two are one and the same physical reality, not related to the resistance.

A super conductor has to have it's magnetic field produced before it is bought down to a super conductive state.So if it is already in a superconductive state,it will reject any magnetic field trying to induce it. This is why a PM will float above a super conductor.

The magnetic spin of the field built around a current carrying conductor apposes the flow of the electrons being pushed through the wire by the source. This can be better understood when looking at the homopolar generators back torque when a load is placed on the output.

If you look at the video below,you will see that where the magnetic field around the conductive wire is neutralised by the counter turns magnetic field,the wire dose not melt like the rest of the length of wire. This means that it is dissipating less heat. The only way this can happen when the value of current flowing through the length of wire is the same at every point, is if the resistive value of that length of wire is lower than the rest of the length of wire.

https://www.youtube.com/watch?v=ZuJjy9wj9vU&feature=youtu.be

We can visualize this by looking at the effect of dropping a neo magnet down through a copper pipe. If we see the magnet as an electron,and the pipe representing the conductor,which produces a magnetic field around that electron,then we can clearly see the resistance to flow the electron encounters by the induced magnetic field around the pipe.


Brad


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Never let your schooling get in the way of your education.
   
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Tinman,

F6LT is correct. You can easily eliminate the action (not the existence) of the magnetic field on the current, in a well constructed noninductive coil. It still has resistance.
 
There was a reason I deliberately left superconductivity off my subject list here. Superconductivity takes energy to create. In this thread, I'm looking at room temperature electronic effects that can reduce heat dissipation in circuits. There are two purposes, raising the efficiency, and reducing the heat load on the atmosphere (although F6LT has pointed out that human heat is a small contributor to global warming, why not reduce it anyway?).
Many of these methods are covered in the field called Finite Time Thermodynamics, which considers how to make processes least entropic given a limited time for a process to happen.

Although, for instance, the adiabatic computing is well understood, it is not well understood how general these principles are, and how broadly they can be applied.

The attached paper on Finite time thermodynamics uses the example of heating a coffee cup by moving it to different rooms, each a little warmer than the next, shows that our normal methods of creating heat are entropic.
Simply put, when we turn on the heat in our room, heat generation starts at the maximal level (ie full current in the elements of the heater). The heat then spreads throughout the heater and then the room, and the temperature gradually rises to our desired comfort.
However, this process is equivalent in many ways to charging a capacitor by applying full voltage right away. As you probably know, if the voltage is controlled to a ramp, so that the charging v is always just a little higher than the v on the capacitor, the process is much more efficient because the current is reduced. 
The paper implies, not in so many words, that if we heat a room the same way, so that the temperature of the heating element is always just some proportion warmer than the surrounding room, then the process of heating will occur with much less entropy creation.
So in practical terms, we would establish a time that we are willing to endure being cold, and then establish a temperature differential between the heater and the room such that the temperature in the room meets our requirements in that time. The heater senses the room temperature and always keeps its temperature above it by the required proportion. The creation of the desired warm room consumes less electrical power by controlling the heat production in this way.
I've seen no commercial application of this science, but it certainly seems possible to create energy saving appliances that apply it.

Regards,
Fred
   

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Might be interesting article about step-charging capacitor to minimize entropy


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Hi Vasik041,

"Charging A Capacitor" adds to the article you posted.

F.
   
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