I found a North American mains power distribution diagram that I am posting here since everybody is concerned about grounds.

Note there is a kind of "uneasy" relationship between the third-prong ground and the neutral line.  The thing to remember about the neutral line is that there still can be considerable voltage on it because multiple neutrals may have a considerable amount of current flowing through them.

For Conrad, I think that you used the term "mains-ground" for what your scope and signal generator BNC grounds were connected to.  I will assume that that is equivalent to what myself and TK have been calling the third-prong ground.  I note that the types of home power plugs and socket systems used in various European countries are safer and superior to what we have in North America.

TK you mentioned lifting the third prong to isolate the signal generator.  Call it superstition, but I still get "queasy" because of the "uneasy" relationship between the third-prong ground and the neutral line.  With a lot of activity on a given breaker circuit I wonder if a signal generator with a cut third-prong might still "flutter" in potential a bit.  I am no expert here but you know the whole big deal with milking cows and "tingle voltage?"

TK, another thing to mention is going back to the scope and the input amps.  You schematic was incomplete but I don't need to see it.   Again, just consider this:  The inputs sense voltage relative to the BNC ground, which we know is normally connected to the third-prong ground.  The input amplifiers of the scope have to be powered by some kind of DC voltage that is relative to the BNC ground.  However, the main guts of the scope are powered by neutral-hot.  Therefore, there must be an isolation transformer inside the scope that goes from [neutral - hot] to [BNC ground - (DC power supply out)] to power the input amps.  Does that make sense?

MileHigh

@MH: Yes of course it makes sense and it is obvious how that isolation/connection happens when you look at the complete schematic for the scope's power supplies. You can easily look them up yourself so I won't post another image.

The connection between the "Ground prong" and the line neutral _inside the house wiring_ is exactly why you do NOT want the "ground" connected to line neutral inside the instrument! Or the instrument's line neutral connected to the chassis. You pointed out the dangers of this in an earlier post, and the house wiring diagram should make it clear. The Ground wire connects to the line neutral at the distribution panel inside the house. If there is a wiring glitch, somebody mistakenly connected White and Black wires wrong to an outlet ... (White is neutral, Black is Death, instead of the electronics convention where Black is usually Ground....) well, you can imagine what can happen.


the "flutter" from lifting the ground prong is why I suggested that the FG be lifted, not the scope. The scope is a precision measuring instrument and is sensitive to bad stuff on the supply line, whereas the FG is a DC-instrument, modern ones are logic-controlled, and will be less sensitive, I think, to input voltage "flutter". If you want to see true nonsense on a supply line, look at the output of a cheap inverter or UPS some time... true sinusoidal output inverters and uninterruptible power supplies are rare and expensive.

Sure. Solas are great but kind of expensive and I don't have one to hand any more. Used to, when I was in Canada, but not now.

http://www.ebay.com/sch/i.html?_nkw=sola%20isolation%20transformer&clk_rvr_id=773187970953&adpos=1s7&MT_ID=70&crlp=22617129323_2416792&device=c&geo_id=10232&keyword=sola+isolation+transformer&crdt=0

But believe it or not, some of these things actually do _not_ isolate the Ground pin -- it goes straight through from the isolated side to the mains side, to assure equipment grounding!

Sure. Solas are great but kind of expensive and I don't have one to hand any more. Used to, when I was in Canada, but not now.

http://www.ebay.com/sch/i.html?_nkw=sola%20isolation%20transformer&clk_rvr_id=773187970953&adpos=1s7&MT_ID=70&crlp=22617129323_2416792&device=c&geo_id=10232&keyword=sola+isolation+transformer&crdt=0

But believe it or not, some of these things actually do _not_ isolate the Ground pin -- it goes straight through from the isolated side to the mains side, to assure equipment grounding!

Those all look huge and are very expensive.

Plan B:  Go to an electronics surplus place and buy pairs of very cheap matched transformers.   Connect them [front-back-back-front] and you have a perfectly good isolation transformer.  I bet you could make one for less than twenty bucks.

The word "resonance" has crept in.  That's new?

Cool, the YouTube guy that repairs old radios sometimes shows a variometer coil inside a radio.  I think more often in 1920s radios.

I view "resonance" for this project as a blind alley.  We all know how abused and misapproproated that term is.  The question for Chris is "Why?"

My personal update on Smudge's research:  He is now talking about "negative resistance effects between two coaxial coils spaced a certain distance apart on a ferrite bar" giving you over unity.  He has done some modelling and even looked up propagation velocities inside the ferrite bar.  It looks like he is talking about magnetic field propagation velocities.  I am not sure if he is also looking into fine-grained magnetic domain flipping propagation velocities.  He suggests it could be over unity but worries about other losses drowning out the alleged over unity effects.

Well, then please do a timing diagram Smudge.  Put your money where your mouth is and turn all of your research into a comprehensive timing diagram.  Show where the over unity manifests itself on the timing diagram.  You can even model various elements as being ideal so that the alleged over unity shows up.  I know that my comments are being worded as almost a challenge as opposed to a request.  There is a reason for that though.  How often have we seen claims of over unity and when you ask the claimant for a timing diagram explaining what they are discussing they give you strange looks.  I figure after all the talking, you either sink or you swim based on your capability to make a credible timing diagram that shows your alleged over unity process.

MileHigh

Conrad:

Okay, we are going to review the business about moving the resistor from the ground line to the AC-output line of the function generator.  You posting is quoted below and I also attached your marked-up graphic.

I did not discuss this earlier because it was not that important at the time and I did not want to interrupt your process.  Now is the time to talk about it and the reason goes back to the fundamental principles of getting a proper understanding of what is going on and also not to lead ourselves down a garden path.  These are very important principles.

Your statement:

<<<<<<
While doing the "reality check" suggested by MileHigh  (output only from one of the partnered coils)  I realised that I had a bad error in the measurement set up.

Please look at the attached drawing. The error is caused by the ground connection between my scope and my function generator.

The shunt R1 (on the input side in series with the primary coil) is in a bad place, because it lifts the potential of the primary off the ground. This would not be any trouble unless one measures the output with a scope, which has a ground connection to the mains ground and then to the ground of the function generator. The secondary is pulled down to ground and the output looks smaller that it is.

The error is not very big, the output was about halved. But because the output is so much lower than the input, this is no great thing.

I will redo the measurements with the shunt R1 in the right place (on the signal side, not at the ground side of the primary).
>>>>>>>

There is actually nothing wrong with your original configuration with R1 on the bottom connected to the ground line.  So let's examine this and find out why.

You say, "The shunt R1 (on the input side in series with the primary coil) is in a bad place, because it lifts the potential of the primary off the ground. This would not be any trouble unless one measures the output with a scope, which has a ground connection to the mains ground and then to the ground of the function generator. The secondary is pulled down to ground and the output looks smaller that it is."

You say, "It lifts the potential of the primary off the ground."  Let's say it more precisely:  When the resistor is on the ground line, the bottom of the coil gets an "AC wobble" and the top of the coil is fixed and must follow the AC voltage from the function generator.

Let's examine when the resistor is on top.   Then we can say when the resistor is on the function generator output line, the top of the coil gets an "AC wobble" on top of the regular AC signal and the bottom of the coil is fixed and must follow the ground potential.

So the main difference is that in one case the "AC wobble" is on the bottom of the coil, and in the other case the "AC wobble" is on the top of the coil.  As far as the coil itself is concerned, it makes no real difference.

You say, "This would not be any trouble unless one measures the output with a scope, which has a ground connection to the mains ground and then to the ground of the function generator. The secondary is pulled down to ground and the output looks smaller that it is."  This is related to the red text in your diagram where you say, "therefore the secondary is also offset from ground."

Here is the issue:  If there is a "AC wobble" on the bottom of the primary coil because the resistor is on the ground line, this in theory will not directly affect the potential difference you can measure across the secondary coil.  The secondary is completely floating and separate from the primary.  For example, there is no real potential difference that you can measure between the bottom of the primary and the bottom of H3 because there is no electrical connection between the two entities.  When I say this I am intentionally ignoring any possible capacitive coupling effects.

You say, "the output was about halved."  I believe you and I am not challenging your observation.  However, there is no direct link between your observation and moving the resistor from the bottom to the top.  A secondary effect may have caused this.  For example, when you made the ground connection with your cable clip lead to the secondary, the ground shield loading from the entire length of your scope cable may have attenuated your voltage measurement on the secondary.  The setup on the secondary is "weird" with the resistor between two fighting coils and the whole thing may have been high-impedance and "extra sensitive."  You know sometimes when you touch a signal that you are scoping with your fingertip and you see the signal go down in amplitude by 90%?  Perhaps something like that.   My proposed modified setup in posting #712 may work and mitigate those issues because the recommendation is to either not even use the ground clip leads of your scope cables, or to leave them connected at the central ground point.

But, to bring it all back home.  From what I see at least on paper, there was nothing wrong with having the R1 resistor on the bottom on the ground line.  In theory all of the measurements can be made with no problems with ground loops, etc.

MileHigh