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Author Topic: Investigating "anomalies" in Bifilar coils  (Read 155512 times)
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I can't seem to get a COP that is NOT "overunity" from this thing. Setting FG to 15 v p-p and 1.00 MHz I get:

IN
4.00 x 0.0329 x cos -74.58 = 0.03499 W

OUT
1.462/51 = 0.04179 W

COP 1.19

 :D
   

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But the diagram indicates...
I don't see any sensing of the current delivered by the AC voltage source to the entire circuit ( including L1 ).  Wouldn't that be prudent?
Multiplying this input current by the AC voltage of the source would yield the true power delivered by this AC voltage source.

IN:
Math "average" computed by scope is 1.60 mW. 
Do you mean the average of the Math channel AVG(Ch1*Ch2) ?   I did not see that on the scopeshot...
   
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I don't see any sensing of the current delivered by the AC voltage source to the entire circuit ( including L1 ).  Wouldn't that be prudent?
Multiplying this input current by the AC voltage of the source would yield the true power delivered by this AC voltage source.

You'll have to ask Partzman about that. I'm just following his circuit diagram and probe connection points.

Quote
Do you mean the average of the Math channel AVG(Ch1*Ch2) ?   I did not see that on the scopeshot...

It's easy to miss, especially since I didn't post the scopeshot itself for those first two trials. But see below for where it appears in other scopeshots. Red ovals indicate where the Math average shows up, Green ovals indicate the "raw" data used for the manual calculations:



   
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S'matter? Is everybody's anomalometer pegged out?  :o
   

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TK,

No need to wind a special coil although you are welcome to do that.  I was hoping you or TM could try you existing TBC's with my schematic layout.  The operating frequencies should be lower and it will be interesting to see the results.

The ground connections are correct as you show.  I have a coax cable from the signal generator (set at 50 ohm impedance) which connects to a BNC male and then short leads for all connections.  I am not using a probe and clip on the 1 ohm sense resistor but rather I remove the probe and use just the inner probe tip and a supplied Tek spring contact placed on the ground sleeve.  This probe connects directly across the TO-220 packaged sense resistor.

I looked at the data sheet for the Ohmite resistors and with an inductance <1nH @1MHz, they should be fine.  The 50 ohm load resistor should also be non-inductive as you know.

The output current measured in the sense resistor is the same as the input current drawn from the generator source.  This can be confirmed with a current probe placed in the input line to the transformer assembly.  KCL also demands they be the same unless there is an outside source of energy or current entering the circuit which in this case there is none.

The negative phase angle is due to my specifying that the phase measurement be taken from CH1 to CH2.  If I had stated CH2 to CH1, the angle would be positive but in either case, the current leads the input voltage.  This is a result of the fact that when the primary is driven at one end while the other end is open, the generator sees a reactive load due to the distributed capacitance between the primary and secondary.  The resulting displacement currents create induction in the loaded secondary.

Edit: OOps, I see I missed your last question on the wiring.  No, this is not connected in the standard Tesla manner.  The two windings are separated electrically and the dots indicate the start of the windings or the inner connections.  So, the generator connects to the start of L1 with the other end left open.  The start of L2 then connects to the top of the load resistor R1 with the finish connecting to the junction of R1 and R2.  If these connections are reversed, the operating characteristics will be completely different!

Pm

I'll give it a go PM,but my scope(or maybe me using the scope)is not so good for calculating power when phase angles and power factor have to be taken into account.

Also,is not the schematic missing something?--see modified schematic below.
Would this bring any light as to why TK is see all this OU ?.
Looks to me like a current loop,when the missing parts are added.

I did try the !one end of the coil disconnected! thing some time back,and indeed could get a good voltage across a 100 ohm resistor,and light up LED,from the two ends of L2.


Brad


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Here my measurement ( at 1.4MHz) on a Bifilar Pancake coil (no solonoid like TK used).

I used my current probe to measure / calculate the input green current, (current controller at 100mA/Div.) yellow is FG voltage.
So input power is 256mW, see screenshot 1


Output power measured to be 187mW using the math and the blue / purple traces, see screenshot 2.

When i calculate the output power like TK did CH3 (purple) Vrms² / 51,   i get (3.274² / 52 (in my case) = 206mW


Food for thought.

Regards Itsu
   
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Hi Itsu,

Sorry to chime in, did you measure the load resistance to be 52 Ohm? 

(and in your formula you first wrote 51 Ohm and then calculated with 52 Ohm,  with 51 Ohm the output power would be 210.2 mW)

Gyula
   
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TK and TM,

I'm curious to see if your Tesla bifilar coils will produce a COP>1 when following the attached schematic if either of you or anyone else has the time.  The coil polarity is important and a 50 or 100 ohm load could be used.  Select a 1 ohm for current sensing that is non-inductive and 1% in tolerance if possible.  When connected as shown, find the resonant frequency and then take measurements at a frequency that is 60-66% of the resonance frequency.

The test coil used below is a 33 turn bifilar wound with 2-28awg ribbon cable on a form that has dimensions based on the golden mean ratio.  I have not had success with round coils for this type of induction.  A difference in the windings (apart from lower inductance and capacitance) is these are side by side where yours are planar.

The scope pix BPT_1 shows the basic measurements which reflect an input power of 29.33mw and an output power of 1.493^2/51 = 43.7mw for a COP = 1.49.  These measurements were taken with a 64 sample average and a record length of 1e6 points. 

Pix PBT_2,3 allow one to check the pin accuracy against the measured phase angle between CH1 (input voltage) and CH2 (output/input current).

Pm

Have you tried pulsed DC with this setup to see if sharp transients produce more pronounced COP>1 results?

THanks,

Dave
   

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Have you tried pulsed DC with this setup to see if sharp transients produce more pronounced COP>1 results?

THanks,

Dave

I have tried a square wave,and can dissipate a lot more power from R2.
But,now i have a saw tooth wave form across the input CVR--is the RMS value of a sawtooth wave form still used to calculate P/in ?.


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Here my measurement ( at 1.4MHz) on a Bifilar Pancake coil (no solonoid like TK used).

I used my current probe to measure / calculate the input green current, (current controller at 100mA/Div.) yellow is FG voltage.
So input power is 256mW, see screenshot 1


Output power measured to be 187mW using the math and the blue / purple traces, see screenshot 2.

When i calculate the output power like TK did CH3 (purple) Vrms² / 51,   i get (3.274² / 52 (in my case) = 206mW


Food for thought.

Regards Itsu

I think you don't have enough phase shift. Try tuning the frequency until you get around -75 to -85 degrees of phase shift between input voltage (yellow) and input current (green).
   

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author=TinselKoala link=topic=3445.msg61395#msg61395 date=1493623631]

Quote
I can't seem to get a COP that is NOT "overunity"

I seem to be having the same problem.

Looking at scope shot 3-named P/in,even if we disregard power factor correction,and assume that the apparent power is the real power value,i am still dissipating more power from the 100R,than the calculated P/in--and the 1R has not even been taken into consideration yet.

So apparent P/in is 3.84V @ 37.6mA= an apparent power of 142.88mW
If the power factor is less than 1,would not the real P/in be less than 142.88mW ?

Power dissipated by the 100R is 3.84VRMS - 35.2mV= 3.8048VRMS
3.8048 across 100R=144.765mW
Plus 35.2mV across 1 ohm =1.24mW

Total P/out (resistors only),is 146mW

COP=102.2
This is without power dissipated by the two coils.

I would suspect the COP would go up once power factor correction is done--but how would you go about correcting the power factor with an open coil?

This was just a random frequency also,and only selected because it gave the greatest amplitude across the 100R


Brad




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Also,is not the schematic missing something?--see modified schematic below.
I would think so.
Also the CSR (R2) will not "catch" the current flowing through those capacitances you've added.  This allows some of the input energy to appear at the output without being accounted for.

To fix this measurement error, sensing of the current delivered by the AC voltage source to the entire circuit ( including L1 ) should be added.
   

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I would think so.
Also the CSR (R2) will not "catch" the current flowing through those capacitances you've added.  This allows some of the input energy to appear at the output without being accounted for.

To fix this measurement error the sensing of the current delivered by the AC voltage source to the entire circuit ( including L1 ) should be added.

How can that be,as all the input energy must go through the 1 ohm R2.

The input loop must include R2 for the path to be complete,as the capacitance only accounts for 1 leg of the input.


Brad


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How can that be,as all the input energy must go through the 1 ohm R2.
The current flowing from the AC voltage source to L1 is not "caught" by R2 because L1 forms a capacitance with the ground (including the free end).
   

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The current flowing from the AC voltage source to L1 is not "caught" by R2 because L1 forms a capacitance with the ground (including the free end).

The ground is in series with R2,and so the input current must flow through R2-it has no other path.
If we disconnect the ground of the FG(the power source),the circuit will cease to function.


Brad



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Wow, what a flurry of activity on the BPT while I slept!  I'll try to answer all the questions after I get the sleep out of my eyes.

Pm
   
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Well, I suppose we need to hear from Partzman on that.


Meanwhile, back at the ranch....

I connected one of my TBF coils. Well, it's no longer a TBF, it is now a PBF I guess.

10 v p-p from FG, tuned frequency to produce a phase shift CH1>Ch2 of -80.51 degrees, which occurred at 422 kHz. This time I used the "PVrms" or period V rms values from the Measurements.

IN:
Math trace automatic average 8.17 mW
3.12 x 0.0158 x cos -80.51 = 0.0081277 W or 8.13 mW

OUT:
0.7952/50.58 = 0.012496 W or 12.5 mW

COP 1.54 

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I can't seem to get a COP that is NOT "overunity" from this thing. Setting FG to 15 v p-p and 1.00 MHz I get:

IN
4.00 x 0.0329 x cos -74.58 = 0.03499 W

OUT
1.462/51 = 0.04179 W

COP 1.19

TK,


OK, I'm pleased to see you measure OU with this setup but I'm hoping that your load resistor is not inductive enough to be affecting the results.  Otherwise everything looks good except that you are seeing OU over such a wide range of frequencies.  However, you are using a round coil arrangement with a lot of turns and I would be curious if you have an estimate or know how many turns and what gauge wire?

Thanks for taking the time and effort to run these tests.

Pm

 :D
« Last Edit: 2017-05-01, 15:04:29 by partzman »
   

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The current flowing from the AC voltage source to L1 is not "caught" by R2 because L1 forms a capacitance with the ground (including the free end).

L1 forms a capacitance with L2,and L2 is in series with R2 and the ground.


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The ground is in series with R2...
"Ground" is a point. It cannot be in series with anything...anymore that it can be in parallel with anything.
Only multi-terminal components can be connected in series or parallel.

L1 forms a capacitance with L2....
L1 forms a capacitance with much more than L2.  This bypasses R2.  Also, for input power calculations, the input voltage should not include the voltage drop of R2.
Designate the other side of R2 as the "ground" point and see for yourself
   
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Partzman, the solenoid coil is #33 green enamelled magnet wire, 376 turns (188+188) wound on a wooden dowel 12.67 mm diameter. I have not accounted for the DC resistance of the coil halves which is about 5.10 ohms per half.
   
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I don't see any sensing of the current delivered by the AC voltage source to the entire circuit ( including L1 ).  Wouldn't that be prudent?
Multiplying this input current by the AC voltage of the source would yield the true power delivered by this AC voltage source.

Do you mean the average of the Math channel AVG(Ch1*Ch2) ?   I did not see that on the scopeshot...

Yes that would be prudent but not necessary with one caveat and that is, we assume there is no feed forward induction from the generating source to the device that would bypass the intended wiring paths.  In the beginning I used a current probe in the AC voltage source line to confirm this wasn't happening as the probe measurement agreed with the sense resister in magnitude and phase.  So, the circuit will then follow KCL in thqt the current in the sense resister placed as shown will represent the input current from the AC source.

PM
   
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I'll give it a go PM,but my scope(or maybe me using the scope)is not so good for calculating power when phase angles and power factor have to be taken into account.

Also,is not the schematic missing something?--see modified schematic below.
Would this bring any light as to why TK is see all this OU ?.
Looks to me like a current loop,when the missing parts are added.

I did try the !one end of the coil disconnected! thing some time back,and indeed could get a good voltage across a 100 ohm resistor,and light up LED,from the two ends of L2.


Brad

Brad,

OK, great. 

I am not understanding where you see a ground loop (not to say there isn't one) so could you perhaps be a little more specific.  Otherwise the equivalent circuit is as you show.

Pm
   
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Here my measurement ( at 1.4MHz) on a Bifilar Pancake coil (no solonoid like TK used).

I used my current probe to measure / calculate the input green current, (current controller at 100mA/Div.) yellow is FG voltage.
So input power is 256mW, see screenshot 1


Output power measured to be 187mW using the math and the blue / purple traces, see screenshot 2.

When i calculate the output power like TK did CH3 (purple) Vrms² / 51,   i get (3.274² / 52 (in my case) = 206mW


Food for thought.

Regards Itsu

Itsu,

There appears to be something wrong with the current to input voltage phase in your scope pix for some reason.  The current should be leading the input voltage by ~80 degrees or so and yours appears to be considerably less than that.  Compare your results with TK's post #97 for example.  What are the specs on your coil assembly like the inductance of each winding, inductance of the windings in series, and the capacitance between the windings?

Thanks for doing the test.

Pm
   
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Have you tried pulsed DC with this setup to see if sharp transients produce more pronounced COP>1 results?

THanks,

Dave

Dave,

Yes I have tried using pulsed sources to drive the device directly and my experience has shown it to be less effective compared to a sine source.   However, one may use an inductor in series to resonate with the distributed capacitance of the device while using a pulse as the source and the result will be much larger signal and power levels.

Pm   
   
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