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Author Topic: Investigating "anomalies" in Bifilar coils  (Read 157055 times)
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It's turtles all the way down
I wonder what one has to do or where one has to be at the right time to find a benefactor that would bless one with such equipment?


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Russ is a man of faith [devout Christian] he is also fervently open source.

perhaps his benefactor is of like mind ?
   

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Russ is exploring here also [Thx to Matt Watts]

https://www.youtube.com/watch?v=-HDwOwfIHns

Unfortunately Russ got it wrong  C.C

He says in the video,that he is measuring the voltage across two resistors,which are the two traces on the scope.

If he is doing this,then power factor plays no part in the calculated power dissipated by those two resistors.

Russ says ohms law dose not apply here,but he is wrong. The power dissipated by the two resistors is always calculated using ohms law,regardless of the phase shift between V & I-power factor.

I often wonder how those not so blessed in the art,are those who end up with so much support  ???


Brad

P.S
I feel a response video coming on.


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It's turtles all the way down
I agree, the video was rather inconclusive, more just like a fleeting overview on power factor without addressing the meat of your question.  ???

I'm truly glad that Russ is fervently open source. Hopefully his benefactor feels that way too.  :)

Where could I find a benefactor?........ :)


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I agree, the video was rather inconclusive, more just like a fleeting overview on power factor without addressing the meat of your question.  ???

I'm truly glad that Russ is fervently open source. Hopefully his benefactor feels that way too.  :)

Where could I find a benefactor?........ :)

Indeed.

Here in Australia,it would be 10 times as hard to find such a benefactor.


Brad


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So,if the voltage and current wave forms are in phase,then all P/in is being dissipated by the load?,as we would see across a pure resistive load.

So,if i can get the current and voltage wave forms in phase on(what is) R2 and L2 in the BPC,then all power is being dissipated by the R and L ?.


Brad


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Below are the scope shots with associated scope placings as requested by TK,with the widened time scale.
I have also included the math trace for each,which is showing the result of V x I.


Brad


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Ok.... it would still be better if your scope could compute the phase shift itself. But in your First shot, if we take the rms current through R1 (CH2) as 0.0618V/10R = 0.0062 Arms as the current being supplied to the system, and the voltage drop across the whole circuit (CH1), and estimate the phase shift as 72 degrees, we then calculate the total input average power as
P = Vrms x Irms x cos (72 degrees)
P = 6.60 x 0.0062 x 0.309
P = 0.0126 W or 12.6 mW

And if we calculate the power dissipated in R1 as
P = Vrms2/R
P = 0.0712/10
P = 0.0005 W

And the power dissipated in R2 as
P = Vrms2/R
P = 0.3482/10
P = 0.0121 W

So we get the total power dissipated in the resistors as
0.0005 + 0.0121 = 0.0126 W or 12.6 mW.

Coincidence?

This result is very sensitive to the Phase Shift in part 1, so we really need a good measurement of that.
   

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Ok.... it would still be better if your scope could compute the phase shift itself. But in your First shot, if we take the rms current through R1 (CH2) as 0.0618V/10R = 0.0062 Arms as the current being supplied to the system, and the voltage drop across the whole circuit (CH1), and estimate the phase shift as 72 degrees, we then calculate the total input average power as
P = Vrms x Irms x cos (72 degrees)
P = 6.60 x 0.0062 x 0.309
P = 0.0126 W or 12.6 mW

And if we calculate the power dissipated in R1 as
P = Vrms2/R
P = 0.0712/10
P = 0.0005 W

And the power dissipated in R2 as
P = Vrms2/R
P = 0.3482/10
P = 0.0121 W

So we get the total power dissipated in the resistors as
0.0005 + 0.0121 = 0.0126 W or 12.6 mW.

Coincidence?



This would indicate that we have two ideal coils.
But we know that cant be correct,as they both have resistance,and there is current flowing through them,and any current that flows through a resistance creates heat,and that is dissipated power.

Quote
This result is very sensitive to the Phase Shift in part 1, so we really need a good measurement of that.

Well thats the best i can do,with the el'cheapo scope i have.

There is also a second problem i have found,regarding that increase in current you spotted in scope shot 1 and two,where only the channel A's probe was moved to the end of L1.
Seems my scope may be shagged,as i tried this out with other circuit's,and when ever i move 1 probe to a different location(while the ground leads remain together),the voltage value in the other channel rises or fall-such as in scope shots 1 and 2 above.

I tried another set of probe's from my dad's old scope,and the same thing.
Also did a self cal on the scope,and no better.
So looks like the scope is done/fried,and a new one is not within the budget ATM-or for some time for that matter.

I have a feeling that running the scope off of my inverter,and the FG from main's,has done something to the scope,when the two grounds(SG and scope)were put together,while the phases from the mains and inverter would not have been in sync. I did notice a lot of wobble in the wave forms ,when using the inverter to run my scope. The inverter is a pure sine wave inverter,and i checked it with my scope-very clean sine wave,with 242VRMS.

Maybe i join the church,and get what Russ has got  O0 lol.


Brad


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...any current that flows through a resistance creates heat,and that is dissipated power.
Yes, and current is always in phase with voltage in an ideal resistor, so power factor is not applicable to calculating power dissipated by such resistors.

However, power dissipated in input resistors is not the same as input power....even if all of the electric input energy is delivered through these resistors.  See MPTT.
If a load is purely resistive then the power dissipated in that resistance is the same as output power - but that is a special case.
   
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Brad, can you confirm that your FG "black" output lead is not grounded back through the chassis and to the mains ground pin?

Also, my estimate of 72 degrees phase shift is just that: an estimate based on the scope's graticule markings, the trace zero crossings and peaks.  Also, your coil has relatively few turns of pretty heavy wire I think, so your coil's DC resistance is probably very small. Can you get a reading of that somehow? A  more careful estimate of the phase shift, and including the coil's DC resistance, may make some difference in the calculations.


I'm not sure how the Max Power Transfer Theorem affects these calculations or conclusions, except that the true Input Power is likely to be larger than what we are calling Input Power. Maybe Verpies can help out here. Really, what we are calling Input power should actually be considered the total power dissipation of the load circuit, and I think my calculations breaking down the power dissipations of the various parts of the circuit show that this is correct. So we are really back to square one, since we don't actually know the impedance of the power source (the FGs we are using). I'd like to believe that my ElCheepo DDS is 50 ohms impedance but I don't think it actually is.
   

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Yes, and current is always in phase with voltage in an ideal resistor, so power factor is not applicable to calculating power dissipated by such resistors.

However, power dissipated in input resistors is not the same as input power....even if all of the electric input energy is delivered through these resistors.  See MPTT.
If a load is purely resistive then the power dissipated in that resistance is the same as output power - but that is a special case.

Yes,i am aware of that.
It dose however,give you the input current.


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Brad, can you confirm that your FG "black" output lead is not grounded back through the chassis and to the mains ground pin?

Also, my estimate of 72 degrees phase shift is just that: an estimate based on the scope's graticule markings, the trace zero crossings and peaks.  Also, your coil has relatively few turns of pretty heavy wire I think, so your coil's DC resistance is probably very small. Can you get a reading of that somehow? A  more careful estimate of the phase shift, and including the coil's DC resistance, may make some difference in the calculations.


. Maybe Verpies can help out here. Really, what we are calling Input power should actually be considered the total power dissipation of the load circuit, and I think my calculations breaking down the power dissipations of the various parts of the circuit show that this is correct.

Quote
Brad, can you confirm that your FG "black" output lead is not grounded back through the chassis and to the mains ground pin?

TK
I have always stated that my FGs black lead is grounded,and so is the scopes ground lead's.
This is why i have to use my inverter to run my scope,so as i get isolation between the two common ground's of the scope and FG.

Quote
So we are really back to square one, since we don't actually know the impedance of the power source (the FGs we are using). I'd like to believe that my ElCheepo DDS is 50 ohms impedance but I don't think it actually is.

With my FG,you can either choose 0 or 50 ohms impedance.

Quote
I'm not sure how the Max Power Transfer Theorem affects these calculations or conclusions, except that the true Input Power is likely to be larger than what we are calling Input Power

Unless the power factor is 1,then i think the real power value will be less than the apparent power we are measuring.

I carried out a load test today,using a simple load.
The load is a FWBR,with a cap across the output of the FWBR,and an LED as a load(also across the cap)

With the FG placed on the AC input of the FWBR,i can get 2.82 volts across the cap/LED-BPC circuit not in play.
This is the maximum power the FG can deliver to the load(LED)

If i then hook the FG leads to the BPC circuit,minus the input resistor R1(R2 still in play-10 ohms),and then place the AC inputs of the FWBR at a certain turn of L2,and the other at the input of L1,i can get 2.91 volts across the cap/LED,and 700mV across R2

Not only is the dissipated power greater in the LED,when the BPC is in play,we are also dissipating 49mW of power from R2. But this is only when one side of the FWBR is on a certain turn of L2--i think it was the 3rd or 4th turn in from the outer turn.
If i go a turn either side of the correct one,then the power being delivered to the load drop's to a value below that of what the FG it self could deliver to the load.

Thought that was interesting.
Will shoot a video tomorrow after work,and post here.


Brad


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TK
I have always stated that my FGs black lead is grounded,and so is the scopes ground lead's.
This is why i have to use my inverter to run my scope,so as i get isolation between the two common ground's of the scope and FG.

With my FG,you can either choose 0 or 50 ohms impedance.

Unless the power factor is 1,then i think the real power value will be less than the apparent power we are measuring.

I carried out a load test today,using a simple load.
The load is a FWBR,with a cap across the output of the FWBR,and an LED as a load(also across the cap)

With the FG placed on the AC input of the FWBR,i can get 2.82 volts across the cap/LED-BPC circuit not in play.
This is the maximum power the FG can deliver to the load(LED)


If i then hook the FG leads to the BPC circuit,minus the input resistor R1(R2 still in play-10 ohms),and then place the AC inputs of the FWBR at a certain turn of L2,and the other at the input of L1,i can get 2.91 volts across the cap/LED,and 700mV across R2

Not only is the dissipated power greater in the LED,when the BPC is in play,we are also dissipating 49mW of power from R2. But this is only when one side of the FWBR is on a certain turn of L2--i think it was the 3rd or 4th turn in from the outer turn.
If i go a turn either side of the correct one,then the power being delivered to the load drop's to a value below that of what the FG it self could deliver to the load.

Thought that was interesting.
Will shoot a video tomorrow after work,and post here.


Brad

Can you provide more data for the above statement?  What impedance did you have your FG set to for this test as well as how you measured the effective impedance of the load?  If you don't have these two nailed down, you might not be within the max power transfer capabilities of the circuit.  By adding the BPC, you might be bringing the network closer to the proper impedance match for max power transfer.

Dave
« Last Edit: 2017-04-30, 15:14:30 by web000x »
   

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It dose however,give you the input current.
Yup

The load is a FWBR,with a cap across the output of the FWBR,and an LED as a load(also across the cap)
Such load will draw current only when the input voltage is higher than the voltage across the cap + voltage drop of the FWBR.
As such the i(V) relationship will not be linear and the current waveform will not be sinusoidal.

The cos(φ) power factor cannot be used to adjust power calculations for non-sinusoidal waveforms.
   
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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
   
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Partzman, I don't have the right kind of dual-strand wire to make a coil like yours for testing. I do have precision 1 ohm 1 percent non-inductive current sense resistors (also have 0.1 ohm) Ohmite WN series type.

I took the liberty of making explicit the ground connections in your circuit diagram; I hope this is a correct reflection of how you had things connected in your tests. Please let me know. As you know, even a few inches of wire in probe or other ground connections can have enough inductance to throw off results.

I am also not sure that measuring input and output current through the same resistor at the same time is a legitimate measurement, and I am somewhat troubled by the negative phase angle. Does this negative angle mean that you are testing at a frequency that is higher than the resonant frequency of the coil?

I am also trying to wrap my head around the wiring connections of your coil. Let's see... starting at the outside "top" terminal, winding around to inside top, connected straight from there to outside bottom, winding around from there to inside bottom terminal, do I have that right? But the diagram indicates that the connection from inside top to outside bottom is left open, right? So this isn't really connected as a Tesla Bifilar coil, is it?



   
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Partzman, I don't have the right kind of dual-strand wire to make a coil like yours for testing. I do have precision 1 ohm 1 percent non-inductive current sense resistors (also have 0.1 ohm) Ohmite WN series type.

I took the liberty of making explicit the ground connections in your circuit diagram; I hope this is a correct reflection of how you had things connected in your tests. Please let me know. As you know, even a few inches of wire in probe or other ground connections can have enough inductance to throw off results.

I am also not sure that measuring input and output current through the same resistor at the same time is a legitimate measurement, and I am somewhat troubled by the negative phase angle. Does this negative angle mean that you are testing at a frequency that is higher than the resonant frequency of the coil?

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 
   
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OK, thanks, time for meditation. 

(Of course there is only a single current in R2. I am troubled still by counting it as both input and output simultaneously, I guess.)
   
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Heh....   :D

OK, I hooked up the Partzman circuit above to my bifilar _solenoid_ coil and here are the results from two trials at 1.433 MHz. I just connected the scope probes to the test points using their normal spring-hooks. I didn't have a 50R noninductive resistor though so I just used 2 metal-film 100R in parallel. The 1R is an Ohmite precision noninductive.

Trial 1:
Data:
CH1 Vrms = 1.25 V
CH2 Vrms = 0.0144 V
CH3 Vrms = 0.66458
phase 1-2 = -82.76 deg

IN:
Math "average" computed by scope is 1.60 mW.  Calculating from CH1 and CH2 traces p-p converted to RMS and phase shift I get
1.25 x 0.0144 x (cos -82.76 deg) = 0.00227 W or 2.27 mW

OUT:
0.664582 / 51 = 0.00866 W or 8.66 mW

COP = 3.81

Trial 2:
Data:
CH1 Vrms = 1.24 V
CH2 Vrms = 0.01456 V
CH3 Vrms = 0.6610 V
phase 1-2 = -80.69 deg

IN:
Math "average" computed by scope is 3.90 mW. Calculating from CH1 and CH2 traces p-p converted to RMS and phase shift I get
1.24 x 0.01456 x cos (-80.69 deg) = 0.00292 W or 2.92 mW

OUT:
0.66102 / 51 = 0.008567 W or 8.57 mW

COP = 2.93


I can haz cheezburger now?
   
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A representative scopeshot (Trial 3) and the data dump for that shot:

   
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.... and the calculations for that shot (#3):

IN:
CH1rms x CH2rms x (cos phaseshift) =
1.21 x 0.0139 x (cos -78.17) = 0.0032956 W or 3.30 mW

OUT:
CH3rms2/R =
0.5822/51 = 0.0066416 W or 6.64 mW

COP = 2.01
   
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Trial #4 at 928 kHz:

IN:
1.38 x 0.011 x (cos -81.33) = 0.0022883 W or 2.29 mW

OUT:
0.4972/51 = 0.0048433 W or 4.84 mW

COP = 2.11




Isn't anyone besides me awake at this hour?   8)


   
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Trial #5 at 462 kHz:

IN 0.0005588 W or 559 uW
OUT 0.001398 W or 1398 uW or 1.40 mW
COP 2.50
(manual setting of scope channels vertical and horizontal and position parameters)

IN 0.0008276 W or 828 uW
OUT 0.001398 W or 1398 uW or 1.40 mW
COP 1.69
(using scope's AutoSet function to automagically set vert, horiz and position parameters)



   
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OK, last one. Doubling FG voltage setting to 10v p-p at random frequency of 912 kHz:

IN
2.74 x 0.0211 x cos -79.85 = 0.01019 W or 10.2 mW

OUT
0.8832/51 = 0.01529 W or 15.3 mW

COP 1.50

   
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