PopularFX
Home Help Search Login Register
Welcome,Guest. Please login or register.
2017-11-18, 15:49:24
News: Forum TIP:
The SHOUT BOX deletes messages after 3 hours. It is NOT meant to have lengthy conversations in. Use the Chat feature instead.

Pages: 1 2 3 [4] 5 6
Author Topic: Magnetic CARA - Proof of Concept  (Read 22750 times)

Hero Member
*****

Posts: 1219
What was the current probe amplifier set to during the last 6 scopeshots posted or what was the peak current flowing through R1 or L1 lead?

See screenshot 1,  blue is A to C, yellow A to B, green is the current probe at the csr.  Hard to trigger, no current seen.
probe ground clips to point A?
   

Hero Member
*****

Posts: 1154

Finally for tonight,  this is the same setup as above, but with 40uF C1(yellow no current through the csr, green current through L1 (10mA/Div.))

Regards Itsu
   

Hero Member
*****

Posts: 1154
What was the current probe amplifier set to during the last 6 scopeshots posted or what was the peak current flowing through R1 or L1 lead?

Through L1   10mA/Div. as on the scope,  when at R1 position 50mA/Div. as i have high noise level there (because of the ground leads of the scope there near by?)


Quote
probe ground clips to point A?


Yes.


Itsu
   

Hero Member
*****

Posts: 1219
The inverted C2 waveform begins to resemble the waveform from this simulation which illustrates how that circuit is supposed to work.
Notice how the current through L1 rises slowly and falls quickly in the sim.  
When the current falls, the energy stored in L1 is quickly transferred to C2 and as a consequence of this, C2 is charged up to 162V.
The smaller the C2, the faster the transfer...unfortunately the penalty for higher speed is higher voltage and parasitic oscillations.

Click me - you must have Java enabled to run this sim

BTW: 100m means 100mΩ which is the same as 0.1Ω

« Last Edit: 2015-02-27, 01:07:46 by verpies »
   

Hero Member
*****

Posts: 1154
Very nice,

i tried to mimic the wave forms from your simulation and came up with the below screenshot.
I had to manipulate some channels, like setting the blue channel from inverting (as it should be) to normal, but then its close.

Yellow is across the csr (allmost no signal)  A-B
blue is voltage across C2 + csr  A-C
green is current through L1 (top) set at 20mA/Div. B-L1

Regards Itsu
   

Hero Member
*****

Posts: 1219
Very nice, I tried to mimic the wave forms from your simulation and came up with the below screenshot.
I hope you did not waste too much time analyzing the driving/control circuit.  
It is not important - all it does is pulses the coil for 2ms, then waits for 3ms and shorts C2 for 1ms (optionally recharging C1 from the PS).

I had to manipulate some channels, like setting the blue channel from inverting (as it should be) to normal
Yes, that was a good move.

If you click on the "Click Me" switch to periodically disconnect from the power supply and observe the voltage across C1 then you will notice, that its voltage falls to approximately half (from 30V to 15V) during the L1's rising current ramp.
This decrease in voltage across C1 represents the input energy to this circuit very accurately according to the simple formula E=½CV2.
If you compare the energy lost by C1 to the energy gained by C2, then you will obtain the energy recovery efficiency of this circuit.  A very important number.

Yellow is across the csr (allmost no signal)
Green is current through L1 (top) set at 20mA/Div.
That surprises me.  The real world magnitudes should be within 10% of the simulated magnitudes.
The simulation shows 502mAP-P flowing through L1 but your current probe shows only 41mAP-P, so there seems to be a ~ 10:1 error somewhere.
Also, with 500mA flowing through R1 there should be a 50mV signal across R1 - that should be clearly visible (at least 2 divisions!).

Most importantly, why is the difference between the length of the rising and falling current ramp, so large in the sim but so small in the real world ?


« Last Edit: 2015-02-15, 15:56:24 by verpies »
   

Hero Member
*****

Posts: 1154

I cannot explain this 1:10 difference,  also my C2 voltage raises to 47V max., so nowhere near your 162V

Video of the setup and scope sequence here:  https://www.youtube.com/watch?v=IXh-jiQN6zM&feature=youtu.be


Regards Itsu
   

Hero Member
*****

Posts: 1154
When inserting a 0.5mm plastic spacer between the core halfs, then things start to look more like the sim, see screenshot 1
L1 measures 75mH in that situation.

Yellow is across the csr  A-B
blue is voltage across C2 + csr  A-C
green is current through L1 (top) set at 200mA/Div. B-L1

When removing again the top core half, then we get the screenshot 2 situation    (L1 = 11mH)     Current controller set to 1A/Div.


Itsu
   

Hero Member
*****

Posts: 1219
I cannot explain this 1:10 difference,
And when you calibrate your current probe with a known DC (e.g. from your DC power supply across a power resistor) then the reading is correct ?
Perhaps your scope misconfigures the Ch4 which you are using for this purpose, because you are using a raw BNC cable from your current probe amplifier, without any autosense signals present on it.
   

Hero Member
*****

Posts: 1154

Right,  i did that,  a 224.2 Ohm resistor on 13.23V (0.059A) measured by the probe to be 58mA, so it looks to be OK.


Itsu
   

Hero Member
*****

Posts: 1154
I know we are not really ready for this next step, but i wanted to let some viewers see what the idea is behind this setup if they did not already know that.

I used 2 x 2 ceramic magnet stacks with similar poles (so not like i mentioned in the video opposing poles) to let both pot cores halfs being repelled.
They are being held together at a distance of 2mm by some tape.

The inductance measured is 21mH @ 2mm away to 32mH when pushed together (there is a piece of plastic inside the pot core to prevent again from cracking up the halfs).

Presently the halfs will not be pulled together when C1 is loaded only, only when the PS is left on, there is enough power to click both halfs together.

See this video for a rough idea:    https://www.youtube.com/watch?v=COTJ6Ngmpq8&feature=youtu.be
Regards Itsu

   

Hero Member
*****

Posts: 1219
Right,  i did that,  a 224.2 Ohm resistor on 13.23V (0.059A) measured by the probe to be 58mA, so it looks to be OK.
So unless that current measurement is wrong only for non-DC, we have to assume that it is correct.

Let's see where that takes us.
Because inductance L=V/(di/dt) then we can calculate the inductance of L1 from the slope of the current trace on these scopeshots.

We pay attention only to the starting slope of the curve, because later on, other phenomena can come into play, such as core saturation, V/R limit and L1C1 oscillation if S0 is open.

When removing again the top core half, then we get ...  (L1 = 11mH)     Current controller set to 1A/Div.


L=V/(di/dt)  ==> 30V / (5.2A / 2ms) = 11mH
Also, you can see the current trace beginning to curve down before Q1 turns off, due to L1C1 oscillation happening because S0 is opened - this means that Q1 is closed too long for this inductance.

When inserting a 0.5mm plastic spacer between the core halves, then things start to look more like the sim, see screenshot 1
L1 measures 75mH in that situation.

Green is current through L1 (top) set at 200mA/Div.


L=V/(di/dt)  ==> 30V / (800mA / 2ms) = 75mH



L=V/(di/dt)  ==> 30V / (46mA / 2ms) = 1304mH      WTF?!!!  :o
Was the supply voltage correct in the calculation above (or... if S0 was opened, then was C1 charged to 30V when Q1 closed ) ?

Also, we can see that when the current reaches 35mA then it starts to curve up (goes above the orange helper line), which is indicative of core saturation.



« Last Edit: 2015-02-16, 11:54:35 by verpies »
   

Hero Member
*****

Posts: 1219
I know we are not really ready for this next step, but i wanted to let some viewers see what the idea is behind this setup if they did not already know that.
Yes, we are not ready to deal with the dynamic mode with the movement of the core.  We don't even know what the recovery efficiency of our circuit is in the static mode.  Also our L1 charging period should be at least 5x longer than its discharge period and we are not even in the neighborhood of that yet.

When operating with S0 open, please also monitor the voltage across C1  so you can compare how much it decreases vs. how much the voltage across C2 increases after 1 recovery.  Dividing these two energies, calculated according to E=½CV2, will tell us the recovery efficiency.

I used 2 x 2 ceramic magnet stacks with similar poles (so not like i mentioned in the video opposing poles) to let both pot cores halves being repelled.
They are being held together at a distance of 2mm by some tape.
It pretty clever to use the magnetic field as a spring, but such technique will have side effects such as saturating the core material.
To harness the mechanical movement/vibration of the core, a magnet with a second coil will have to be used - most likely ...or a piezo.
Also the moving mass should be minimized - not maximized.

Presently the halfs will not be pulled together when C1 is loaded only,
only when the PS is left on, there is enough power to click both halves together.
When the PS is left on (S0 closed) what pulse width do you use, to energize the coil?
   

Hero Member
*****

Posts: 1154

So unless that current measurement is wrong only for non-DC, we have to assume that it is correct.

I did some earlier CSR/current probe comparisons for ac waves which panned out to be OK to, see:
http://www.overunityresearch.com/index.php?topic=2751.msg45747#msg45747

Quote
Let's see where that takes us.
Because inductance L=V/(di/dt) then we can calculate the inductance of L1 from the slope of the current trace on these scopeshots.

We pay attention only to the starting slope of the curve, because later on, other phenomena can come into play, such as core saturation, V/R limit and L1C1 oscillation if S0 is open.

L=V/(di/dt)  ==> 30V / (5.2A / 2ms) = 11mH

Also, you can see the current trace beginning to curve down before Q1 turns off, due to L1C1 oscillation happening because S0 is opened - this means that Q1 is closed too long for this inductance.

L=V/(di/dt)  ==> 30V / (800mA / 2ms) = 75mH

Your calculated inductance's (11 and 75mH) are spot on with my LCR meter measurements here:
http://www.overunityresearch.com/index.php?topic=2751.msg46030#msg46030

Another prove that the current probe is working fine.

Quote
L=V/(di/dt)  ==> 30V / (46mA / 2ms) = 1304mH      WTF?!!!  :o
Was the supply voltage correct in the calculation above (or... if S0 was opened, then was C1 charged to 30V when Q1 closed ) ?

Also, we can see that when the current reaches 35mA then it starts to curve up (goes above the orange helper line), which is indicative of core saturation.

Yes supply voltage was 30V as all the rest of the tests.
I try to follow this sequence, discharge C2, then charge C1 via S0, then apply the pulse.
We had this problem before with both pot core halfs together, only when introducing a gap between the halfs or removing the top half
things seem to get normal, like here:
http://www.overunityresearch.com/index.php?topic=2751.msg45834#msg45834


Regards Itsu
   

Hero Member
*****

Posts: 1154
Yes, we are not ready to deal with the dynamic mode with the movement of the core.  We don't even know what the recovery efficiency of our circuit is in the static mode.  Also our L1 charging period should be at least 5x longer than its discharge period and we are not even in the neighborhood of that yet.

When operating with S0 open, please also monitor the voltage across C1  so you can compare how much it decreases vs. how much the voltage across C2 increases after 1 recovery.  Dividing these two energies, calculated according to E=½CV2, will tell us the recovery efficiency.

Well the problem with that is as mentioned earlier, that when leaving the DMM across C1, it will discharge within 10 seconds.
That was with the 1.8uF C1 at least the case.


Quote
It pretty clever to use the magnetic field as a spring, but such technique will have side effects such as saturating the core material.
To harness the mechanical movement/vibration of the core, a magnet with a second coil will have to be used - most likely ...or a piezo.
Also the moving mass should be minimized - not maximized.
When the PS is left on (S0 closed) what pulse width do you use, to energize the coil?

I had to go back to 100Hz (10ms) on the FG, so a 5ms pulse.

Regards Itsu
   
Hero Member
*****

Posts: 529
@ITSU

I think the reason your cores are not clacking together is your top and bottom magnets are in repulsion so your pulsed coil would have to neutralize one of the polarities and produce an opposing polarity on that same side for it to then make the cores clack. That will not happen and that is why you see no effect. What you are trying to do is very tricky.

I would do it with magnets in attraction, that would keep the cores together and the pulse would only need to create one same polarity on either top of bottom to spread the core.  Also two magnets per side may be too much.

Or the simplest way is to suspend the complete coil from the top and let gravity do the work and the pulse will bring the cores halves together. But at least if suspended, any pulse reaction will be better seen then if it is lying on the table.

wattsup



---------------------------
   

Hero Member
*****

Posts: 1219
I did some earlier CSR/current probe comparisons for ac waves which panned out to be OK to, see:
http://www.overunityresearch.com/index.php?topic=2751.msg45747#msg45747

Your calculated inductance's (11 and 75mH) are spot on with my LCR meter measurements here:
http://www.overunityresearch.com/index.php?topic=2751.msg46030#msg46030

Another proof that the current probe is working fine.
Yes, I agree.
...but we still have this huge error that cannot be ignored.
Your meter says 110mH and your scopeshot says 1304mH.

Let's measure the inductance by a 3rd method.
Solder a 100nF capacitor rated 100V (or 200v) in parallel with the coil, while both potcore halves are clamped together and manually connect a 300mV power supply to it for 0.5sec, while scoping the ring-down voltage across the cap.  
You don't need to pulse it with the MOSFET, just briefly touch the Cap & Coil combo out of our circuit, manually with your power supply wires (0.3V) and observe the ring-down frequency on the scope.  (the "Normal" triggering mode will nicely freeze it on the display ;) )

It would be prudent to measure the capacitance of that 100nF cap as a sanity check, too.
   

Hero Member
*****

Posts: 1219
I think the reason your cores are not clacking together...
I think they "clack" with longer pulse widths.
It's just that Itsu does not like them to "clack" too much because he had an accident while doing so.

Or the simplest way is to suspend the complete coil from the top and let gravity do the work and the pulse will bring the cores halves together.
That's what Grumage was designing in the 1st post of this thread.
In the final stages of this experiment we will want the cores to move but we want to finish discharging L1 into C2 before they "Clack".
   

Hero Member
*****

Posts: 1154
@ITSU

I think the reason your cores are not clacking together is your top and bottom magnets are in repulsion so your pulsed coil would have to neutralize one of the polarities and produce an opposing polarity on that same side for it to then make the cores clack. That will not happen and that is why you see no effect. What you are trying to do is very tricky.

Hi Wattsup,      but they do clack together, see the very end of the above video, it only takes some juice (30V/10A PS connected for 5ms).

Quote
I would do it with magnets in attraction, that would keep the cores together and the pulse would only need to create one same polarity on either top of bottom to spread the core.  Also two magnets per side may be too much.

1 magnet per side was to weak (no repulsion), 3 to much. 

Quote
Or the simplest way is to suspend the complete coil from the top and let gravity do the work and the pulse will bring the cores halves together. But at least if suspended, any pulse reaction will be better seen then if it is lying on the table.

wattsup

Right,  there are severall ways to do this, like mentioned by verpies, we will look to that lateron,  but thanks.

Regards Itsu

   

Hero Member
*****

Posts: 1154
Yes, I agree.
...but we still have this huge error that cannot be ignored.
Your meter says 110mH and your scopeshot says 1304mH.

Let's measure the inductance by a 3rd method.
Solder a 100nF capacitor rated 100V (or 200v) in parallel with the coil, while both potcore halves are clamped together and manually connect a 300mV power supply to it for 0.5sec, while scoping the ring-down voltage across the cap.  
You don't need to pulse it with the MOSFET, just briefly touch the Cap & Coil combo out of our circuit, manually with your power supply wires (0.3V) and observe the ring-down frequency on the scope.  (the "Normal" triggering mode will nicely freeze it on the display ;) )

It would be prudent to measure the capacitance of that 100nF cap as a sanity check, too.


Mystery solved, it turned out that there was some debris on the flanges of the bobbin which was probably ever so slightly pushing against the ferrite top half causing it to lift very little while measuring the inductance (110mH).

After cleaning both the Bobbin and the pot core half's, and when pushing the top half down firmly while measuring, the reading now is 1250mH (depending on how hard is pushed).
So probably during the pulse the half's got pushed together tightly, overcoming the debris on the flange showing the inductance which you calculated from the screenshot (1300mH).

So we had a varying inductance all along  ;D

Regards itsu  

 
 
   

Hero Member
*****

Posts: 1219
So probably during the pulse the half's got pushed together tightly, overcoming the debris on the flange showing the inductance which you calculated from the screenshot (1300mH).

So we had a varying inductance all along  ;D
So now it's clear.  Good job!

Notice how tricky it is - let's suppose that this principle is essential for functioning of some OU device.
It works only if some some Russian vodka after-snack is stuck in the core, while for others less fortunate - it does not work...and we have a geo-dependency :D
   

Hero Member
*****

Posts: 1154


 :)    right,     very tricky, a cats whisker (and i have a lot of those around) can make a change from 1300mH to 240mH when caught inbetween the halfs.

Itsu
   

Hero Member
*****

Posts: 1154
Yes, we are not ready to deal with the dynamic mode with the movement of the core.  We don't even know what the recovery efficiency of our circuit is in the static mode.  Also our L1 charging period should be at least 5x longer than its discharge period and we are not even in the neighborhood of that yet.

When operating with S0 open, please also monitor the voltage across C1  so you can compare how much it decreases vs. how much the voltage across C2 increases after 1 recovery.  Dividing these two energies, calculated according to E=½CV2, will tell us the recovery efficiency.

It pretty clever to use the magnetic field as a spring, but such technique will have side effects such as saturating the core material.
To harness the mechanical movement/vibration of the core, a magnet with a second coil will have to be used - most likely ...or a piezo.
Also the moving mass should be minimized - not maximized.

When the PS is left on (S0 closed) what pulse width do you use, to energize the coil?

See the screenshot of the DMM's (yellow across C1, blue across C2) directly after the pulse was fired.

C1 was measured 39.82uF
C2 was measured 1.154uF

Video here: https://www.youtube.com/watch?v=7-zVKCi50gg&feature=youtu.be

Regards Itsu

   

Hero Member
*****

Posts: 1219
See the screenshot of the DMM's (yellow across C1, blue across C2) directly after the pulse was fired.

C1 was measured 39.82uF
C2 was measured 1.154uF

Video here: https://www.youtube.com/watch?v=7-zVKCi50gg&feature=youtu.be

Regards Itsu
DMMs and fingers are too slow :(
Would you like to automate S0 and S3 with relays driven from your SigGen?
Do you have 2 reed relays or other small relays ?

P.S.
That coil in the 1.4H state starts saturating at 30mA   :'(  dou you have another bobbin to wind it with a thicker wire?  This is not absolutely required...
   

Hero Member
*****

Posts: 1154
DMMs and fingers are too slow :(
Would you like to automate S0 and S3 with relays driven from your SigGen?
Do you have 2 reed relays or other small relays ?

P.S.
That coil in the 1.4H state starts saturating at 30mA   :'(  dou you have another bobbin to wind it with a thicker wire?  This is not absolutely required...

Ok,  yes, automated switches would be great.  No i don't have any, but i can order some,   reed relays, 5V, 12V?

I have another bobbin which i can put some thicker wire on, is  AWG 23 enough or thicker? (i now have AWG 28 on).

Itsu
   
Pages: 1 2 3 [4] 5 6
« previous next »


 

Home Help Search Login Register
Theme © PopularFX | Based on PFX Ideas! | Scripts from iScript4u 2017-11-18, 15:49:24