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Author Topic: Replication of ION's bifilar  (Read 96871 times)

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Meanwhile try some higher resistance chokes if you have them handy.

Thanks ION will do

Sounds like you are doing some interesting stuff above, cannot wait to join the party  ;)

I'm off until Tuesday now so away from my bench, i have almost caught up with all the work so hopefully get some time this coming week.

The strange thing was that when i first powered up for the first time the wires on the bifilar clonked together with force, and a couple of times after that on power up, but since i have adjusted the pot to give me the lowest frequency i have not seen this, it's as if either the cap or choke got fully charged up on power up by accident a couple of times.

Thanks for the help much appreciated.
   

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I remembered i had a MOT which i rewound the secondary for 320V and also added a filament winding for my valve pulsar, so i have just tried the primary and the 320V windings as my choke, still get very similar results, ticking but little increase in current.

I think i need some slightly thicker wire on the primary of my transformer, I am also going to lower the working frequency by increasing the 0.1 value.

If i turn the voltage down on my supply i can lower the frequency of operation by quiet a bit and there are a few spots, if i twang the bifilar i can start a small oscillation going, which seems to have a secondary wave rinding along the length.

Also placing a small neo magnet near the bifilar seems to change the noise from the driving circuit.

One other thing if i pull the bifilar apart i can see an increase in the amplitude of the scoped wave across the bifilar.
   
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Peterae:

I lowered my supply voltage to 125 volts and was not able to get much vibration. Also the bursts were not possible at this voltage with my setup. I tried larger discharge caps, up to 1.5 uf but pulse width does not seem to be the issue (area under the curve), rather it seems a steep HV pulse, very narrow seems to produce better results.

When the wires are hit with a fast rise, high current, short duration pulse, the effect is most prevalent. I have used up to 400 VDC, but I don't recommend you do that as I don't know if your SCR will handle the peak currents generated.

Perhaps the leakage inductance will help protect your SCR, as I see considerable ringing on your waveform, indicative of high leakage inductance in your matching transformer or a severe mismatch. I do not get this much ringing.

I have acquired a few new chokes to try. Will report in when I have something interesting.

I hope EM and WW join us on the bench, as theoretical analysis can only go so far until we learn more about this "kick" generation. Then we can expand the model.


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OK this makes sense, so it's possibly my low voltage supply.

I wondered what was causing the ringing, thanks for the explanation.
   

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Just a thought, what would be the result of placing a spark gap in series with the primary, Mark Snoswell used the SG method of sharpening his fet drive stage pulses, maybe this would speed the off time, the on time is great about 25nS with my Thyristor

Anyway i will be spending more time on my drive stage over the next couple of evenings to try and get up and running, i wish i had a variac  :-\
   
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Peterae,

Do you have a couple of transformers, a potentiometer and a 9V battery?  http://sparkbangbuzz.com/mag-amp/mag-amp.htm

This is an excellent replacement for a variac depending upon voltage and current requirements and what you have in your junk-box.
   

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I do indeed, that is a fabulous answer to my problems Thanks WW
   
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I do indeed, that is a fabulous answer to my problems Thanks WW

Make sure you follow the instructions on checking transformer compatibility  ;)
   

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Will do WW  O0

I went back to my 330nF C2 for now

I just wound a new transformer, i used quiet thick wire recovered from an old toroidal transformer, i wound 87 turns as bifilar and then series these for my primary giving me about 174 turns in total, i added about 7 turns of the same wire for my secondary.

The scope shot below is across my primary and secondary,

Green is primary 50V/div
Yellow is secondary 10V/div

Now if i am reading my secondary waveform correctly i have a 12V pulse across my bifilar which is 0.0817 Ohms
i make that 146 Amp pulse, yet my wire is jiggling i would say less than my previous setup.

I dont understand whats going on here, i just double checked both x10 swtiches were indeed flicked to x10 and they are.

At least i got rid of all that ringing.
« Last Edit: 2011-10-12, 22:26:44 by Peterae »
   
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very nice Peter,  I just noticed your work and the scope shots.   How far do the wires move when they kick?  is it a fraction of a mm? or slightly more?
   

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Hi EM it was too good to be true.

I went to bed finding it hard to believe i really had that much current through the bifilar, as it should have been twanging a lot more than my previous setup, so i knew something was wrong somewhere.

This morning i checked for a primary to secondary short and i had one, i unwound the secondary 7 turns and it looks like i wired it up with one of my primaries LOL, so it looks like i was running the secondary and bifilar in series with a primary winding DOH, I still couldn't work out how i had that much voltage across my bifilar though, but my 2 scope earths would have shorted something out as well, anyway i stopped trying to work it out, re connected my primary correctly and rewound my secondary and now i am back to where i started.

See scope shot below.Much more realistic

So i have about a 3.8V pulse into 0.0817 Ohms giving me a 46.5 Amp pulse that's better(or not as the case is  :( )

I find it strange that having a thicker primary wire and a lot more turns has not increased my secondary current much, i have also decreased my bifilar wire gauge to the same as the transformer i wire and i have swapped to a smaller ferrite ring than my first transformer.

So unless i am missing something then it looks like the only way is to run at higher voltage, time to look at building the mag amp dimmer.
   
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From Peterae:

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I find it strange that having a thicker primary wire and a lot more turns has not increased my secondary current much, i have also decreased my bifilar wire gauge to the same as the transformer i wire and i have swapped to a smaller ferrite ring than my first transformer.

Having more turns on the primary will lower the secondary voltage. It is a function of the turns ratio between primary and secondary that will determine the transformation ratio for voltage. The current is the inverse of this but only if the impedance is matched.

e.g lets say you have 100 turns primary and 10 turn secondary.  If the primary pulse is 100 volts at one amp, it will be transformed to ten volts secondary at 10 amps provided the load, in this case the bifilar has a low enough resistance to circulate 10 amps.

Now lets say you increase the primary to 200 turns while maintaining a ten turn secondary.  Now your transformation ratio is 20 to 1 so a 100 volt one amp primary pulse will deliver five volts at 20 amps to the secondary, again only if there is an impedance match to the bifilar load.

The primary wire is carrying much less current than the secondary. It is good that you were able to use a thicker wire for the primary. A good rule of thumb is to keep the DC resistance of both primary and secondary as low as possible to while maintaining the turns ratio required.

In efficient transformer design, we strive to keep the DC resistance of primary and secondary as low as possible while maintaining turns ratio required. Issues such as how much of what gauge will fit on a given core are engineering tradeoffs, and reflect a solution to a design problem also considering cost and allowable heating of the transformer, as well as power loss we can tolerate in the transformer.

For lab work and since we are not trying to shave production cost, we can err on the side of overkill and thus overdesign our transformer. In this way maximum energy is transferred through the transformer and we need not consider those losses which will be an order of magnitude lower than the rest of the circuit components.

Longwinded, but hope this helps.


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e.g lets say you have 100 turns primary and 10 turn secondary.  If the primary pulse is 100 volts at one amp, it will be transformed to ten volts secondary at 10 amps provided the load, in this case the bifilar has a low enough resistance to circulate 10 amps.

Now lets say you increase the primary to 200 turns while maintaining a ten turn secondary.  Now your transformation ratio is 20 to 1 so a 100 volt one amp primary pulse will deliver five volts at 20 amps to the secondary, again only if there is an impedance match to the bifilar load.

Thanks ION i knew that  :-[ as usuall i didn't think it through fool.

OK so this is good, all i need to do is measure my primary resistance like i did for the bifilar, back step my calculation to work out what voltage i need to run at to produce 100 Amps pulse on my secondary, i can then see if my thyristor is good as well.

I could also do it the hard way, if i plot my secondary loaded voltage against supply voltage i should be able to plot for the required 100Amps and obtain the psu voltage.

Again thankyou for tolerating a fool, your patience is much appreciated.

EDIT i am amazed at how efficient this driver circuit appears, i am only drawing between 1-2mA right now @ 125 V or 0.125W-0.25W
   
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From Peterae:

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OK so this is good, all i need to do is measure my primary resistance like i did for the bifilar, back step my calculation to work out what voltage i need to run at to produce 100 Amps pulse on my secondary, i can then see if my thyristor is good as well.

Don't be concerned with the primary resistance, just keep it as low as possible while respecting turns ratio.

Keep the secondary resistance as low as possible while also respecting turns ratio.

In other words, fill the core with as large a wire as it will hold, respecting turns ratio.

You can add taps to the primary to adjust the impedance match to the bifilar, this will give you an adjustable turns ratio stepped according to the taps thus allowing fine tuning of the system.


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I don't want to divert you guys from the current setup, lots to explore for sure,  but I think I'll implement a different approach to this experiment.   I like discharging a capacitor's energy directly into the wires, and I might just do that directly with an SCR and a very low ESR capacitor bank.  Than we can eliminate the transformer and not worry about the impedance matching issue.   But we must have a good SCR, get those nice big pucks for hundreds of amps!   O0
We might even explode wire!   >:-)
   

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Sounds Interesting EM, If you place your wire into a tube you will pretty silvered tubes  ;D

I would love to try a few things as well, it would be really great to trigger 2 scr's from my digital delay monos and i would like to try flat wire as well.

I just dug out a supply i had in the loft i had forgotten all about, it has 2 transformers back to back 240-25VAC and a 18V to 240VAC was giving over 400 V in it's original config, so just swapped it over to give 250VDC, looks like i am good to jiggle shortly  :)
   
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I don't want to divert you guys from the current setup, lots to explore for sure,  but I think I'll implement a different approach to this experiment.   I like discharging a capacitor's energy directly into the wires, and I might just do that directly with an SCR and a very low ESR capacitor bank.  Than we can eliminate the transformer and not worry about the impedance matching issue.   But we must have a good SCR, get those nice big pucks for hundreds of amps!   O0
We might even explode wire!   >:-)


Yes EM that is an alternate approach and valid. I've got quite a few of those large hockey puck SCR's and some of the mono block types.

I've refrained from using them, preferring to finesse the design rather than use the  heavy handed approach. You need to be sure of proper drive, risetime and hold current to the gate to be sure you get complete propagation and turn on of current across the wafer otherwise you will develop a hot spot and melt a hole through a portion of the wafer.

That's why I chose the Diac turn on technique. You can make the circuit work with just some resistance divider to the gate but this is hard on the SCR.

At least that's how it was in the early days of SCR drive, perhaps more modern devices do not have this issue.

Also you need a little ringing to allow the SCR to commutate off otherwise you will have to reset the system for every pulse. The matching transformer's leakage inductance does this nicely, although it can limit risetime.

If you choose to eliminate the matching transformer, you can experiment with gate turn-off techniques, such as the utilization of a small inductor gate to cathode. Or you can add a little inductance in the drive path to facilitate turn off.

Regardless of the approach I think you will be surprised when you hit the sweet spot of electro-acoustic resonance, which seems to occur at rather low PRR, in my setup between 100-200 PPS.

The wire excursions can be quite violent at that point and there seems to be some type of regenerative feedback from the wire. I have not explored this to my satisfaction, but it is worthy of further study. Perhaps it will verify your theory.


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i have now powered up using 250V supply, my bifilar is still not jiggling, strange really i would say the wires seem to be sticking together as if charged, maybe this is my imagination.

Anyway looks to me now i have a bit more current in my pulse, but there's a nasty kink to the bottom of the waveform, maybe core saturation?
Looks like i am briefly hitting 10V across my bifilar which is 122 Amps  8) just need to work out why there's little movement  :-\

Quote
in my setup between 100-200 PPS
I had not realized you were operating this high, i thought we were looking at 10's of Hz in that case i will try adjusting up from my current min setting.

EDIT crap when i start increasing the frequency the bifilar still doesn't jiggle but it gets dam hot real fast
maybe i need to start shortening the pulse width that area under the curve is currently 25-30uS
I am using copper rings at each end to anchor the bifilar down, it's just occurred to me these must be like 1 turn short circuit loops? could this be my problem maybe

you can see these rings in my photo post 13
http://www.overunityresearch.com/index.php?topic=1128.msg17469#msg17469
   
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My wires are stretched pretty tight, but do tend to loosen a bit if they heat up.

On my setup sweeping up from a low repetition rate, I hit the sweet spot but then this is hard to track and I loose it as the wire heats.

I'm beginning to think I need to zener regulate the diac supply at maybe 100 volts or less to provide some stability to the firing point. I also need a constant tension setup for the wires.

My HP power supply went south from some inductive kickback so I'll have to repair that. I recommend a brute force supply for some of these trials or use an isolation diode.

I don't think your rings are a problem, but you could try using plastic.

Try lowering your cap to .1 to .2 uF and try sweeping up from a very low rep rate. 10 to 100 Hz.

You may need some high value resistors to cut the rep rate down. Here's alternate circuit with wider adjustment range and zener regulation of the frequency control. I have not yet tested it
« Last Edit: 2011-10-13, 22:13:36 by ION »


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Cheers ION i will swap over my 0.1 for 0.2, i am still using a 330nF for C2 as well just checked and this is getting hot very fast as well, thyristor is cool.

My wires are stretched quiet tight as well, but do not seem to move much if at all, something not quiet right yet, i will try some more things tomorrow night.
   
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ION,   thank you for those insights on the need of the inductance for turn off.     The zenners you added are a great addition as well,  I always try to have some form of regulation when it comes to timing circuits so they don't drift with supply voltages changes. 

I just realized that I can use one of my blocking oscillators to create a nice stable series of spikes that is very short with a high dV/dt, and I think this will turn on the SCR quickly, so we don't have the problems you mentioned.   

Peterae,  you have all this current and the wires don't move that much?  Hmmm?  You might have a point about them sticking together,  I never thought of this, but if they are realy close,  what if the electrostatic attraction between the wires is slighlty larger then the magnetic repulsion?   I'll have to do some calculations  :-\

EM
   

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I have taken the copper rings off this morning, very little change really, if i sweep the pot i go from low audible ticking to what i would guess as a few hundred Hz, i will try to get some scope shots of this, but the result on the bifilar seems to be a fairly linear increase of repulsion across the length when running at the top end frequency, i can clearly see the bifilar start to separate from each other, i also realize i must be upping the overall dissipation in some of the components and soon start smelling overheating, although my C2 gets hot i think this maybe the pot, the thyristor runs cool, not sure about the diac yet.

I am still missing something, next i will try a smaller C2.
   
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Be forewarned any who attempt to build this circuit.

I have lost 3 power supplies that I have used over twenty years or more without a problem.

The circuit or something is generating an occasional large snap like a big capacitor discharge and takes out the power supply.

Even when I isolate the supply with diodes and an outboard cap, I have still had power supply failures.

I suggest anyone who wishes to experiment with this use a Variac, an isolation transformer and simple voltage doubler circuit to derive the 200 to 300 Volts DC required for it's operation. DO NOT USE YOUR GOOD SOLID STATE BENCH SUPPLY!!


I've got two repaired and one to go before I'm back on the bench, but I won't be using these supplies for this circuit.

Getting close to Halloween and this is spooky!

(P.S. anyone who can help me find a schematic for an ISS Enprotech 500 / 500 I will be very grateful)


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Muhuwaaaaaa!
Dudes! Remember my youtube vid where I grab the coil and snap the GFIs from the back side?
Well you just found another way to do this.
And yes my power supply is variac based!.
Talk about energy!
Sorry about your power supplies but you violated circuit ground.

http://stores.intuitwebsites.com/hstrial-writebid/-strse-9/ISS-Enprotech-ISS-/Detail.bok Pay him for manual copies.

At this level of energy speed, diodes become straight wires. Both ways. Jason and I both fought this effect only to realize what was going on.
Now if you are talking about capturing this with iron wire, it will conduct like a wire after capture. You use a HV scope probe or follow Otto's advice by just leaving your probes disconnected in close proximity.

Be forewarned any who attempt to build this circuit.

I have lost 3 power supplies that I have used over twenty years or more without a problem.

The circuit or something is generating an occasional large snap like a big capacitor discharge and takes out the power supply.

Even when I isolate the supply with diodes and an outboard cap, I have still had power supply failures.

I suggest anyone who wishes to experiment with this use a Variac, an isolation transformer and simple voltage doubler circuit to derive the 200 to 300 Volts DC required for it's operation. DO NOT USE YOUR GOOD SOLID STATE BENCH SUPPLY!!


I've got two repaired and one to go before I'm back on the bench, but I won't be using these supplies for this circuit.

Getting close to Halloween and this is spooky!

(P.S. anyone who can help me find a schematic for an ISS Enprotech 500 / 500 I will be very grateful)
« Last Edit: 2011-10-15, 03:51:09 by giantkiller »


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Sorry to hear that ION, Thanks for the warning.

I am unable to find the requested diagram this time  :(

My pot smoked last night, too low wattage, cannot seem to get a 1 watt easily without a min £££ order, any way i will introduce your zener mod tonight, this will at least cut the high voltage down across a new pot.
   
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