Self running coil?

[cody]

Ok so you can only tune the oscilator with L and probally C as well, very interesting. I would probally still use resistance so you use the least amount of power to trigger the gate. Ive run some more figures for you. With the Main toroid of 117mH and with the 0.002uf cap the resonant frequency is 10,406 Hz. Im going to go with the assumption that the oscillating trigger toroid needs to resonate at that frequency too. Using your other toroid at 19mH as the oscilating trigger you dont have enough inductance to get to that low of a frequency. But i believe we should be able to add capacitance to reach the frequency. At 19mh you will need to add 0.012317uf capacitance to the trigger toroid. Im still not sure if you need to put it in series or parallel with the trigger toroid, you may have to test that. Or maybe that wont work. The other option of course would be to wind another trigger coil with higher inductance and use your magnets to tune the inductance on the trigger core, im assuming thats how your tuning it now. Its hard to say exactly what inductance you need because i dont know the self capacitance of the coil so you may just have to start adding turns if you want to go that route. The other option would be to decrease the capacitance on your main toroid. This would increase the resonant frequency to a level that your trigger toroid has a frequency range in. Ill recalculate the frequencys if you decide to go that route. You should be able to use a lower voltage once you get the trigger toroid in resonance because it will develope resonant rise to give you a higher voltage for your gate i think. Unfortunatly i dont think your going to be able to hit the optimum voltage level for your setup due to the low amperage capabilities of your toriod. But thats ok, we can still learn a lot from it. If you decide to make a new main toroid sometime, we can do some calculations to engineer it up for best preformance at a desired voltage level. Keep us posted and great work!

Cody

[gotoluc]

Ok so you can only tune the oscilator with L and probally C as well, very interesting. I would probally still use resistance so you use the least amount of power to trigger the gate. Ive run some more figures for you. With the Main toroid of 117mH and with the 0.002uf cap the resonant frequency is 10,406 Hz. Im going to go with the assumption that the oscillating trigger toroid needs to resonate at that frequency too. Using your other toroid at 19mH as the oscilating trigger you dont have enough inductance to get to that low of a frequency. But i believe we should be able to add capacitance to reach the frequency. At 19mh you will need to add 0.012317uf capacitance to the trigger toroid. Im still not sure if you need to put it in series or parallel with the trigger toroid, you may have to test that. Or maybe that wont work. The other option of course would be to wind another trigger coil with higher inductance and use your magnets to tune the inductance on the trigger core, im assuming thats how your tuning it now. Its hard to say exactly what inductance you need because i dont know the self capacitance of the coil so you may just have to start adding turns if you want to go that route. The other option would be to decrease the capacitance on your main toroid. This would increase the resonant frequency to a level that your trigger toroid has a frequency range in. Ill recalculate the frequencys if you decide to go that route. You should be able to use a lower voltage once you get the trigger toroid in resonance because it will develope resonant rise to give you a higher voltage for your gate i think. Unfortunatly i dont think your going to be able to hit the optimum voltage level for your setup due to the low amperage capabilities of your toriod. But thats ok, we can still learn a lot from it. If you decide to make a new main toroid sometime, we can do some calculations to engineer it up for best preformance at a desired voltage level. Keep us posted and great work!

Cody

Thanks for your reply Cody

The .002uf cap was not used in the setup I gave you in the previous page.

No tuning caps are needed. It's better this way since they can be cause of energy losses. To tune to Resonance I only need to change my inductance value of my main toroid and pulse toroid by adjusting the distance of the magnet on each.

So my question to you is, if I can get it to self oscillate and resonate from range of 14KHz to 30KHz without tuning caps is 12vdc too high for the toroid and just wasting energy?

Thanks for your time

Luc

[cody]

Oh, i see. Well i think you should be fine then. Sorry i cant give you a resonant frequency without the cap, but i bet you already have an idea of what it is. The parallel tank opperates in a mode of circulating currents, where as with out the cap you are in a transient mode, the transients no doubt are what was charging your batteries on the front end. So the voltage should just be limited to the measured input current. So you can go as high as you want with the voltage as long as the current your drawing is not above 0.142 amps, actually i would recommend staying well below that figure, at least below half of it which is 0.071A. If you have one of those IR thermometers you can just take the temperature of the coil, if it gets warm, your wasting energy. Going to high with the voltage it will probally destroy your transistors, transients are well known to kill transistors real fast. But what the heck, may as well push it and see what happens Good luck getting both your toroids tuned on the same resonant frequency, if there is anyone that can do it, im sure its you

cody

[gotoluc]

Hi everyone,

I made a new video to seek more answers for those who know the answers to all these things

Link to video: YouTube - Self Running Coil test 14

Please post your "educated" explanations as to why 2 coils of the same inductance behave in such a different way.

Thanks for your time

Luc

[gotoluc]

Oh, i see. Well i think you should be fine then. Sorry i cant give you a resonant frequency without the cap, but i bet you already have an idea of what it is. The parallel tank opperates in a mode of circulating currents, where as with out the cap you are in a transient mode, the transients no doubt are what was charging your batteries on the front end. So the voltage should just be limited to the measured input current. So you can go as high as you want with the voltage as long as the current your drawing is not above 0.142 amps, actually i would recommend staying well below that figure, at least below half of it which is 0.071A. If you have one of those IR thermometers you can just take the temperature of the coil, if it gets warm, your wasting energy. Going to high with the voltage it will probally destroy your transistors, transients are well known to kill transistors real fast. But what the heck, may as well push it and see what happens Good luck getting both your toroids tuned on the same resonant frequency, if there is anyone that can do it, im sure its you

cody

Thanks Cody

I'm keeping it way way lower than 0.142 amps ... I'm actually trying to get it to go minus

Thanks for sharing

Luc

[cody]

Ok i think i know what may be giving you those results with the different coils. Have you tried retuning with the brooks coil? Inductance is not the only parameter for resonance in a coil, capacitance is just as important. Each coil has inductance as well as self capacitance. Capacitance is created in a coil due to the turns being close to eachother but not touching, like capacitor plates. I suspect that although both coils have the same inductance, they have different capacitance, its not so easy to measure this, thats what i was talking about earlier. So i believe your brooks coil has a different resonant frequency due to a different capacitance. I believe that is what is mainly causing the effect, but i dont know for sure how much of a role the magnet is playing.

cody

[gotoluc]

Ok i think i know what may be giving you those results with the different coils. Have you tried retuning with the brooks coil? Inductance is not the only parameter for resonance in a coil, capacitance is just as important. Each coil has inductance as well as self capacitance. Capacitance is created in a coil due to the turns being close to eachother but not touching, like capacitor plates. I suspect that although both coils have the same inductance, they have different capacitance, its not so easy to measure this, thats what i was talking about earlier. So i believe your brooks coil has a different resonant frequency due to a different capacitance. I believe that is what is mainly causing the effect, but i dont know for sure how much of a role the magnet is playing.

cody

Hi Cody,

I swept the complete frequency spectrum with the Brooks coil and nothing happens!... no resonance or hot spot to be found.

Possibly the difference between the to coils is the toroid has 2 separate coils and connected in series. This may cause a very small delay (ping pong) between each half of the toroid. Once this action is combined with the MOSFET's capacitance it may start to resonate.

This is what I think at this time since the effect only happens with MOSFET's (not with transistors) and the other hint is a different model of mosfet gives a different resonating frequency.

Let me know what you think of this explanation.

Luc

[rave154]

LUC,

see attatchment,

i added a 1 OHM resistor shown... with the scope across it, running at 1KHz @ 50% duty.... with the 1K resistor scope showed 4.4mv RMS

with a 10K resistor scope showed 1.6mv RMS.

hopefully i connected this correctly? if not, tell me where the shunt needs to go and ill re-do it pronto

hope this helps ( eventually )

[gotoluc]

LUC,

see attatchment,

i added a 1 OHM resistor shown... with the scope across it, running at 1KHz @ 50% duty.... with the 1K resistor scope showed 4.4mv RMS

with a 10K resistor scope showed 1.6mv RMS.

hopefully i connected this correctly? if not, tell me where the shunt needs to go and ill re-do it pronto

hope this helps ( eventually )

Hi David,

yes, it looks well done!... I knew the results would be less current but I wanted you to see it. You can try going above 10K to find the point where it starts to affect the gate pulse. Maybe use a 20K or 50K pot and once you find the max resistance measure the pot and you will know the value.

To be able to scope the gate and the 1 Ohm shunt at the same time you will need to move the shunt between the ground and the current limiting resistor since your scope probes have a common ground. So both scope probe ground are connected at ground and the clip on the other side of shunt and the other clip at gate. This way you can see both at the same time.

Let me know how high of a current limiting resistor you can go and also do the math to calculate the Wattage the gate really needs to operate.

Thanks for your time

Luc

[cody]

Hmm... well i find it curious that you cant find a resonant point with the brooks coil, every coil should have a resonant point as far as i know Interesting thoughts you have, honestly i dont know. Playing with mosfet capacitance is not something i really have experiance with. As far as whats going on in your toroid, your guess is as good as anyones at this point i think, dont really know anyone that makes them like that to compare it to. You may be able to run one of those magnetic field simulations on it, a few guys on the forum use that sometimes. Oh and by the way, i saw your post a while back about some toroids being steel that was painted so i went to check the toroid i wound that took like 2 hours, scraped the outside and sure enough theres steel in there Probally helps explain why i wasnt able to get the same effects as you, but i was also using a BJT, i didnt know how much the mosfet was playing a role. May have to get it back out a try again.

cody

[gotoluc]

Hmm... well i find it curious that you cant find a resonant point with the brooks coil, every coil should have a resonant point as far as i know Interesting thoughts you have, honestly i dont know. Playing with mosfet capacitance is not something i really have experiance with. As far as whats going on in your toroid, your guess is as good as anyones at this point i think, dont really know anyone that makes them like that to compare it to. You may be able to run one of those magnetic field simulations on it, a few guys on the forum use that sometimes. Oh and by the way, i saw your post a while back about some toroids being steel that was painted so i went to check the toroid i wound that took like 2 hours, scraped the outside and sure enough theres steel in there Probally helps explain why i wasnt able to get the same effects as you, but i was also using a BJT, i didnt know how much the mosfet was playing a role. May have to get it back out a try again.

cody

Yes, a steel core replication would be a problem Next one is a mosfet is needed.

Wait a bit before you start winding more toroids. I'll have an update soon.

Luc

[gotoluc]

Hi all,

thanks for your input as to why the differences between the 2 coils. I will make another video when I have time that will have a coil of exact resistance and inductance and we can continue from there.

Here is an update on the self pulsing coil at this time.

Using a IRF640 it is self pulsing at 20KHz with 3vdc input at 14uA + or - 0.5uA

Channel 1 (green) is across the drain and source and Channel 2 (yellow) is across the gate and source. Both probe grounds are connected to source.

Take note of the beautiful Sine Wave the pulse coil is now making to trigger the mosfet gate. I think this is a new and ideal way of triggering a MOSFET.

If anyone feels up to the task, please look up the specs of the IRF640 and do a calculation of an approximate wattage needed to keep its gate triggered at 20KHz please feel free to do so and post your results.

Thanks all for sharing

Luc

Scope Shot:

[rave154]

LUC,attatched are two scope shots..

frequency is 1KHz and 50% duty in both shots

1k.jpg is with the pot set to about 1k.. normal stuff

47k.jpg is with the pot all the way up... notice the ringing in both the gate and the shunt..also... as i turn the pot up from a low value to a high one... when i reach the point when the ringing shows up, the coil starts whining/singing

this circuit was using my FG (3.3V DC ) through the opto...to the mosfet
the shunt is 1 OHM placed between ground and the pot

[gotoluc]

Hi everyone,

I made a new video to try to explain to the best of my understanding what makes this circuit work.

You can watch the video if you want but it's kind of boring as I'm not doing all that much.

Link to Video: YouTube - Self Running Coil test 15

Here is how I understand it at this time.

A magnet is needed, a ferrite core seems to be important also but what I think is very important is INDUCTANCE. This is what I mostly say in the above video, so you can watch it if you want or just read this.

Lets say we have a toroid or an open end FERRITE core coil an its inductance is 1 Henry. We know by adding a permanent magnet to the core the coils inductance will drop depending on the strength of the magnet or the saturation point of the core.

I'm quite sure the effect of returned energy works best with the strongest magnet! BUT as I stated above if the magnet is strong you may be left with next to no inductance. The 1 Henry coil you start with can easily go down to 10mH (Milli Henry)

What maybe happening when a permanent magnet (PM) is added to a coils core is when the coil is energized its electromagnetic field pushes against the permanent magnet field and once the coil is switched off the PM flux bounces back. This is where the return energy is coming from.

Now if we think about it, then we want the most powerful bounce back. So we want a strong magnet!... BUT a strong magnet will reduce your inductance next to nothing as stated above!... who cares, just build it right!... Wrong!... Inductance is what your coil needs to be able to create a strong Electromagnetic field to push against those strong magnets. So if you're left with only 10mH your coil will need a high voltage with much current to be able to create a strong enough push against the PM.

Now for the other problem. If you wind a Mega Inductance coil that reaches the 10 Henry mark it will need much wire length... who cares, just build it right!... Wrong!...wire length give resistance and resistance gives energy losses and not to mention coil reaction time (electromagnetic field building time).

So all these things need to be considered to get the right balance. So what do we do?

I have found and been trying to demonstrate and share since my ORBO replication that if you wind 2 coils in perfect half moons on a ferrite core the Inductance is close to double then the standard single coil toroid. Would this not be a coil design to consider for the above project?... hum... let's see, twice the inductance and no extra resistance then the standard coil. Sounds good to me! but you decide.

I built mine with 30 AWG which has much resistance and ended with only 6.9 Ohms and over 1 Henry inductance. I would recommend using 20 AWG or a thicker wire if your cores are large enough and wind it to 2 Henry or more if you can. But like I said many things need to be considered, like the total coil resistance, coil reactance time, PM strength to core saturation limit, the right inductance to push the pm field and also the right inductance to bring the coil to resonance. Yes! Resonance, another area to consider and important if you want the coil to be efficient.

Resonance is what's going on when I've been demonstrating the energy going back to the source. This is why I started this topic to bring this possibility to light. JLN has not found this effect yet, as I think his residual inductance is very small with the magnets used. He would need a much high frequency then he's been using to see it. However I do agree with him that the energy comes from magnets push back when coil is switched off. The other thing that is needed is a MOSFET as switch to see the resonance effect unless you add capacitance. It appears that the built in capacitance of a mosfet is what is most likely bringing the coil to resonance. I tried it with a regular transistor and nothing happens.

The other interesting finding I have is, the mosfet can self oscillate (switch) itself IF the right combination of inductance between the main coil and pulse coil (added between gate & source) as long as the circuit is tuned to the resonance range. By using a 3vdc feed, my dual coil toroid, IRF640 and tuning coil have achieved resonance to any frequency I want between 5KHz to 50KHz WITHOUT the use of capacitors. Many of the frequency Inductance values have been documented and someone more knowledgeable than me is working out a formula that will be shared with all.

The above is the description to the best of my ability at this time of what is going on in the circuit at this time.

Hope this helps some to better understanding what I've been trying to share.

Luc

[gotoluc]

LUC,attatched are two scope shots..

frequency is 1KHz and 50% duty in both shots

1k.jpg is with the pot set to about 1k.. normal stuff

47k.jpg is with the pot all the way up... notice the ringing in both the gate and the shunt..also... as i turn the pot up from a low value to a high one... when i reach the point when the ringing shows up, the coil starts whining/singing

this circuit was using my FG (3.3V DC ) through the opto...to the mosfet
the shunt is 1 OHM placed between ground and the pot

Thanks David for doing this test

My guess is the green trace is the gate probe and the yellow is the shunt... is this right?

Why is the gate at 2.97vpp on the first scope shot and up to 13.59vpp on the second shot?

The IRF640 would need about 8.5vpp to start working. I don't quite understand this. Also, the pot should be turned a little back down from the point the gate pulse starts looking bad. Then measure the resistance so you know what the maximum resistor you can add without affecting the gate pulse.

Luc