Luc,

A DC-DC down converter is handy when you need to be able to vary your output voltage between the ranges of your supply and almost 0V. You do this of course by changing the pulse width. 100% will yield your full 170V, and 0% will yield 0V output. This is indeed what you've built. Try increasing the pulse width and watch your magnet rise even further. It should do this continuously until either your supply gives out due to current limitations, or your coil burns up.

As a test, connect your coil directly to your variable DC power supply and begin at 0V. Increase the voltage until the magnet levitates to the same height you had with the PWM supply you built, and I am sure you will find that the current and voltage from the DC supply is very close to the numbers I gave above, i.e. ~3VDC @ ~300mADC.

The only advantage gained from a switching power supply (i.e. the PWM supply you have built with your 555, switch and coil) and a linear variable DC power is efficiency, IF you need to vary the supply voltage. If for example you only needed a fixed 3V @ 300mA supply, it would be more efficient and practical to design a linear supply tailored to the application.

I am not sure what else you will want to do with your circuit, but if you want an efficient way of varying the strength of the magnetic field from your coil, then you have accomplished that. Linear supplies become inefficient when you turn the voltage quite low and draw high current, but at full voltage they are just as efficient as a switching power supply, or at least very close.

I've attached two scope shots matched to the shots wattsup posted, as it seems you have doubts that I did any testing. It's the best I can do with the time I have available, but I can assure you that the information is accurate. The yellow trace (coil voltage) scale is the far left, while the green trace (gate voltage) scale is to the right (-2V to 30V).

I encourage you to perform the measurements I did in addition to the DC power supply test. Measuring the coil voltage and current should be straight forward for you, and you will see that indeed you've converted 170V to about 3V or so, and 10mA to about 300mA or so.

Regards,
.99

Hi .99,

sorry you feel I was doubting you actually doing the test research since that was not my intent. I was just joking around since I'm not good at making reports like you have presented. It would take me a few pictures at least. You did a great job

You are also 100% correct that this circuit is not making a coil perform magnet levitation height more efficiently then using strait DC as far as current and voltage are concerned. I have tested what you mention above before starting this topic and have found that strait DC to be slightly more efficient which demonstrates that the circuit has losses (heat at the switch). I'm not claiming either to have found the holy grail of electronic circuits as I don't believe there is one.

What I'm trying to communicate here is that an air core coil inductive kickback has more punch on a permanent magnet then the energy used to create it.

That's it

I'm also suggesting that using an electronic component to do the switching (even though I used it in the video test 2) is not the ideal switch to use in this application even tough it shows an interesting effect.

You are a fast and smart individual as I can see and it is good to be honest and looking at this from all angles as a good show can be deceiving if we don't look at it all.

So the question is, can we use this inductive kickback energy to power a motor more efficiently then using strait DC will remain unknown I would say until we build and test it.

Thanks for sharing

Luc

Okay .99,

I understand and I'm sure you understand what I'm talking about.

I'll try to build something that can somewhat work on this principle and you can enjoy the video show when I post it.

Thanks for your time and willingness to help out.

Luc

Hi Peter,

well, no since one side would be in attraction mode but yes! if I change the coil polarity.

Luc

Hi .99,

if you can help with one more thing I would be gratefull since there is still one thing that no one has explained yet and I'm hopping you can. Why does the sens coil not pickup the rerouted energy and extend the scopes wave form more if it is the case that the energy is extended or what ever it is doing?

Thanks for your time.

Luc

Hi Luc.

Monitoring a coil's voltage does not always indicate what is going on there in terms of its current. The fact that the bottom portion of the coil voltage disappears when the diode is in-circuit, actually does indicate that a conversion is taking place. The conversion is from high voltage/low current, to high current/low voltage. If you zoom in when the diode is in-circuit, you will probably see a negative swing of about -0.65 Volts (from the previous -300V or so), but the current has shot up significantly. This is the indicator that "something" different is happening in the coil that is causing the increased magnetic power.

With no load (i.e. without a flyback diode), the coil sees almost an open circuit during its inductive kickback cycle. The same amount of energy (minus losses) must be conserved, so the coil voltage extends quite high in the reverse direction, but the current is quite small.

When the coil IS loaded during its inductive kickback cycle by placing the diode across it in reverse, the diode creates nearly a short circuit across the coil during this cycle, so the current has no choice but to increase by a large amount. It is this increase of current that you can not see by looking at the coil voltage, but this increased current is what is responsible for the much larger magnetic force being applied to your neo magnet.

Remember with coils, it is current that energizes them and produces a corresponding magnetic field, not voltage. With a heavy enough wire you could produce quite a strong magnetic field with only a few volts, as long as the source can supply a large current.

Hope that helps,
.99

Hi .99,

yes indeed that helps ... your written explanation was so good that I could actually visualize it as I was reading.

Thank you my friend for all your expertise you have given to this and other topics.

Luc

Yep, that goes for me too.

Error

Hi .99,

thanks for the reply

that's true! it could of been a mix of AC and DC. The flame left no markings what so ever. It was orange in color, much like Hydrogen burning.
In my setup half the full wave bridge rectifier positive side goes direct to the coil and the negative side goes through the mosfet. The soldering Iron goes to ground, so if I touch the coil on the mosfet side I activate the coil with half the DC voltage (80 vdc) of positive side of the bridge.

Let me know if you think this is worth reproducing to study it more.

Thanks

Luc

Hi .99

yes a total of 170vdc is at the capacitor but if I put my voltmeter between Earth Ground and each of the leads going to the coil (leads now disconnected from coil) I can only measure the positive side of the capacitor as the other side is blocked by the mosfet. So I can only be sure half the capacitor voltage is going through but since the mosfet fried when this originally happen then it is quite possible the full 170vdc of the cap was at the coil.

I hope this help you to understand

Let me know

Luc