Proof of concept - perturbing a static magnetic field

[bob.rennips]

Hey Kames, I like that nand gate pulser. Cheers.

[eldarion]

Grrrr....things fell apart here at home again, so it looks like I'll be sitting out the next few weeks.

I was in the middle of trying to build two switching power supplies; one to produce +60V and another to produce +150V.
I personally think that this is the way to go.  Feed the two voltages to the two coils and generate the correct pulse sequence--some interesting things should happen.

Oh well, this happens a lot.  This isn't like my previous message either, it looks like I am out for quite a while.

[bob.rennips]

As time permits I'm slowly moving forward. I have now got my variable pulse sequence hardware logic going that will feed into the mosfet drivers. The circuit schematic used is as per my previous postings on this thread without any changes other than pull down/pull up resistors where required.

I had the circuit driven at 35khz, volts per div are 5v. As you can see I have a well formed 12volt square wave. Note that this is the output from an inverted nand gate BEFORE going into the mosfet driver chip. The mosfet driver requires minimum 10v so this is more than enough.

The first scope shot shows two channels to drive two coils. As you can see the lower trace pulse sequence overlaps the higher trace pulse sequence for the first two pulses, then move to alternate shorter non overlapping pulses.

The second scope shot shows the exact same pulses except the timebase per div has been expanded so that rather than one pulse sequence being shown, 3 pulse sequences are shown. The photo has been cropped to show the bottom trace, trace2, only.

The next stage is to get the high side mosfet driver working with the IRF840. I don't see a problem in doing this, just a matter of getting some time together.

[Jdo300]

Hello All,

Valiant efforts I see here! I just wanted to make a quick comment concerning the permanent magnets. I strongly suggest that you NOT use NdFeB or other strong rare earth magnets for the PM of this device. These magnetic fields, though very strong, are very difficult to perturb. I believe that the idea is to use the pulses to couple with and perturb the magnetic field. The best magnets for the job would be the weak ceramic magnets (ceramic 5 or 8 ) that you can pick up at RadioShack. The field may be magnitudes weaker than the Neos but it would be much much easier to disturb with the pulse coils. Remember, it's the changing field we are after, not the strength of the field itself. So if we can kick even a weak field all over the place very quickly, we might get the results we week.

Just my 0.02 cents .

God Bless,
Jason O

[bob.rennips]

Thanks Jason. I'm planning on using an electromagnet to create the static field - so I can adjust the DC current for different field strengths.

But good point about using a weaker field. I had been planning on generating a large field. So I'll spin this plan on its head and start with a weaker field. Cheers.