I've thought about syncing a high speed camera to a monochromatic light source and strobe it, the idea being to exceed the frequency of the mag field forming and collapsing by a factor of at least 4 or 5, a very expensive undertaking. 500k frames per second would be nice, then vary the light frequency, another expensive piece of equipment.
There's always the old iron filings on a piece of paper routine but that's not directly observing the field.
Fri, 23 Jul 2004 21:04:57. Now here's a new possibility, it's called Ferrofluidic, a unique magnetic liquid that can be manipulated by an external magnetic field. Ferrofluidic is the only material in which a magnetism and fluidity coexist. Patented by NASA in 1965 and sold as a kit. It can be purchased directly at (888) 455-9712 in 50cc bottles. This info came to me from a friend in July, 2004, I have got to check this out. I'm thinking of clear acrylic tubing, preferably flattened leaving a long narrow channel in its length and filled with this material. Seal both ends. Using a purpose made mount and tripod, attach this device perpendicular to the ground and approaching the secondary coil (or extra coil), making sure this instrument is at least as long as the coil under test and centered. Fire the coil while observing the material, move it closer, repeat exercise. What I'd like to see is the nodal points along the coil but if this works it may also pick up the primary and secondary swapping energy. Will Ferrofluidic show nodal points with a secondary injected with a Sweep Function Generator? How sensitive is it and how fast will it react?
Edmunds Scientific had some film-like material that they advertised as showing a visible pattern of any nearby mag field. I've checked through the last 10 catalogs and it seems to be a discontinued item.
Mon, 19 Jul 2004 21:04:57. Subject: Quarter Wavelength Frequency. Here's something along these lines from Antonio: "A very sensitive method to observe the resonances of a coil is to drive it through a tuned primary circuit, as in a Tesla coil. In place of the gap place a low-impedance square-wave generator, generating a frequency of about 1/100 of the expected resonance frequencies, and tune the primary circuit to find the resonances. At each of them you will see full beats in the voltage over the primary inductor. The observed oscillation frequency is the resonance frequency of the secondary too. There is no need then to observe what is happening in the secondary. The setup may be this, with a square wave generator made with a 555 and a buffer, see schematic below. Change C1 (easier) or a tap in L1 for tuning. I use a few capacitors and a large variable capacitor, all in parallel connection, as C1. When you find one of the resonances, slide a finger along the secondary coil, and you will see clearly where are the voltage nodes (zeros) along it, places where the presence of the finger causes less perturbation in the waveform. It's a funny experiment. It's easy to see many resonances in this way. Antonio Carlos M. de Queiroz
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