1. The transformer in Fig 7 is not the transformer you see in the video, though. This is an isolation transformer (possibly step-down) to be used in conjunction with the variac, to better control the current through the coils La/Lb.
I agree. The transformer's (T) main function is isolation and impedance matching to the LaLb coil (which is below 1Ω at 50Hz).
As such, it should be a step-down transformer, e.g. 230VAC to 5VAC and the secondary should be wound with very thick wire to support very high currents (think something along the line of a welding transformer when using it with an air-core LaLb).
Its primary winding should be powered by a Variac for ease of amplitude control.
3. As the schematic in Fig.7 suggests, this device is better suited for the ring, rather than a tube. Therefore, I would suggest winding the coils on ferrite cores, as can be seen in SR193 videos. The ring has to be placed between the cores, not the inner opening of the cores. Thus, the diameter of the ring should be comparable (actually slightly smaller) than the outer diameter of the core. If no core is used, the tube/ring diameter has to be comparable to the inner opening of the coil.
I agree. Using ferrite cores will increase the inductance of the LaLb coil and increase its impedance (lowering the average current flowing through it dramatically). This will make the system more similar to
Fig.4.
Also the copper/brass ring should be large like Yfree is suggesting.
However ferrite cores introduce several additional variables, namely:
- an additional acoustic vibration due to
magnetostriction,
- hysteresis losses
- variable permeability, saturation.
Take a look at
this video or rather listen to the sounds made by the coils and the core.
Also, listen to the sound of the Yoke device in
this video.
Both of these videos illustrate the acoustic vibration of a ferrite core predominantly due to magnetostriction.
4. The slit/opening in the tube/ring does not have to be paper thin. The slit/opening is there so that the ring/tube can become a turn, to pass the current through.
I still think that the slit must be thin, because an excessive air-gap width will attenuate beta current which is the fundamental operating principle for converting matter of the pipe to electric energy, in those types of devices.
Fast electrons have a limited range in air and they cannot cause secondary decay events in the gap which stops the "multiplication" of the beta current. Fortunately,
thin double-sided printed circuit boards are readily available.
The hard dielectric (e.g. a fiber glass double-sided PCB), which the ring or a short piece of tube is soldered to, also serves as a mechanical support of the ring/tube. The point of soldering has to be the only support point for the ring/tube, as this is a mechanical resonator.
Yes, that's very important. Think about making a bell when you are suspending the pipe/ring. When struck, the longer it rings acoustically, the better.
5. The most difficult part in tuning this device is finding the appropriate mechanical resonance of the ring, as it has many resonances and most of these resonances are non-working.
It certainly is the FIRST thing to do.
Coreless devices (such as Itsu's) vibrate the slotted pipe/ring due to time-varying
Ampere forces (in this case
magnetostriction is absent).
These Ampere forces exist:
a) within the LaLb coil itself
b) between the LaLb coil and the pipe/ring
c) within the pipe/ring itself
In practice, evoking acoustic vibrations by those forces requires 10s of Amps (or 100s A). Think - stick welding.
In this case, it would be useful to be able to see the acoustical vibrations of the slotted pipe/ring on a scope.
To be able to do that I'd make it ring like a bell by hitting it with a hammer or a screwdriver and sensing its acoustic vibrations with:
1) a high frequency air microphone connected to a scope, or...
2) a piezoelectric disk from a Xmas postcard glued to the pipe directly and a massive counterpoise, effectively making a piezo microphone out of the pipe/ring, or...
3) a microphone coil (a thin-wire multi-turn small solenoidal air core coil with low inter-winding capacitance) that senses minute movements of a small shard of a permanent magnet glued to the pipe/ring, or...
4) a piece of reflective kitchen aluminum foil glued to the pipe/ring, that reflects a laser beam from a laser pointer. This reflection should be sensed far away with a photodiode or phototransistor connected to a TIA and the scope. See how it is done in
this video.
Take your pick.
Warning: The acoustic vibrations will form a standing wave inside a long pipe (see
here) and if you are an unlucky fellow, then you will try to measure these vibrations at the antinode and see nothing.
Thus, move your measuring point a little, if you see nothing.
6. The current pulses for exciting vibrations of the ring have to be very strong (at least initially).
I think this will be the most difficult part. The pipe/ring is a
dead short and its impedance is several milliOhms (event at kHz). It will require a helluva driver/amplifier to vibrate it by
Ampere forces.Perhaps
Eddy Currents are a solution to this problem.
I'd appreciate suggestions how to attack this last point.
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Topic: Comments on the McFreey paper (Read 112850 times)
