The bifilar pancake coil at its resonant frequency

[icarus]

For people interested some replications of the mini exciter.

Cheers

Nelson Rocha

Please Nelson control your PM

Thanx

Icarus

[synchro1]

I think that many believe that because the voltage inverts across the coil,when the source current through the coil is interrupted,that the flow of current must also invert-change direction through the coil.

Yes,the voltage across the coil inverts,when the source current flowing through the coil is interrupted,but the current through the coil keeps flowing in the same direction-only now,the source is the collapsing magnetic field around the coil.


Brad

@Tinman,

Current reverses direction and travels in the same direction at the same time like the 60 Hz A.C. current in our overhead transmission lines; Like boarding a bus and moving toward the rear while the bus is accelerating forward. It may appear to a stationary observer that the bus passenger is standing still.

[TinselKoala]

Oh really? It goes both ways at the same time? I think I know some people like that. But the major transmission of electrical power over long distances doesn't.

High-voltage direct current (HVDC) is used to transmit large amounts of power over long distances or for interconnections between asynchronous grids. When electrical energy is to be transmitted over very long distances, the power lost in AC transmission becomes appreciable and it is less expensive to use direct current instead of alternating current. For a very long transmission line, these lower losses (and reduced construction cost of a DC line) can offset the additional cost of the required converter stations at each end.
HVDC is also used for submarine cables because AC cannot be supplied over distances of more than about 30 kilometres (19 mi), due to the fact that the cables produce too much reactive power[citation needed]. In these cases special high-voltage cables for DC are used. Submarine HVDC systems are often used to connect the electricity grids of islands, for example, between Great Britain and continental Europe, between Great Britain and Ireland, between Tasmania and the Australian mainland, and between the North and South Islands of New Zealand. Submarine connections up to 600 kilometres (370 mi) in length are presently in use.^[21]
HVDC links can be used to control problems in the grid with AC electricity flow. The power transmitted by an AC line increases as the phase angle between source end voltage and destination ends increases, but too large a phase angle will allow the systems at either end of the line to fall out of step. Since the power flow in a DC link is controlled independently of the phases of the AC networks at either end of the link, this phase angle limit does not exist, and a DC link is always able to transfer its full rated power. A DC link therefore stabilizes the AC grid at either end, since power flow and phase angle can then be controlled independently.
As an example, to adjust the flow of AC power on a hypothetical line between Seattle and Boston would require adjustment of the relative phase of the two regional electrical grids. This is an everyday occurrence in AC systems, but one that can become disrupted when AC system components fail and place unexpected loads on the remaining working grid system. With an HVDC line instead, such an interconnection would:
Convert AC in Seattle into HVDC;
Use HVDC for the 3,000 miles of cross-country transmission; and
Convert the HVDC to locally synchronized AC in Boston,
(and possibly in other cooperating cities along the transmission route). Such a system could be less prone to failure if parts of it were suddenly shut down. One example of a long DC transmission line is the Pacific DC Intertie located in the Western United States.

https://en.wikipedia.org/wiki/Electric_power_transmission


--And neither does AC over shorter distances.

[Magluvin]

@evostars,

Discharging a capacitor is like decanting water from a five gallon jug; Slow starting, followed by a strong gush  at .67, tapering off to a slow flow: Charging exactly the reverse, max charge rate at .33 capacity:

Are you saying that there is a delay in a cap discharge, due to the nature of the cap itself, or due to the impedance of the discharging device?

If we were to make a home made cap with foil, wax paper and say a straight copper wire to make end connections for each plate, which would be the better method of winding it? With the plate connection wires both starting at the beginning of the rolling, or 1 wire for the bottom plate at the beginning and the top plate wire at the end of the roll, and say its a 100 turns, would there be a difference in how the cap works in these 2 cases? Would one have more induction issues than the other?

Mags

[TinselKoala]

Look at the graph he posted, in "support" of that claim.

Where, on that graph, is the maximum rate of charge? Where, on that graph, is the maximum rate of discharge?