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Transmitting coil

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Alex McCown

Tue Jun 10 2008, 01:15AM

Registered Member #1528 Joined: Tue Jun 10 2008, 01:08AM
Location:
Posts: 3

hello
I am trying to build a transmitting coil to transmit electricity from one secondary to another

basically what I need to know is as follows

*what secondary ratio is best for transmitting
*what top load is best for transmitting
*what type of coil is best for transmitting (like vttc sgtc sstc drsstc exc)
*if I can get the transmitting coil to run off of 2.5kw what can I get from the receiving coil
*what specs should the receiving coil have

thank you,
Alex McCown

Steve Ward

Tue Jun 10 2008, 03:07AM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

basically what I need to know is as follows

Seems you might need to know more than you are asking about.

*what secondary ratio is best for transmitting

Best? a straight antenna would be best for transmitting, but you asked about tesla coils, which inherently are bad at transmitting, so id say go for tall and narrow, which gets closer to the straight wire antenna.

*what top load is best for transmitting

One that prevents sparks from forming. Sphere or toroid as usual, must be fairly large radius to keep sparks from shooting out.

*what type of coil is best for transmitting (like vttc sgtc sstc drsstc exc)

Well continuous wave (or semi-continuous) coils like VTTCs and SSTCs can radiate many kW at lower average power, and hence are easier to keep from making sparks, and also are nice because they can serve up power continuously.

*if I can get the transmitting coil to run off of 2.5kw what can I get from the receiving coil

Unlimited power! Well of course not, there is no free energy. You have provided almost no information to base an answer off of. Id say you might manage to transmit a few percent of that input power over a couple of winding-lengths away (say 10 feet), not very efficient.

*what specs should the receiving coil have

Probably identical to the transmitter.

Hazmatt_(The Underdog)

Tue Jun 10 2008, 07:07AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Transmitting any viable power really isn't realistic with a Tesla Coil. Why is that?

Well there's the Maximum Power Transfer Theorem which basically states that the source provides the maximum amount of power when its matched to the load. So when you have something like a battery with a 2 ohm internal loss, the maximum amount of power you can provide to a device will be when the device presents a 2 ohm load to the battery.

So what do you get out of this? Well.. at best 50% Efficiency in this case.

So how does this translate to Tesla Coils? Well, take your power input to a matched transmission line and you get 50% out if your coil is perfectly matched. But getting that 50% is really hard, I'm working on that.

So okay you have 50% out from what you started with right? Well, kinda not really. See the power drops off as a function P ~ 1/r^2, so you lose your power as an inverse square law proportion. That means at 1 meter you have your 50% recoverable, but at 2 meters you have ~12.5% recoverable because your power drops off by a factor of 4 @ 2 meters distance.

Well it gets worse yet. To recover your power at 1 or 2 meters means you need as stated, an identical tuned system, which means that system is matched for another 50% loss, so at 2 meters the maximum power transfer from system A to system B is 6.25%.

So from 1kw starting point, you end up with 62.5W on the other side for two perfect systems. So that's sorta where it stands, its kinda a raw deal, but that's how I see it.

Mates

Tue Jun 10 2008, 08:28AM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

Hazmatt_(The Underdog) wrote ...

So okay you have 50% out from what you started with right? Well, kinda not really. See the power drops off as a function P ~ 1/r^2, so you lose your power as an inverse square law proportion. That means at 1 meter you have your 50% recoverable, but at 2 meters you have ~12.5% recoverable because your power drops off by a factor of 4 @ 2 meters distance.

Well it gets worse yet. To recover your power at 1 or 2 meters means you need as stated, an identical tuned system, which means that system is matched for another 50% loss, so at 2 meters the maximum power transfer from system A to system B is 6.25%.

Iâ€™ve always thought that two matched grounded tesla coil transfer only minimum energy via the air (and actually these are unwanted losses) and most of the energy is transferred via the earth (works as a single wire). So the power losses rising with the square of the distance are so dramatic only in case of non-grounded systemsâ€¦ But maybe Iâ€™m completely wrong â€“ thatâ€™s only my idea how this energy transfer works and why the coils must be grounded to be a good power transmitterâ€¦

Alex McCown

Tue Jun 10 2008, 12:29PM