[TCML] more air core stuff
harvich at yahoo.com
Sun Mar 8 13:09:54 MST 2009
--- On Sat, 3/7/09, jimlux <jimlux at earthlink.net> wrote:
> From: jimlux <jimlux at earthlink.net>
> Subject: [TCML] more air core stuff
> To: "Tesla Coil Mailing List" <tesla at pupman.com>
> Date: Saturday, March 7, 2009, 8:11 PM
> Just running some numbers.. say you have 1000 turns of AWG22
> wire on a 20" diameter form (the winding would be about
> 1x1" in cross section). Pretty close to 1 Henry
I wound 140 ohms/ 23 gauge wire onto 3 inch ID smaller spools and arrived at 1000 ohms reactance(~ 2.4 H) @ 60 hz. Using a variac to keep the input below 120 volts to avoid overheating the wire, a pair of these can be inversely series resonated using 3 uf for each side, where the tuning for the pair is made according to the circumstances of their reactive amperage consumptions; which in turn means they can be tuned for magnetic opposition or agreement between the pair. This
procedure can produce a Q of an 11.5 fold voltage rise between a closely spaced pair of the 12 lb coils. Next the input wires to one side are removed after the circuit was tuned for a 1 inch separation. The former input wires are shorted to make for a secondary air core transformer @ 60 hz,(not a high frequency tesla coil. A smaller bathroom night light is given as that secondaries load. Both of these systems in simultaneous operation are pictured at both 60 volts and 90 volts input, which is the 1000 volt limit for this volume of wire.
1000 ohm 60 hz reactance coils,23 gauge/140 ohms DC resistance/ 60 volt input
TOP; Inversely series resonated pair showing 693 volts between them
BOTTOM; Rt coil reconfigured as air core secondary with nite-lite bulb as load showing 79 volts/ 26 ma vs 60 volt input with left lite at 60 volts input showing that more power can be transferred thru the air then if the same load were directly wire connected to its source.
90 Volt input to 60 hz resonances, top pair produces 1000 volts between them. Bottom air core secondary has input of .49A from primary,@ 435 volts resonant voltage rise producing 135 volts secondary volts with bulb taking 35.7 ma from coil/cap circulation of 143.1 ma. Paradoxically the meter showing the relative differences between the 435 volts and 135 volts on secondary reads 0 volts. Apparently Isolated voltage rises cannot be compared without making the autotransformer connection.
> OK, that's about a mile of wire (5235 ft), and will
> have a DC resistance of 87 ohms and be about 10 pounds of
> You can see why iron cores might be popular (e.g. a LOT
> less wire, which would reduce the resistance and the copper
>From what I have observed, iron core coils do not resonate well at all, when considering what the ideal vs real behavior by text book calculations. Even the air core 12 lb coils are limited in their real behavior by a very large internal capacity. However I was quite surprised to find that they function almost equally well in a tank circuit which provides for the practicallity of using them in a secondary power factor correction scheme, which does not seem to be addressed in the TC community, where power factor correction is always applied concerning the primary, and not the secondary. I arrived at a particular quandary when this was addressed at alternator frequency of 465 hz, where the VAR reading of input showed 6 times less a value then what the tesla tank circuit should involve as transfers of joule energy per time period.
Sincerely Harvey D Norris
> In a TC application, say you're using it as a charging
> choke with an rms current of 1A.. that's about 90W
> you're going to be dissipating. On a 10 kW coil,
> that's 1%
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