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Re: [TCML] Table Top Tesla Coil



Hi Amir,


It will work as is, but the smaller the number of turns, the more "touchy" finding the best tap-point is. (the sweet-spot). This is because as you move along the spiral a distance X, the rate of change of the inductance, dL/dX, and hence the rate of frequency change df/dX is larger when X is small. Adding another cap to each string would lower the effective capacitance and thus allow you to use more of the primary coil for the same frequency since it is the product L x C that determines the frequency. But as I said, it should work as is. The numbers I have given you are from fairly simplified equations and you might want to run your design through javatc to get more accurate numbers but they are a good first approximation. +/- 5% and a convenient starting point..


Good Luck and please keep us posted,


Matt D



-----Original Message-----
From: Amir Mojarradi <ln2guy42@xxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Mon, Jul 15, 2013 11:24 pm
Subject: Re: [TCML] Table Top Tesla Coil



Hi Matt, 


You are correct. The outer diameter would be 10 in. 


Would 3.5 turns be a suitable number of turns to tap at or would you suggest 
making some changes in the overall design? 

Thank you for your help. 


Amir


-----Original Message-----
From: mddeming <mddeming@xxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Mon, Jul 15, 2013 3:58 pm
Subject: Re: [TCML] Table Top Tesla Coil


Hi Amir,


something isn't adding up here. If your start with a diameter of 4 in. and 
increase by 1 in on each turn, then 6 turns only yields 10 in diameter, not 11 
in. It looks like your coil will tune at about 3.5 turns.

Matt D


-----Original Message-----
From: Amir Mojarradi <ln2guy42@xxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Mon, Jul 15, 2013 4:37 pm
Subject: Re: [TCML] Table Top Tesla Coil


Hi Matt, 


Thank you for checking over my numbers. 


For the Primary Coil for the 2.5 inch x 11 inch secondary Tesla coil, here is 
what I have planned:


Inner Diameter: 4 inches
Number of Turns: 6 inches
Wire Diameter: 0.25 inches
Turn  Spacing: 0.25 inches
Outer Diameter: 11 inches
Length of Wire: 201.061 inches
Inductance: 13.473 uH


I calculated the resonant frequency for the secondary circuit to be 393.485 kHz. 


Please let me know your thoughts on these primary coil dimensions. Would you 
suggest any changes?


Thank you, 


Amir Mojarradi
Los Angeles, CA



-----Original Message-----
From: mddeming <mddeming@xxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Mon, Jul 15, 2013 7:26 am
Subject: Re: [TCML] Table Top Tesla Coil


Hi Amir,


So far, your numbers look good. However, you have said nothing about the 
dimensions of your primary coil. Since from the information you've given, your 
secondary resonant frequency will be near 390 KHz, to balance the primary will 
need to be about 3.33 uHy giving you the resonant frequency near 390 kHz


Matt D



-----Original Message-----
From: Amir Mojarradi <ln2guy42@xxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Sun, Jul 14, 2013 7:19 pm
Subject: [TCML] Table Top Tesla Coil


Hi everyone! 


I would love to hear your thoughts on the table top sized Tesla coil I am in the 




process of building. Specifically, I was wondering if I have chosen optimal 
values for the primary capacitance and dimensions for the top load. 


Any other comments on improving the design would be incredibly appreciated.


Here are the specifications:




Power Supply: 5,000 Volt, 60ma Neon Sign Transformer (with safety gap and Terry 
Filter)


Secondary Diameter: 2.5 inches (acrylic tubing)
Secondary Wire Gauge: 29
Secondary Winding Length: 11 inches
Secondary # of Turns: 900
Secondary Self Capacitance: 4.5 pF


Primary Capacitance: 0.0499 uF @ 12,000 volts (MMC of (12) Cornell-Dubillier 
942C20P15K-F 0.01 uF 2,000 volt capacitors; 2 parallel strings of 6 in series) 


Top Load: 8 inch diameter stainless steel sphere (11.4 pF) 


Spark Gap: (2) 1/8 inch diameter Tungsten Electrodes




Thank you so much for your help!


Amir Mojarradi
Los Angeles, California








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