[TCML] Sanity check for tesla coil measurments

[David Petzer <davepetzer@xxxxxxxxx>]

Hi all,

Looking for a bit of guidance on a singing Tesla coil project. It is my 
undergrad thesis project. Monash University Clayton (Melbourne Australia) has a 
big old rotating spark gap Tesla coil which they fire up every open day to make 
some sparks (Some pics at 
http://www.flickr.com/photos/39813220@N08/sets/72157624539910485/). The idea is 
to convert this coil to a solid state singing coil. It has been tried three 
times and still no Youtube video. Fourth time lucky right?

Just wanted to know if any of these measurements seamed to be clearly wrong. I 
have only just been bitten by the tesla coil bug and I am sure I could miss even 
a glaring error. 


The measurements will be used to produce an equivalent circuit model to put into 
PSIM so I can speck the MOSFET's or IGBT's for the project, and show power 
modulation through variable dead time to produce sound. 


The secondary coil is about three meters tall radius of 15.9cm. 2130 turns on 
secondary. 9 turns on primary. Interesting are the old glass and aluminium foil 
capacitors, and wooden pine supporting structures.

These were measurements made with an Agilent LCR meter, they tally well with 
physical dimension calculations.

Secondary inductance 135mH (primary disconnected and left open circuit)
Primary inductance 45uH (secondary disconnected and left open circuit) 
Resistance of secondary at 60kHz = 29ohms

These measurements were made by viewing the input current to the coil when 
supplied with a high impedance source of 100mV

Resonant frequency driving base of secondary coil, (primary disconnected and 
left open circuit) 58.7kHz
Resonant frequency driving top of primary coil with the base of primary and 
secondary connected and grounded 59.2kHz

These measurements were made by driving the top of  the primary coil with a few 
100mV at frequencies well below resonance, base of primary and secondary 
connected and grounded, voltage was measured at top of secondary.

Turns ratio (Vout/Vin) by measuring voltage at the top of the secondary
50Hz = 2.4
200Hz = 5.3
500Hz = 8
1000Hz = 8.8
Up to 4000 Hz where harmonic distortion of output voltage was noted turns ratio 
was about 9.6

Thanks in advance for any help.

Cheers,

David


      
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