Step 4: Wind the Primary Coil
Together with the primary capacitor, the primary coil makes up the LC resonator that drives the secondary coil. Because we want to transfer the energy in the primary circuit to the secondary circuit over several RF cycles, allowing the primary circuit to resonate, the coupling between the two coils is relatively low. This is why many spark gap coil primary coils are flat wound (this is not the case in solid state coils where the goal is to switch as much energy into the secondary circuit as possible with each cycle).
At this stage, you can use DeepFriedNeon's LC frequency and secondary coil calculators in order to find a combination that suits your components or you can use ScanTesla in order to "scan" for the configuration that will maximize the coil's perormance, however, I will not cover these approaches here. I think that I have found a primary/secondary combination that works reasonably well and if this is your first coil, I would advise you to follow what I did before you experiment on your own.
For my primary coil, I used a flat spiral made of 9 turns of thick stranded wire with 0.25" spacing tapped every quarter turn for tuning. If you can afford to use a flexible copper tube, then I recommend you do so because it is easier to tune and work with than insulated wire.
I used 4 supports made of 1" by 6" PVC pipe bolted down to the wooden base. Here is how I marked and drilled them to support the primary coil: http://www.loneoceans.com/labs/teslacoil2/sep9_pridesign.gif (with 5 tubes instead of 7 and 0.25" spacing instead of 0.5")
While you should wind the primary coil as neatly as you can, my coil worked fine even though the stranded wire didn't form a perfect spiral. See picture 5 for a diagram:
At this stage, you can use DeepFriedNeon's LC frequency and secondary coil calculators in order to find a combination that suits your components or you can use ScanTesla in order to "scan" for the configuration that will maximize the coil's perormance, however, I will not cover these approaches here. I think that I have found a primary/secondary combination that works reasonably well and if this is your first coil, I would advise you to follow what I did before you experiment on your own.
For my primary coil, I used a flat spiral made of 9 turns of thick stranded wire with 0.25" spacing tapped every quarter turn for tuning. If you can afford to use a flexible copper tube, then I recommend you do so because it is easier to tune and work with than insulated wire.
I used 4 supports made of 1" by 6" PVC pipe bolted down to the wooden base. Here is how I marked and drilled them to support the primary coil: http://www.loneoceans.com/labs/teslacoil2/sep9_pridesign.gif (with 5 tubes instead of 7 and 0.25" spacing instead of 0.5")
While you should wind the primary coil as neatly as you can, my coil worked fine even though the stranded wire didn't form a perfect spiral. See picture 5 for a diagram:
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