Hi Joshua,
The toroid size will affect how many simultaneous spark streamers are produced. A smaller toroid will give a greater number of streamers, whereas a larger toroid will produce fewer streamers. If the toroid is too large then sparks might not break out at all unless you use a breakout point on the toroid. I happen to like a toroid size that produces two streamers which alternate side to side at opposite sides of the toroid. The toroid size that will create this situation depends on the input power to the Tesla coil. As an example, my TT-42 coil which produced 42" sparks, had a 4" x 13" smooth toroid, and used about 650 watts. Â
To wind the coils I use a gear motor to rotate the form at a somewhat slow speed, along with a foot switch to control the motor speed to allow for smooth starts and stops. I guide the wire by hand onto the form as the form rotates.Â
John Â
On Thu, Nov 11, 2021, 11:11 AM Joshua Thomas <joshuafthomas@xxxxxxxxx>
wrote:
> Hello all,
>
> Thanks for your earlier help. I've got the varnish drying on my new
> secondary coil, which I'm fairly sure was my problem. By the way, if anyone
> knows a good way to wind coils with few gaps I'm interested. I made a jig
> for winding and used a cordless drill, but even still I get the occasional
> gap in the winds. Is this just one of those "experience and patience"
> things?
>
> On to my real question: Is there a method for sizing a topload correctly
> for a coil? Assuming a toroid, you can choose different dimensions that
> give the same effective surface area and therefore the same effective
> capacitance. Are there useful rules-of-thumb for the proper sizing of a
> topload, as a function of the other parameters of a TC?
>
> Thanks in advance,
>
> Joshua Thomas