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Just to be sure, you choke coils are 2.2 micro Henry, not 2 milli-Henry right?I wrapped 8 winds of 14 gauge enameled copper wire on a black ferrite core and got 5 micro-Henry according to my meter. Does that sound right?
Thanks, I think I can picture the last part.
So you are saying that the ferrite core needs to be between the work coil and the workpiece?
I found a good-sized oval ferrite core, about 4 cm on the long side and 3 cm tall. I was thinking of using that, but if I wrap the work coil perpendicular, like you usually do on cores, there will not be enough space on the inside to use it. If I wrap the work coil around the outside, then I have a lot od work space, but I don't know if that will help the efficiency. Do you think that it would help to wrap the work coil around the outside of a large oval ferrite core?
I did look this up and it suddenly dawned on me that thick speaker wire, like for car stereo, is a Litz wire. Just in case someone is looking where to find some, but I don't know how much less hot it will be.
I was thinking that you could make your own Litz wire. Unwrap an old transformer and make 20-40 loops, each would be long enough to make the coil. Twist each bundle, then braid enough bundles to make the gauge you want for the work coil.
When, the guy at the local car audio store is a liar. He said that the reason the reason that the 4 gauge car stereo wire was so expensive was that is was specifically made for AC conduction. Maybe they just say that to justify the price. It could be tested it since you could easily check for cross conduction. At least it looks right being braided.
Thank you for that info. I was not thinking of the chrome plated tubing to avoid cooling but as a way to improve the cooling while still using the water or air inside it. If it won't be an additional help, then the extra cost is not justified. If you have the time, could you please illustrate what you mean but your ferrite improvements for the work coil?Also, what is Litz wire?
Thanks, what about updates?
Thank you for this design and tutorial, it is excellent. I have not made it yet, but I have a few questions. If you have design updates, please share here or privately. Can you drive this circuit with an external oscillator to be able to tune accurately?Would modifying the caps and work coil to increase the resonant frequency help with efficiency? Is it possible to make an oval instead od round work coil?
I was thinking about the first half of the first sentence below. Also, what do you think of the using the chrome plated copper tubing, like for water delivery under sinks. There is an intense infrared emission during operation and the reflection may help hold down the heat transfer. I don't know if that would alter the capacitors for resonance.