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Old 06-11-2011, 11:05 PM
Farmhand Farmhand is offline
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Join Date: Jun 2010
Location: Australia
Posts: 3,389
Originally Posted by cody View Post
I wouldnt say that. The high frequency alternators used by Marconi were actually tesla's invention. They later became known as alexanderson alternators. Either way they were teslas design and he used them a lot for his wireless system. But yes, for his final design he did say he preferred using DC, but either will work. My main reason for suggesting it is because i think its the easiest way to really comprehend how to tune the system and how different things you do effect the tuning. Personally i have found a function generator with a built in frequency counter to be the best learning tool for understanding tuning of the system. I had built oscillator circuits and ran many tests like you are doing and thought i understood the tuning, but it wasnt until i got a decent function generator that i really got a grasp on it. But thats just me.

I looked at your circuit again and it looks to me like a DC resonant charging circuit except you are using a transistor instead of a spark gap. Thats an interesting idea, i like it. I wonder if it would work better if you put in a de q-ing diode between the battery and the inductors. Here is a typical DC resonant charging circuit. See the first capacitor after the bridge rectifier, that is basically your battery. If you add the diode it shoud ensure that no current flows back into the battery before the transistor fires.

So it would look like this:

If you want to read some of the theory of the circuit and why im suggesting to try a diode you can read here:
DC Tesla Coil design
Yes i see, I would like to try as many things as I can, one of them being an AC square wave. It doesn't make sense to "not' give it a go. If a function generator is not too expensive I will see if i can get one, I should have one anyway by the sound of it.

I actually already have the de-Q-ing diode, it is the IN5408 diode on the top input rail, although I only just realised that is what it is now..

I do these things from intuition but I don't really know why. However for the desulfator it was a bad idea because the return from the charge battery can't get back to the source battery, that is why my 470 uf cap across the rails blew up like a balloon.

I decided to try this method to get some good effect without a spark gap. I imagine that if I use a higher frequency then i will need to use a smaller inductor and cap and vice-versa.

I have a small 6800 pf cap in parallel with the variable cap. which is 40pf to 1300pf, and this seems to work very well as an adjustment window for a 320uH inductor at 50 Khz. But that will all go out the window when i get more frequency.

I wrapped the remaining cylinder above the resonator coil with aluminum to increase the capacitance of the top load and it seems to be better but the foil has edges and there is radiative losses on the foil now as well as the coil.

None of which is really important, until i get resonance I will not know what radiate's what. I think the best option would be an aluminium tube flared at the end and slotted which can be slid over the PVC pipe above the resonator coil, this is where the resonator coil should be attached the top of metal tube then supports the top load. The more the EM wave radiation that is suppressed the better.

The rain is easing so after I mop up some water I'll try to make some neat bases.

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