For now, I am moving back to the main goal of reproducing the output from the Don Smith device instead of focusing on the self-charging effect at the input.
Here are some shots of my current rig. I am taking the Zilano approach of using a single-stage step-down resonant transformer. I have measured the voltage around a traditional step-up CW/CCW dual coil rig I made and it didn't seem any more impressive than the voltage around the step-down rig.
The primary is 158 turns of 16 gauge magnet wire (scavenged from a defunct generator) wound around a 1-1/2" (nominal) PVC pipe core. The pipe is filled with about 20 little ferrite toroids of a high permeability type. When combined with the 10 nF cap bank seen in the photos, the resonant frequency is 62.5 KHz as can be determined from the ringdown in the scope shots. The PVM12 can be adjusted from about 48 KHz to about 68 KHz, so this combination works well and can be adjusted for resonance. The purpose of the cap array is to increase the voltage rating, there are 9x 10 nF caps (but only rated for 2 KV), to give 10 nF but rated for 6 KV. Good engineering practice for Tesla coils would be to put a high-value drain resistor across each one for safety but I haven't done this here.
The secondary is just a single turn for measurement purposes. As the scope shot shows, I am getting about 22 volts per turn, giving approximately 3500V across the primary at spark gap breakdown (assuming very close coupling here). The spark repetition rate is slightly erratic but averages about 100 per second. With a primary cap bank of 10 nF, this is 0.061J per spark, or about 6 watts of power into the primary. Next I will wind a secondary of probably about 12 turns to charge the ambient receiver cap to around 250V. Then a 250V GDT on the cap to pulse the primary of the "isolation transformer", where the overunity is supposed to happen. I'm still not convinced that the split/dual secondary coil is necessary but I will try both configurations.
Here are some shots of my current rig. I am taking the Zilano approach of using a single-stage step-down resonant transformer. I have measured the voltage around a traditional step-up CW/CCW dual coil rig I made and it didn't seem any more impressive than the voltage around the step-down rig.
The primary is 158 turns of 16 gauge magnet wire (scavenged from a defunct generator) wound around a 1-1/2" (nominal) PVC pipe core. The pipe is filled with about 20 little ferrite toroids of a high permeability type. When combined with the 10 nF cap bank seen in the photos, the resonant frequency is 62.5 KHz as can be determined from the ringdown in the scope shots. The PVM12 can be adjusted from about 48 KHz to about 68 KHz, so this combination works well and can be adjusted for resonance. The purpose of the cap array is to increase the voltage rating, there are 9x 10 nF caps (but only rated for 2 KV), to give 10 nF but rated for 6 KV. Good engineering practice for Tesla coils would be to put a high-value drain resistor across each one for safety but I haven't done this here.
The secondary is just a single turn for measurement purposes. As the scope shot shows, I am getting about 22 volts per turn, giving approximately 3500V across the primary at spark gap breakdown (assuming very close coupling here). The spark repetition rate is slightly erratic but averages about 100 per second. With a primary cap bank of 10 nF, this is 0.061J per spark, or about 6 watts of power into the primary. Next I will wind a secondary of probably about 12 turns to charge the ambient receiver cap to around 250V. Then a 250V GDT on the cap to pulse the primary of the "isolation transformer", where the overunity is supposed to happen. I'm still not convinced that the split/dual secondary coil is necessary but I will try both configurations.
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