All,
Since CaptLoz is not responding to Itsu, I will propose the input scheme I believe Chris is using for his device. I had stated earlier that there is no way for a single mosfet circuit to return energy to the power supply but that is not correct and I know better from past experience so, I'm blaming my 79 years young as the problem!
Anyway, I've attached a schematic and scope pix of the input circuit and will explain how it works. Ch1(yel) is the input pulse to the mosfet, CH2(blu) is the power supply voltage, CH3(pnk) is the output voltage across the drain, CH4(grn) is the current in L1, and Math(red) is the input power.
Initially, L1 is connected between + and ground via M1 and current begins to ramp up linearly. At a given point in time M1 is turned off and the current in L1 starts to fall as the voltage across L1 attempts to reverse. This action can not happen instantaneously however due to the capacitance that appears at the mosfet drain or Coss plus the parasitic capacitance of L1. So, this total capacitance will begin to charge and we will see a half sine wave at the output of the drain as long as the mosfet is not going into avalanche. When the voltage across the capacitance has reached a peak, the energy it contains will nearly equal the energy stored in L1 and the current in L1 will be zero.
Now, the charged capacitance will use L1 for the discharge path back to the + power source and will discharge back to zero volts and the current in L1 will now be negative and nearly equal to the positive peak current reached during the charging phase. This is when the energy stored in C1 returns to the power supply as seen by the negative current and power on the scope traces. Notice the relatively low net average input power of 43.7mw when the average input power for just the positive half of the cycle is 747.7mw in the 2nd scope pix.
I personally did not use this type of input circuit when testing my variations of the POC device but will give it another try to see if there is any possible OU.
Regards, Pm
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