Hi All, Thanks for the reply.
I did try few suggestions, Gy, the DC straight to the coil did give me only 0.17 vdc at the out
same parameters input.
but at several hertz (low freq) the in= out.
I did two test at 0.4vpp Sq 50% ratio, and 1.5dc on top of the 0.4vac pp
Note on the Pictures I am taking the output at the Drain.
0.4 vpp should not conduct the mosfet!.especially passing the diac threshold
maybe several of this circuit in cascade might increase the output.
an other thing I don't mention any current value. should be in the ma range.
I am going to invest more around various similar design.

I guess my test is to get a very low voltage at the input and get kw's at the output for self power gen.
Erol

Hi Erol,

I edited a little your previous schematic to show input waveforms and that no need for the input capacitor, you can directly connect the gate electrode to the output of the square wave generator. Both A and B waveform I drew are ok for driving directly the FET, the waveform B that has no negative portion would be good also for wattsup suggestion when you omit the FET and the generator output would go directly to the coil input where the drain electrode was earlier and the generator ground to the 1uF's cap negative point of course as earlier.  Try to control the output voltage level of the generator, both in case with the FET and without the FET, to check how the DC output depends on the input AC amplitude.
With the FET in place, you may find a generator output amplitude beyond which the DC output would not increase any significantly but a little. IF your FET's gate-source threshold voltage, V_TH is around (say) 3V, then the optimal square wave amplitude may be between 3-3.5V maximum with respect to the zero line, waveform B in the drawing, and 6-7V peak to peak if you  have waveform A coming from the generator.
In case you do not use the series capacitor between the generator output and the FET gate, then you drive the FET from the generator low impedance output, the FET self capacitances can charge up and discharge more rapidly, and when you use the series capacitor then you drive the FET with a higher impedance (the 180nF or the earlier 1uF coupling isolates a little) and the FET self capacitances can charge up or discharge slowerly, all this affects the output DC voltage.

Please check how much the DC output voltage across the 1uF capacitor is loadable: when you measure say 16-17V DC output, place say a 10kOhm resistor across the capacitor and watch the voltmeter, ok? This way you can judge how the output is loadable and how much hard work you need to do for getting higher output power.

rgds,  Gyula

NOTICE 1:  If you place the LED to the drain as you show, then keep in mind that it has a forward voltage drop of 3.2V if it a white or a 1.6-1.7V drop if it is a red LED, this means the DC voltage across the 1uF output cap cannot be higher than the forward voltage drop  of the LED, ok?

NOTICE 2:  what kind of diac do you speak of?  In your schematic there is nowhere any diac...  and if you mean it is in the FET, forget it and study the equivalent schematic of a power MOSFET.

Hi All, Thanks for the reply.
I did try few suggestions, Gy, the DC straight to the coil did give me only 0.17 vdc at the out
same parameters input.
but at several hertz (low freq) the in= out.
I did two test at 0.4vpp Sq 50% ratio, and 1.5dc on top of the 0.4vac pp
Note on the Pictures I am taking the output at the Drain.
0.4 vpp should not conduct the mosfet!.especially passing the diac threshold
maybe several of this circuit in cascade might increase the output.
an other thing I don't mention any current value. should be in the ma range.
I am going to invest more around various similar design.

I guess my test is to get a very low voltage at the input and get kw's at the output for self power gen.
Erol

ok , did some measurements,I plugged the gen directly to the coil, now we have a regular LC Circuit.you think...

Step1: 3vpp SQ no DC components, 10% ratio, the output on the cap is :
-from 1hz to 10khz  Out =in as an image of the input signal, but goes down in amplitude as we approach the 5-10khz
-and 10khz to 20khz the signal is reduced to zero!.

Step2: 3vpp SQ with 1.5vdc 10% ratio, the out is:
-below 10khz the out = in as above
-10khz and up we got a straight line at 1.5vdc

so if  dc show up at the input it is transferred to out directly that's all

the mosfet configuration gives some realty different results!
BTW I did not see ANY resonance freq on the whole range!

I am back on the SM open frame configuration TPU, I did increase some number of loops coils, I got more currents on the output by cop2 when the out is in short cc. the input current does not change at all.
very promising!
later
E