Dr Ronald Stiffler SEC technology

[ramset]

A direct link to Stiffler's latest video

demonstrating "the Load does not impact the source "

https://www.youtube.com/watch?v=lxRbckLedjU
schematic and more to follow.
respectfully
Chet K

[erfandl]

Okay then, your oscillator works.  Try to seek for resonance with the chokes,  especially L3 and make the trimmer capacitor to cover a higher pF range.  (GBluer indicated a 2-512 pF variable.)  The base resistance then may also be varied. 
Each oscillator has its own 'soul'...   

thanks. but there is no 512 pF trimmer available  in my country. I found only 0-120 pF trimmer. is that help me ?

[gyulasun]

Yes, it can help you.  And you can always add fix capacitors in parallel with it if the 120 pF is not high enough.  (Of course the setting range suffers.)    You may have access to old AM pocket radio in which a plastic cased variable capacitor can be found, normally such has 2 x 260 or 2 x 300 pF variables.    Or you collect a range of fix capacitors like 22, 47, 100,  200 pF and place them in parallel in gradual combinations. 

[itsu]

Thanks Itsu.  Regarding the virtual ground to start up the oscillator: have you tried to connect the common point of the diodes to the negative (or maybe the positive) supply rail with a short piece of wire?   That my also help start up but without that longer piece of wire. 
If it works like that you may increase the potmeter setting to a higher value like 50-70 kOhm maybe to reduce dissiparion if the circuit lets it doing.
Very likely you need to retune the tank, we do not know how many pF the back plate of the LED board introduces into the tank, maybe it would detune the tank too far from 13.56 MHz, so keep this in mind.  it is possible the variable capacitor should be turned to its minimal pF setting or even to remove it and yet the back plate capacitance would be still higher than the originally needed 30-35 pF. 

Addition: with the tap at the 2nd turn, the 22 pF capacitor between the collector-emitter may need to be modified to a higher value to increase feedback, this way the oscillator may start-up without any virtual ground, this can be true for the tap at the 3rd turn too.   Try to set not higher than 60-70 mA collector current but that may be really needed for the 230V LED board. 

Do you have the specification of the LED board the manufacturer gave on it?  Input voltage I guess is 230V AC originally.   Now is the brightness we see close to the brightness this LED board produces from the mains with its original internal circuit?  I think these questions would be put by Nick too...   

Thanks,  Gyula

Gyula,

Still tap at 2th turn.
Replacing the virtual ground cliplead by a short wire to the negative or positive rail does have the same effect, the leds turn on brightly.

In this state, i can reduce the 100K pot setting for 60mA input current (32K) but that gives less brightness on the leds.

Replacing the 22pF cap in the above situation by a 47pF or a 100pF one does not make the oscillator start without a virtual ground (short lead to + or - or cliplead).



Going to the tap on 3th turn starts the oscillator only when inserting 100pF across collector/emitter (so without any virtual ground) but with much reduced brightness on the leds (100K pot still at 32K drawing 70mA).



Itsu

[gyulasun]

Hi Itsu,
Many thanks.  This may mean the series capacitance of the back plate of your LED board towards the conducting LEDs and the two diodes common point is small enough so that the variable capacitor can still be tuned for max brightness, I suppose?
Okay that a smaller current yields less brightness, I thought to reduce it so that such changes should not damage anything.
Gyula