Rene/Meissner EMF Higher Voltage Charger Variant

[gyulasun]

Hi Tyson,

Well, had you included the 30V supply in the schematic I would have considered it     you did include the 20V
in two schematics preceeding the last schema above, this is why I thought you used 20V again. 
At 30V supply  the secondary coils voltage transformered during the ON time of the primary coils is surely
higher than the 12V battery to be charged so the 1:1 winding ratio sounds ok.

But it is always good to tests some variations like making two - two parallel groups from the 4 secondary coils
and connecting these groups in series as I wrote yesterday.   

Regarding the diode bridge, quasi all such high current high voltage bridges are intended for mains frequencies,
their switching speed may not be sufficient for your circuit that may work in the some kHz or ten kHz range. 
https://www.fairchildsemi.com/datasheets/GB/GBPC1506.pdf  data sheet deals with 60Hz frequency (Fig 1 and 2).
Maybe it would be worth to assemble a diode bridge from 4 fast diodes like the UF4007 etc.

Also, another variation here would be to use a full wave voltage doubler instead of the diode bridge. It has only two
diodes instead of 4 so half of the voltage drop can be saved versus the 4 diode bridge.  The price to be payed for this
advantage is the need for using two electrolytic capacitors, see this link:
  http://www.augustica.com/full-wave-voltage-doubler-tripler-and-quadrupler-ezp-36  and I attached how it would
look simplified for your circuit.  C1 and C2 could be any value of 100 or 200 or 470 uF and higher,
working voltage should be at least 100V or higher.  If you use this doubler, all the 4 secondary coils could remain
connected in parallel of course.  In the voltage doubler, each diode could also be made of 2 or 3 fast diodes (UF4007)
connected in parallel to make the forward voltage drop even lower for each. 

Gyula

[SkyWatcher123]

Hi gyulasun, wow thanks, great ideas.
I'm testing the the 4 strands idea, 2 sets of 2 strands in parallel, then those in series, that is working far better.
Am able to lower the voltage to 24 volts input and the diminishing voltage usable for the oscillator, does not effect the charging nearly as much.
Yes, the high speed diodes is planned, only have two matching ones at the moment, so your full wave voltage doubler is something i can test.
I will keep the series/parallel secondaries in place, then lower the input voltage as far as i can, then use the voltage doubler and see how that works in comparison.
Thanks for all your valuable contributions gyulasun.
peace love light

Edit: i've been using air coil mode for these tests

[SkyWatcher123]

Hi all, Hi gyulasun, so far, with the 4 secondary strands in parallel and using the full wave voltage doubler, the output seems very good.

And the input is only 4 watts, 25 volts at .16 amps, though that will fluctuate as the charge battery changes in voltage.

Very impressed so far, will do a few proper load tests for watt hours to see.

I used for the voltage doubler, MUR460 diodes and 200v 470uF polarized capacitors.
peace love light

[SkyWatcher123]

Hi all, here is the latest circuit under testing.
peace love light

[gyulasun]

Hi Tyson,

Nice progress, there seems to be a few refinements could be done.

One such possibility is to reduce the number of turns for the 12 strands and use the ferrite cores to have
similar inductance the air core coils have now. Less wire length involves lower DC resistance and helps get
the desired increase in L/R time constant which reduces overall coil losses, see the link on the L/R time constant
in my reply #6, previous page.

Another possibility is using still a better choice for the 2 rectifier diodes. (I do not mention the transistor type
because it was addressed earlier).  On better diode choice I mean the followings.
Data sheet says the MUR460 has about 0.74V forward voltage at 100mA and 25°C (Figure 6 on Page 6,

https://www.onsemi.com/pub/Collateral/MUR420-D.PDF ) Should you have had a MUR420 type instead (200V, 4A)
the forward voltage drop would be about 0.64V at 100mA and 25°C (Figure 1 on Page 4) and for the two diodes
in the voltage doubler this means 200 mV less overall voltage drop at 100mA forward current.
A similar behaviour is found for the UF4003 diode (200V, 1A) versus the UF4007 (1000V, 1A), from data sheet
https://www.fairchildsemi.com/datasheets/UF/UF4001.pdf  Page 4 in Figure 2, forward voltage drop of UF4003 is
0.6V at 100mA while for UF4007 the drop is around 0.9V at 100mA.
You may think the 200V rated diodes prove to be underrated for the voltage spikes at the switch-off moments,
this can be true when the oscillator is run without any loading i.e. no 12V charge battery is connected.

Now have a look at this Schottky diode type SBR30300
https://www2.mouser.com/datasheet/2/115/SBR30300-464761.pdf this is a 300V, 2 x 15A diode and
it has 0.42V forward voltage drop at 100mA current and at 25°C (Figure 2, Page 3).
Because the two diodes are very closely matched, they can be connected in parallel to decrease
their forward voltage drop by a few percent (8-10%).
Unfortunately, such diode types are rarely found in common appliances one could scavenge them from.
In PC power supplies similar double Schottky diodes are surely used at the secondary side but their reverse
voltage ratings are around max 40-60V.

Keep up your your devoted work.

Gyula