Kapanadze Cousin - DALLY FREE ENERGY

[Dog-One]

Thanks for the tips D1!

What capacity do you recommend in parallel with the power supply?

Surely not 3300uF like I initially used.  Take them way down.  For this, my rule of thumb is to keep the ripple Vpp down less than 10% of your intended rail voltage.  100uF seems to be gobs.  Run a lamp in series between the power supply and the inverter board as a pseudo fuse/resistor, then take a peek with the scope.  Using a current probe you should see the current ramp up when the MOSFET turns on, not a straight up square wave 40ns rise time.

You can also do similar tuning when the MOSFET turns off by finding a suitable capacitor that holds the output voltage for a short period, but when you do this you will end up needing a bit more sophisticated PWM where you can open up the dead time.  With the Mazilli circuit and your transistor bias limited, it's pretty easy to find a good combination.

HTH

[itsu]

Dog-one,

thanks for the info, i guess the core saturates like you said when using these coil, so i have to look for another set of coils.


Sky,

i see what you mean, so you  say that it is to be expected to see the double input voltage on the MOSFET's drains (25V -> 50V).
This however is not in agreement with when i change the both primaries of the transformer with  2 (middle fet) resistors, then it
just shows the single input voltage on the drains, see earlier screenshot.

Anyway, i did found another pair of coils i could use, they are connected to this common ground you mentioned.
I use this common ground now as the 24V input and with the both coil measuring 143uH it gives a clean (no ringing) square wave (60V) on the drains.
There is an output coil which gives me (after rectification) 135V dc out, so i will put that configuration on the PCB and take some pictures lateron.
I did add a 22K / 5W resistor across the 135V output
The diagram below shows where i have put the 24V now (common ground).


Jeg,

voltage rating of C24 is 250V, the R27 is a ½W resistor, it does not heat up, pictures and video later.


Regards Itsu

[skywalker66]

Sky,

i see what you mean, so you  say that it is to be expected to see the double input voltage on the MOSFET's drains (25V -> 50V).
This however is not in agreement with when i change the both primaries of the transformer with  2 (middle fet) resistors, then it
just shows the single input voltage on the drains, see earlier screenshot.

Anyway, i did found another pair of coils i could use, they are connected to this common ground you mentioned.
I use this common ground now as the 24V input and with the both coil measuring 143uH it gives a clean (no ringing) square wave (60V) on the drains.
There is an output coil which gives me (after rectification) 135V dc out, so i will put that configuration on the PCB and take some pictures lateron.
I did add a 22K / 5W resistor across the 135V output
The diagram below shows where i have put the 24V now (common ground).

Regards Itsu

Itsu,

it is correct what you say, but I'm also correct.
Your 2 resistors put in place of primaries for test purpose haven't mutual inductance.
Try to see that way: when one half primary is powered with 24V via mosfet, other half primary behave  as a secondary and receive 24V induced by first primary as the turn ratio between the two
primaries is 1:1, therefore, that 24V induced upon second half primary add up to 24V power supply
and from this your second mosfet drain voltage is rise up to 2 x Vps (24V) while first drain voltage is 0V (in conduction), and the same happens other half cycle.
Anyway, seems you managed to get the idea  and connect correctly and get desired 135Vdc at
output. I prefer to implement that kind of step up converter with tl494 or SG-whatever for output voltage control thru duty-cycle control or feedback control.

[itsu]

Skywalker,

ok, i got it, so it is expected behaviour, thanks for explaining.

After putting it all on a PCB, it again behaves differently  , so i have to troubleshoot again.......

Itsu

[itsu]

OK,  1 MOSFET source was not good connected to ground.

Below picture shows the PCB with the transformer in the lower left.
Input voltage is from 2x batteries in series, current for the whole PCB is about 90mA.
Output voltage across the (added) 22K resistor is 135V
Nothing is gotting hot.

The screenshot shows the drain signals.

The forum is very slow with me, so will upload a video later.

Thanks all,   regards Itsu