Supply Controller (continued)

Nov 12, 2012 7 Replies
R

For schematic of my "controller" see

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. Some responders in the past indicated that the source had to be pulled down to ground for the dratted IR2118 to work properly. Note in my case i need the output to be adjustable from somewhere near ground (50V will do) to somewhere near supply (120V), and that voltage have little ripple (say under 10% or 10V - whichever is reasonable for supply to bottom of flyback in TV. As shown, i do not get an adjustable voltage, and it is fairly low.



Clues please to get this to work (or an alternate that is cheeep. Thanks.


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L

c/.

.

what are you trying to do, could you make a simple schematic?

-Lasse

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R

Please READ the first line..

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J

On a sunny day (Mon, 12 Nov 2012 12:57:35 -0800) it happened Robert Baer wrote in :

You need to read up on switcth mode design basics. At teh very basics you need to put a bit of charge into the output capacitor every cycle, that requires an inductor in series with the switch. This drawing you show makes no sense. You would also need a flyback diode in the simplest design.

  • --- switch --------L -------- | | in --- C load / \ | -- | | |

-------------------------------

There are many more ways and many configuration possible, yours is not one of them :-)

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L

/Misc/.

e

ere

low.

ep.

That is for you "controller", I mean a schematic of the system, the supplies, the load etc.

when you say bottom of flyback, I'm imagining you need a supply that can sink current?

-Lasse

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R

Full manual for the TV set, and extracted schematic, with selected info now added to

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. I have added a pulse transformer..the IR2118 is now driving its primary, and a 1K added from Vs (pin 6) to ground lets it work nicely. Still do not get adjustable range desired. The pulse transformer used is the Murata 78601/2C (500uH) and does not "transmit" the full width of the pulse:

|---\

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T

More inductance isn't the problem; you need one with a higher V.us flux rating.

In that particular series, they use Ferroxcube 3F3 cores, so a higher inductance will be consistent with higher flux, not just a higher permeability core.

Tim

-- Deep Friar: a very philos>> For schematic of my "controller" see

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.

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