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Registered Member #8497
Joined: Tue Dec 04 2012, 06:24PM
Location:
Posts: 74
I've been content with my home-brewed 20W Boost Converter (~50% efficiency) for a while. I recently acquired a flyback transformer from an old TV.
I'm confused as to dealing with the bifilar winding. It is my understanding that you take a long wire, twist it, then wrap the 'twisted' wire about the primary.
Second - looking at Uzzor's 50W Charger, how do I deal with the wiring of the 47-250uH inductor to the primary?
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
Bifilar: it doesnt need to be twisted if you are using a core. A bifiliar arrangement is just a normal coil wound with 2 parallel wires. ...and of course 4 open ends.
"Deal with the wiring": use a solder iron at 320°C / 600°F...
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
..well in schematic it connects to the centertap of your primary...
you are aware that you dont use the bifilar coilat all. arent you? its just the easiest way to produce two equal , but seperated windings. you have to create your own center-tap by connecting the windings at one point.
Registered Member #8497
Joined: Tue Dec 04 2012, 06:24PM
Location:
Posts: 74
DerAlbi wrote ...
you are aware that you dont use the bifilar coilat all. arent you? its just the easiest way to produce two equal , but seperated windings. you have to create your own center-tap by connecting the windings at one point.
Sort of. The issue I'm having is with the picture of his windings. I notice that on the primary side, the center tap is not at a single point - it appears to run through the primary.
I also note that the orientation of the wrap is reversed from 'top and bottom'.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
If I understand you correctly, he's used two wires, one for each 'half' of the centre-tapped primary. The 'centre tap' is actually the centre terminal of the terminal block shown in the last photo. He's used three wire colours and joined them so he can tell which is which. I'd just use two wires myself.
He's twisted the wires together from the terminal block to the 'primary proper' in order to reduce stray inductance, etc.
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Bifilar Windings - Flybacks
