EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Mechatrommer on July 25, 2019, 12:56:41 am
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transformer selection part is always baffling, digikey cant provide with the spec i want or lack thereof. this is to step up 5Vdc input to ±12V to ±18V (bipolar Vdc) output. power rating is around 6-12W preferably small size such as 1x1x1cm unit, or probably more if science doesnt allow such small size. but i saw small unit such as this..
(https://i.ebayimg.com/images/g/~sQAAOSwbb9bOyxT/s-l300.jpg)
but usually they are getting power from mains 110-220Vac input. i need 5V input. the topology is something like in attached picture (transformer in the black lined box). 3 pins input centre tapped. centre pin will be Vdc+ input and both transformer end inputs will be alternatingly switched to create Vac effect. and then on the output, 2 pins only producing 12-18Vac, and later to be bridge rectified to get ±Vdc output. 3 pins centre tapped output also acceptable. toroidal type suggestion is also welcomed, and higher power transformer of this kind too are welcomed. any hint on transformer selection method, supplier or model number? thanks.
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Things like that tend to be custom-made for a particular purpose, so it might be hard to find one off the shelf. You may have more luck searching for a ready-made dc-to-dc converter module.
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Things like that tend to be custom-made for a particular purpose, so it might be hard to find one off the shelf. You may have more luck searching for a ready-made dc-to-dc converter module.
i have few dc-dc modules and ICs but i need isolation in this design, so needing a transformer. yes diy is the last resort in mind, i also already have few smps toroidal and H shape core stock, but winding coils takes time, esp if i want to make many of them, and i lack knowledge in making efficient transformer...
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That's not difficult if you go for a flyback converter with this transformer: 750314782
https://katalog.we-online.com/en/ctm/MID-POELT/S/750314782?m=n&sq=750314782&sp=https%3A%2F%2Fwww.we-online.com%2Fweb%2Fen%2Felectronic_components%2Fsearchpage_PBS.php%3Fsearch%3D750314782#vs_ct:2 (https://katalog.we-online.com/en/ctm/MID-POELT/S/750314782?m=n&sq=750314782&sp=https%3A%2F%2Fwww.we-online.com%2Fweb%2Fen%2Felectronic_components%2Fsearchpage_PBS.php%3Fsearch%3D750314782#vs_ct:2)
-This transformer has a 1:1 winding ratio between (5-3):(6-10):(7:9) which fit's your application.
-Switching frequency: the inductance between (3-5) is 37µH. The energy stored in one switching cycle is 0.5 x L x I². The total energy transferred is 0.5 x L x I² x F.
Regards
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Coilcraft (https://www.coilcraft.com/transsel_3-36.cfm) has several transformers, based on a chipset or app note.