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Thread: Topology for 50-200W SMPS for amplifier

  1. #1

    Topology for 50-200W SMPS for amplifier

    Hi All

    Intro: New user here. Limited experience with swithmode, but an EE in electronics and 10 years of electronics R&D. Know basic smps and have build class-D before.
    I have experience with EMC approval for electronics and I want to end up with a product that is reliable, safe and not a total EMC-disaster.
    Solid experience with safety, PCB's and system-design.

    The question: What type of switcmode would you recommend for use with a amplifier doing 200W peak music. (Bridge/parallel LM3886 on 8Ohm).
    I image specs could be something like:

    • Ac in 230V.
    • DC out +/- 25-35V. Maybe no need to regulate. Cannot peak above 80V total because the amp (LM3886) has a Vmax of 84V.
    • Average power 50W /peak power 200W


    I've been looking at either a version based on the IR2153:
    http://www.diysmps.com/forums/showth...orysgo2-design

    The oddball looks to be a flyback-type, but it max power is maybe too high and the advantages too low, when stuff like the IR2153 are becoming cheap and available.

    Or a self-switching type like:
    http://www.diysmps.com/forums/showthread.php?625-Easy-SMPS-for-everyone

    I would like to start with a Xformer from an old ATX-psu in order to get going with a safe X-former thats less likely to kill me, but I can wind a transformer if I need to.
    I have a big collection of ferrites.

    Thanks in advance.

    Kind regards TroelsM

  2. #2
    diysmps Senior Member Silvio's Avatar
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    Quote Originally Posted by TroelsM View Post
    Hi All

    Intro: New user here. Limited experience with swithmode, but an EE in electronics and 10 years of electronics R&D. Know basic smps and have build class-D before.
    I have experience with EMC approval for electronics and I want to end up with a product that is reliable, safe and not a total EMC-disaster.
    Solid experience with safety, PCB's and system-design.

    The question: What type of switcmode would you recommend for use with a amplifier doing 200W peak music. (Bridge/parallel LM3886 on 8Ohm).
    I image specs could be something like:

    • Ac in 230V.
    • DC out +/- 25-35V. Maybe no need to regulate. Cannot peak above 80V total because the amp (LM3886) has a Vmax of 84V.
    • Average power 50W /peak power 200W


    I've been looking at either a version based on the IR2153:
    http://www.diysmps.com/forums/showth...orysgo2-design

    The oddball looks to be a flyback-type, but it max power is maybe too high and the advantages too low, when stuff like the IR2153 are becoming cheap and available.

    Or a self-switching type like:
    http://www.diysmps.com/forums/showthread.php?625-Easy-SMPS-for-everyone

    I would like to start with a Xformer from an old ATX-psu in order to get going with a safe X-former thats less likely to kill me, but I can wind a transformer if I need to.
    I have a big collection of ferrites.

    Thanks in advance.

    Kind regards TroelsM
    Hello TroelsM Your best choice will be a half bridge driven with an IR2153 driving a couple of irf740. You can get plenty of power with an EI33 tafo from an old atx psu at around 60Khz. I don't know if you are capable of designing a trafo but I can help you. I have just finished a prototype of this kind and it is rather versatile as it can take various different oscillators as they can be fitted in a separate pin header, It also can have different protection sensing, like current tafo or capacitve coupling, mine is fitted with a current limiter and had trimmed it and works very good. Mine uses an etd 39 and can peak 700 watts however you can alter a bit the pcb to suit your trafo. If you want to take a look you can see some pics and also there is a video of winding the transformer on youtube.

    Link http://www.diysmps.com/forums/showth...p?894-Uni-SMPS

    link https://www.youtube.com/watch?v=_K3ixhcTYFg

    regards

    Silvio

  3. #3
    Hi Silvio.

    Thanks for the feedback. The Uni-SMPS looks vary capable and simple enough.

    I would prefer a smaller solution, but I guess it can be scaled down. Will you be releasing schematics?

    TroelsM

  4. #4
    diysmps Senior Member Silvio's Avatar
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    Quote Originally Posted by TroelsM View Post
    Hi Silvio.

    Thanks for the feedback. The Uni-SMPS looks vary capable and simple enough.

    I would prefer a smaller solution, but I guess it can be scaled down. Will you be releasing schematics?

    TroelsM
    Quote Originally Posted by TroelsM View Post
    Hi Silvio.

    Thanks for the feedback. The Uni-SMPS looks vary capable and simple enough.

    I would prefer a smaller solution, but I guess it can be scaled down. Will you be releasing schematics?

    TroelsM
    Yes why not I will post the pdf of the schematic and a couple of pics showing wave forms no load and full load, in my case no snubber was needed as the trafo has very good coupling.


    Attachment 6127Attachment 6128

    Attachment 6129
    Last edited by Silvio; 04-25-2017 at 10:22 PM.

  5. #5
    Hi Silvio.

    Sorry, I cannot see the attachment.

    Kind regards TroelsM

  6. #6
    diysmps Senior Member Silvio's Avatar
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    Quote Originally Posted by TroelsM View Post
    Hi Silvio.

    Sorry, I cannot see the attachment.

    Kind regards TroelsM
    Ok no problem I will re-post them again

    IMG_0576.jpgIMG_0575.jpg

    SMPS 700 Scematic.pdf

    I noticed that there is a small mistake in the schematic. The gate to source resistor of the low side fet should be tied between gate to ground and not at the center where it is.

    regards

    Silvio
    Last edited by Silvio; 04-26-2017 at 05:58 PM.

  7. #7
    Quote Originally Posted by Silvio View Post
    Ok no problem I will re-post them again

    IMG_0576.jpgIMG_0575.jpg

    SMPS 700 Scematic.pdf

    I noticed that there is a small mistake in the schematic. The gate to source resistor of the low side fet should be tied between gate to ground and not at the center where it is.

    regards

    Silvio
    Hi Silvio,

    With your schematic, Can I increase output voltage to +/- 65V or 70V? And can you share your PCB?
    Thanks and Best regards,
    ThaiKy

  8. #8
    diysmps Senior Member Silvio's Avatar
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    Quote Originally Posted by ThaiKy View Post
    Hi Silvio,

    With your schematic, Can I increase output voltage to +/- 65V or 70V? And can you share your PCB?
    Thanks and Best regards,
    ThaiKy
    Yes you can you have to increase the number of turns of the secondary windings accordingly.

    WARNING Please be careful when winding your own transformer as if the primary leaks with the secondary winding it will kill you.

    There is a blog post on this web site which will guide you how to wind transformers for smps. Please download the pdf file and read it. There is also a video on Youtube called winding small transformers for smps. See the video so that you will know better what to do.

    The PDF file for building the smps is already there. the tread is called (IR2153 350 watt RMS Audio SMPS with current limiter --based on Borysgo2 design)

  9. #9
    Quote Originally Posted by Silvio View Post
    Yes you can you have to increase the number of turns of the secondary windings accordingly.

    WARNING Please be careful when winding your own transformer as if the primary leaks with the secondary winding it will kill you.

    There is a blog post on this web site which will guide you how to wind transformers for smps. Please download the pdf file and read it. There is also a video on Youtube called winding small transformers for smps. See the video so that you will know better what to do.

    The PDF file for building the smps is already there. the tread is called (IR2153 350 watt RMS Audio SMPS with current limiter --based on Borysgo2 design)
    Hi Silvio,

    Thank you for you advice. I will be careful when make smps.

    ThaiKy.

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