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  1. Replies
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    Can you post your actual schematic? I am...

    Can you post your actual schematic?

    I am seeing the MOSFET take a very long time to switch, about 1.5 usec
    I would guess problems with the driver, looks like turn ON time is too slow, or way too...
  2. Yes, the ATX PSU transformers will work...

    Yes, the ATX PSU transformers will work backwards. I've also used junk AC inverter (i.e. 12V to 240VAC) transformers. It depends on the voltage and power you are wanting.
    Looking at your design, R10...
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    Just an update- I found part of the overheating...

    Just an update- I found part of the overheating is due to instability. At certain loads and input voltages, the freq. is all over the place.
    I optimized for 11-16VDC in, and 5V out up to 2.5A output...
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    5.1V or 5.2V is nice to have - some USB chargers...

    5.1V or 5.2V is nice to have - some USB chargers output 5.1V; USB's voltage spec is 5.0V +/- 5% (4.75V to 5.25V) so I think the extra 0.1V compensates for the voltage drop across the USB...
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    That IR camera is a Flir E30...

    That IR camera is a Flir E30, I use at work to identify hot spots on circuit boards for UL/CSA tests on my designs. IR cameras are expensive and low-resolution. Our budget was around $2,200 and that...
  6. Replies
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    This sound very similar to a gas-laser SMPS. I...

    This sound very similar to a gas-laser SMPS. I built one (although push-pull square wave) and used teflon stranded wire for the secondary and ran it into a voltage-tripler to get DC.

    I would look...
  7. Replies
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    DiyAudio (http://www.diyaudio.com/) is a huge...

    DiyAudio is a huge site, a wealth of information there, millions of posts:
    Members: 249,404
    Threads: 218,224
    Posts: 3,296,462

    If an owner can make a living from it, great! But I'm sure it's a...
  8. Replies
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    Chinese LM2596 step-down converter modules

    I needed a high-current car USB charger 5V at 2.1A for my iPad, smartphone etc. Chinese LM2596 3A step-down converter modules are for sale on eBay and DX for $1.50 to $4.40 (which is cheaper than I...
  9. the IRAUDPS1 reference design

    Be careful with the IRAUDPS1 reference design; a big difference between a technical paper and something for mass production.
    Some of the numbers are off. Example: It's a 490W output design (+/-35VDC...
  10. Replies
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    Alternate mosfets

    Yes IRF3205 will work, a stronger mosfet. I have seen a pair used at 375W, so no need to run four. I would lower the gate drive resistor to 10 ohms. I think the IRF3206 looks good too.

    IRLB3036:...
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    The bill-of-materials is missing a bunch of part...

    The bill-of-materials is missing a bunch of part values, many are "???"
  12. Aluminum heatsink extrusions

    I can't find any aluminum extrusions like car amp manufacturers use. Even then, they are small heatsinks, and would run hot, for say a 75-125Wx2 class AB amp.

    I best like the aluminum heatsink...
  13. Replies
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    Other than the "ChongX" electrolytic capacitor,...

    Other than the "ChongX" electrolytic capacitor, everything looks really good and I compliment you on the build so far :UP: even though it's torturing you... I would be suspicious of low cost...
  14. Replies
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    You have to heat etchant (ammonium persulphate,...

    You have to heat etchant (ammonium persulphate, blue stuff) to 40-60C or it does pretty much nothing; ferric chloride (brown stuff) works OK at room temp. But you also have to rock the etchant (stir)...
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    Hi Alex, that looks really good, it's a good amp...

    Hi Alex, that looks really good, it's a good amp :cool: The GU50's look strange with metal ring on the top, what is it for? How much is B+? Where did you get the transformers from. I use Hammond,...
  16. Replies
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    Some ideas on your pcb layout... You will need...

    Some ideas on your pcb layout...
    You will need heatsinks for the mosfets and rectifiers. Like ones from a junked ATX PSU? Bare TO-220 can dissipate about 1W for 88C.
    Then think about how you will...
  17. Replies
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    Getting prototype pcb's made

    I've found BatchPCB is cheap, compared to other PCB houses.
    $10 setup fee, 2 layer - $2.50/sq. inch, 4 layer - $8.00/sq. inch.
    Cons: they take weeks for them to arrive, fixed at 1oz copper and...
  18. Replies
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    Litz wire here looks good: Surplus Sales of...

    Litz wire here looks good: Surplus Sales of Nebraska

    This IEEE paper uses ordinary stranded wire in place of litz wire - but they first stripped the wire and oxidized all the copper strands (200C...
  19. Replies
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    Hurrah! I think your no-load current is fine,...

    Hurrah!
    I think your no-load current is fine, you lose a few watts in the transformer core. If your SMPS is 90% efficient, at 250W out there's 25W of losses.
    You can lower flux in the core (more...
  20. Car audio amp PCB - need some ideas for the mechanical and heatsinks

    I'm doing a car audio amp PCB and need some ideas for the mechanical. Best configuration for where to put the SMPS and amp and output transistors? It's 2ch or 4ch x 120W class AB.

    Usually it's an...
  21. Replies
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    I would try to narrow it down a bit. First get...

    I would try to narrow it down a bit.

    First get the gate-drive fixed up - it should be more than 10V swing. You loose about 2V in the 3525 and another 1V in the buffer. Is it 5V still? Coming out...
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    Why are you running such high voltage for a 10HP...

    Why are you running such high voltage for a 10HP motor? Prius went from 274V to 202V, Chevy Volt is 300V battery pack. Although current and I^2R losses go down at higher V, then you get losses in the...
  23. Replies
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    Although the SG3525 can direct drive MOSFETs, I...

    Although the SG3525 can direct drive MOSFETs, I find you can drive one pair of small MOSFETs (15V and <2,000pF) but the very low RDS on MOSFETS have too much gate capacitance (>10,000pF). Since there...
  24. Replies
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    Just a quick look at your pcb and it looks good...

    Just a quick look at your pcb and it looks good :) but maybe a few small changes.
    I would have a trimpot to adjust duty cycle, in case you need less V or want to add regulation.
    The driver...
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    If you are driving only one winding (1/2 of...

    If you are driving only one winding (1/2 of push-pull) with no secondary load, the transformer core will magnetize and saturate. Each pulse set, you need to reset the core's flux by doing the second...
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