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Old 13th January 2005, 01:24 PM   #1
arcom is offline arcom  Croatia
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Default Few SMPS issues

Hi all!

I've built the SMPS based on Rod Elliot's schematic. It worked like a charm until I've installed it in my car - output voltage was over 60V. So I decided to add voltage regulation (because I really don't want to re-wind the transformer AGAIN ) based on the schematic from Sergio, and it works well, except that the voltage is regulated only on positive rail, while the negative rail stays the same (few volts up/down). Is this normal, or not? (Note that I haven't tested it with high loads yet). Also, one side of the MOSFETs is cold as ice while the other one is warm. Why?

Thnx!
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Old 19th January 2005, 04:26 PM   #2
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Hi,

I will make new pcb for SMPS with feedback. (opto)
I did some calculations and this will be only test board.
I realy think that you should do more tests and else with your project...
__________________
Zeljko M
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Old 19th January 2005, 09:36 PM   #3
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Are your outputs loaded with a small resistance. I've built a couple switchers and had various anomalies when the outputs were unloaded.

I'm unfamiliar with the regulated circuit you mentioned but with the outputs loaded properly you should be able to adjust the output voltage by altering your pulse width which is supplied in the original scem.

Cheers
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Old 20th January 2005, 11:00 AM   #4
arcom is offline arcom  Croatia
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Hi,

everything is OK now
Those variations in voltage were beacause the SMPS was unloaded. When it's loaded, voltage is the same in both rails.

Also, heating problems are solved thanks to Zeljko!

Most of these problems were because I was lazy to isolate the MOSFETs from the heatsink
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Old 28th January 2005, 05:53 AM   #5
ssanmor is offline ssanmor  Spain
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As the writer of Rod Elliot's SMPS project, I am very happy to see that others are being able to build this circuit with success. When I started to investigate about it, it was very difficult for me to find information on this issue, so once I got it working I decided to share all that I have learned with the audio community. And what better place to do it than ESP?

I have designed an improved version of this supply, and it will be available to be purchased in a short time, I hope. It will come in the form of ready-built and tested modules. I will be selling a SMPS for home use and Class-D module amplifiers and some other "toys" I think will be very interesting to us audio fools.

Best regards and congratulations for your success!
Sergio
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Old 28th January 2005, 07:51 AM   #6
arcom is offline arcom  Croatia
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Hi!

I must congratulate you on writing that article! Excellent writing! It's been most helpful for me and a lot of people around the world, I believe.

Regards,
Marko
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Old 28th January 2005, 08:40 AM   #7
ssanmor is offline ssanmor  Spain
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A lot of thanks, arcom, but to be sincere, when I read the article now I find a lot of things that could be done to improve it (most of them found in the process of developing my recent designs).

I also think that some deeper explanations could be helpful for the newbie or the person interested on building it, product of the experience I have gained during these years designing DC/DC SMPS as well as Class-D amplifiers and off-line SMPS boards.

Perhaps I will review the article in a near future in collaboration with Rod, thanks to a fluid relationship we continue having, despite of being in just opposite sides of the world

Best regards,
Sergio
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Old 29th January 2005, 04:07 PM   #8
djQUAN is offline djQUAN  Philippines
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sergio, do you have a class D module that could run on +/-50V and drive 2 ohm loads easily? if so, inform me when you start selling them.
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Old 29th January 2005, 04:32 PM   #9
ssanmor is offline ssanmor  Spain
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We have a module that can be run up to +/-65v. It can drive 2 ohm loads without problem. For the current version of this module, perhaps it its not safe to run it at full excursion into 2 ohms continuously, as the output coil is dimensioned for 20A, but you can run it at about +/-45V, giving a power of about 450W.

We don't discard to make a higher powered version in the future, of course.

If you are an OEM, custom versions can be made to handle higher power.

As soon as we start selling them, I will keep you informed.

Best regards
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Old 30th January 2005, 12:55 PM   #10
djQUAN is offline djQUAN  Philippines
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I'm not an OEM. I just need a class D module to make a 500W mono (or maybe stereo) car amp. I'm already done with the 500W PSU with +/-50V, I'm still thinking about either using class D or a mono P68.
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