Can you make an smps regulated by adding an lm317? - diyAudio
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Old 14th March 2013, 06:02 AM   #1
JZatopa is offline JZatopa  United States
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Default Can you make an smps regulated by adding an lm317?

So I was thinking about using an smps I have for a project but its not regulated. Is there any reason I couldn't put a voltage regulator like a lm317 after the smps?
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Old 14th March 2013, 06:11 AM   #2
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What are the voltage and current requirements of your project, and the output specs of the SMPS?
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Old 14th March 2013, 08:04 AM   #3
canvas is offline canvas  Taiwan
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Of course, you can put linear regulator after SMPS. Most 3C products have this design, e.g. every motherboard is powered by SMPS, and it still has linear regulators to power other chips.
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Old 14th March 2013, 04:21 PM   #4
luka is offline luka  Slovenia
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smps will not be regulated, if you add lm317. you willhave regulated output from LM, but that will be because LM, not smps
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Old 14th March 2013, 11:46 PM   #5
JZatopa is offline JZatopa  United States
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Luka does that really made a difference in any way?
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Old 15th March 2013, 12:24 AM   #6
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DJ, I asked for some specifics because you should remember that the LM317 requires a voltage drop of its own, 2-3 volts at best. Maybe a LDO regulator is a better choice. But generally speaking there's nothing to prevent use of a linear, buck or boost regulator to modify your SMPS output.
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Old 15th March 2013, 04:53 PM   #7
JZatopa is offline JZatopa  United States
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sofaspud I am acutally thinking about doing something a little crazy and using this SMPS to make an amp from some parts I have laying around. AFAIK the SMPS isn't regulated. If i get around to building the amp, i want to see if adding a regulator improves performance.
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Old 15th March 2013, 05:02 PM   #8
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That SMPS is about as unsuitable as a PSU could get for any non tube amp and is not suited at all for having an LM317 put after it, that SMPS gives off 280V DC on it's primary output rail!
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Old 15th March 2013, 05:19 PM   #9
JZatopa is offline JZatopa  United States
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I actually plan on using a HV lm317 circuit or similar HV regulator, i guess I should have been more clear.
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