I have two 6V 1.2A power supplies, and I'd like to parallel them to get ~ 2 .4A. Can you safely do that? These are identical manufacture wall warts, an d I don't know anything about them other than the ratings and that it claim s to be a switcher on the label.
The short answer is no. The long answer follows.
You can design parallel power supplies, but taking two off the shelf won't really work well. Because power supplies generally only source current, often you can parallel them, but the results aren't all that predictable.
To parallel supplies, you really need to "coordinate" the controllers, otherwise the controller with the lowest voltage reference will end up doing all the work.
In the simplest terms, think of a switcher working like this. The voltage sags, so the controller tells the supply to dump some current, raising the voltage. So the one with the lowest trip point commands all the hits. With continuous conduction, it is more complicated than that.
Some of these computer power supplies use components in parallel to save money. That is, if you stock magnetics suitable to build a 600 watt power supply and you want to sell a few 1000 watt power supplies, you can use multiple components of the lower wattage power supply, but the control loop is more complex.
There's a way but it isn't perfect. You would have to load each of them and measure how well they regulate. Then choose ballast resistors to get them to share the load. The closer they are, the lower value resistors you can u se, the farther apart, the higher. It could get to the point where the resi stors have to be so high you can't get near the full current, and regulatio n will suck.
You are almost better off putting them in series and using a buck convertor . By the time you do that you could've just bought an adequate power supply .
if they're mot regulated it's probably work ok. otherwise probably not.
-- umop apisdn
2.4A. Can you safely do that? These are identical manufacture wall warts, and I don't know anything about them other than the ratings and that it cla ims to be a switcher on the label.
Probably. Odds are if there's a slight V_out difference that one will deliv er upto 1.2A then current limit, then the 2nd one will kick in getting you
2.4A. Probably.NT
It might work; one could current limit and the other one supply the rest of the load current. Try it; nothing bad is likely to happen.
Some of these wart supplies current limit by shutting down for a while and retrying. Those types won't work in parallel.
You could also get a 6V 3A wart cheap.
-- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Try it, with a fire extinguisher at hand.
Unless they are PERFECTLY matched, one will try to supply all the current and the other will pretty much shut down.
You could try "ballast" resistors from each to a common output, with a resulting voltage drop. ...Jim Thompson
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I love to cook with wine. Sometimes I even put it in the food.
Life is never so simple... I bench checked the power supplies, and they're actually all 5.45V (same reading loaded and unloaded), not 6V as stated on the label. There's also a "5V 3A" labeled power supply from the same compan y that measures out at 5.45V.
These are for LED Christmas lights, and I'm unsure that boosting the voltag e from 5.5V to 6V using a standard wall wart is a good idea. I suppose I co uld take a 6V wall wart and put a standard silicon diode in front of it, an d that should yield pretty close to what this 5.45V supply is putting out.
If you run the LED string from one 1.5A 5.45 or 6 volt supply, it's likely to look just fine. The supply may current limit and cost you a little brightness. No harm done. Again, try it. Nothing bad is likely to happen.
If it blinks, you have a shutdown/retry type supply, which wouldn't look good on a christmas tree.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
re actually all 5.45V (same reading loaded and unloaded), not 6V as stated on the label. There's also a "5V 3A" labeled power supply from the same com pany that measures out at 5.45V.
tage from 5.5V to 6V using a standard wall wart is a good idea. I suppose I could take a 6V wall wart and put a standard silicon diode in front of it, and that should yield pretty close to what this 5.45V supply is putting ou t.
some people might like it :)
NT
I don't suppose you've considered the obvious... running half the lights from each supply???
They GE G35 'Color Effects' bulbs and have a digital logic (microcontroller ?) on each bulb. That's why I'm concerned about what might happen if there' s too much supply. Could be they chose 5.5V specifically to maximize bright ness without destroying the logic.
I suppose I should dissect one of the bulbs and see what kind of controller it is using and/or whether there is on-board regulation.
er?) on each bulb. That's why I'm concerned about what might happen if ther e's too much supply. Could be they chose 5.5V specifically to maximize brig htness without destroying the logic.
Yep. I forget what psus you have, but diodes or schottky diodes can always drop some. No, they dont drop 0.6v at rated i.
er it is using and/or whether there is on-board regulation.
NT
plus or minus ten percent eh!
probably close enough then.
-- umop apisdn
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