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gzt

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  Reply # 751407 27-Jan-2013 09:09 Send private message

timmmay: Your scientifically magical way is called in parallel. Both power supplies positive terminals go to the positive terminal in the dust buster. In series the voltage increases, in parallel the current increases.

In practice that might not be a good idea with switch mode power supplies.

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  Reply # 751492 27-Jan-2013 14:22 Send private message

gzt:
timmmay: Your scientifically magical way is called in parallel. Both power supplies positive terminals go to the positive terminal in the dust buster. In series the voltage increases, in parallel the current increases.

In practice that might not be a good idea with switch mode power supplies.


I would avoid connecting any kind of power supply in series (for higher voltage) unless it is out of one instrument like a lab bench supply.  Parallel (for higher current) on the other hand is perfectly fine most of the time.

For normal isolated switch mode power supplies (not switch mode lighting supplies or regulated linear brick power supplies) it is perfectly fine to parallel them.  This is because all of them have a series diode on the output, and the voltage feedback is either done from the primary flyback pulses or with a high impedance secondary side voltage divider so if one is switched off while the other is on there is essentially no current flowing back into it.

Unregulated linear "bricks" are the same, but regulated ones are not and the end user seldom knows if it is regulated or not so safer not to do it with a brick.

AC supplies certainly do not parallel or you can actually get mains out (in reverse) if one is unplugged from the wall.

Some lighting switch mode supplies might not be sufficiently isolated, or have a boost regulator so you do not have proper blocking.




You can never have enough Volvos!


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