switching PSU questions

[Finale]

I got two questions regarding generic LED power supplies.

1. Does connecting two switching power supplies in series only double the voltage, or also give you twice the amps you can use?

2. Does lowering the voltage with the trimpot (12V to 11V or 5V to 4V) allow you to draw more current from it, or is the rated current draw unaffected by that?

[absolom7691]

1. No. This will only double the voltage and may not even work if the power supplies are not designed for it. Likewise for parallel wired PSUs.

2. No. Switching power supplies are not rated in VA like transformers are. If it is rated at X amps, then you will only get X amps out of it.

[Finale]

Thank you.
I wanted to get two 4.5V PSUs together to reduce heat dissipation on my diodes. I already got a 12V PSU that can deliver enough current but the driver heatsinks get pretty hot when powering a P73 diode or a blue 3A diode.

[DanBarlow]

I suggest one of these or something similar:
http://www.dx.com/p/5a-constant-curr...7#.WECP9LIrL9Q
You feed your 12V into it and set the output to just enough for your diode driver to reach full power. Since it's a switching buck regulator, it will do the voltage/current tradeoff that you're looking for, up to 5 amps.
You can set both voltage and current limits, so it's slightly safer.
I use these to keep morons from blowing up my 3V drivers by putting 12V into them. They've worked great so far as wide-input DC to fixed DC converters.http://www.dx.com/p/5a-constant-curr...7#.WECP9LIrL9Q