Originally Posted by
AlienSteve
Hm. Yes, I think you can, if you use isolation diodes between the supplies. They may not be necessary, but it is a good idea. Use shottky diodes for low voltage drop.
Otherwise if one supply loses power, the output of the supply in parallel with it may cause a fault by supplying voltage into the unpowered supply's output. Of course if that happens and your circuit is drawing more than one supply can provide, you may end up with fireworks. Like having one battery die first in a series string and reverse charging that battery.
There is also the potential problem of slightly different output voltages causing one supply of a parallel set to coast while the other does all the work.
I have a vaguely similar situation. I have a bunch of 28Vac 3A transformers from old Apple Imagewriter II printers, I'm going to parallel them by having separate bridge rectifiers on each secondary, going to the same bank of smoothing capacitors. I will also be putting a smallish series resistor on each, between the separate bridge rectifiers and the common capacitor bank.
If I weren't so broke, I'd just buy a $20 transformer... 10A at 24Vac (about 36V rectified and filtered).