Sorry I missed that, you might have been too subtle...




Even the ferrite transformer in an 800W offline SMPS is about 3x3x3", then you need input caps, output caps, input FET(s) and heatsinks, output rectifier(s) and heatsinks, fan, room for airflow and PCB and good 30A layout, etc.

It's going to be shoebox sized at least, if someone is good at squeezing stuff into small spaces.

I haven't seen a PC sized PSU good for 800W, but they might be that small now.

PC power supplies are now available in the 1200 and even 1600 watt range. But they definately do not meet the OP's size requirement or the 18 to 24 volt requirement.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817153145

 

PC power supplies are now available in the 1200 and even 1600 watt range. But they definately do not meet the OP's size requirement or the 18 to 24 volt requirement.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817153145

But it might because the OP only specified the FOOTPRINT size (3x3x5), not the height..... so I could make it as tall as I wanted.

Output voltage is easy to change just by changing the transformer turns ratio.

 

But it might because the OP only specified the FOOTPRINT size (3x3x5), not the height..... so I could make it as tall as I wanted.
...

Only if you "make it tall" in the 4th dimension?

It will become a "TARDIS" PSU.

 

But it might because the OP only specified the FOOTPRINT size (3x3x5), not the height..... so I could make it as tall as I wanted.

Output voltage is easy to change just by changing the transformer turns ratio.

You made me choke!

I said not available in 18 to 24 volt - because I was trying to find 'off-the-shelf' solutions to meet his, low cost objective. Now that you pointed out that he is willing to work in the 4th dimension, I realize 'low cost' is a relative term.

 

Only if you "make it tall" in the 4th dimension?

It will become a "TARDIS" PSU.

Yeah, somehow I was thinking it was 3" wide at each end and 9" long....... oh, well.