24v power with 12v converter

has anyone used a 24v power supply with a 12v converter with two leads from the psu-
-one going to a 12v converter and then to the 5A input
-then a second lead going straight to the 11A input. (after replacing the 11A fuse with a 12-15A )
wouldn't this provide 24V for the heat bed and 12V for everything else?

Edited 1 time(s). Last edit at 02/07/2017 02:43PM by Squareknot.

I use a buck converter to step down my 19.5v power supply to 12v. I don't see any reason why you couldn't just run two sets of wires from your PSU one straight to the board and the other to the converter, then the board. As long as your PSU has enough juice. I am not sure about mixing voltages though. I think the heated bed line is connected to the rest because you can power the heated bed through the 5a line if I am not mistaken. So, there is a possibilty the different voltages could run into each other somewhere and cause problems. I am not sure I am curious to see what someone else thinks though because I have been considering doing something similar.

I am pretty sure you could just hook it up separately though using a relay or MOSFET and just plug your thermistor into the RAMPS. That's my plan because I am planning to power my heated bed with mains voltage.

On a ramps the headed bed is on the 11amp rail. It is the only thing on the 11amp rail.

Thus putting 24volt in the 11amp (and making the fuse change) and putting 12v into the 5amp works fine.

As long as your converter can really handle the 5amps at 12v. It should work fine.

It depends on your 12V converter. There are many different types and you'd need one where GND isn't isolated or switched.
Do you have continuity between GND on the input and output side? Then it's OK.

Thanks to all for the help.
I think I will go with the Buck converter after switching out the fuses on the Ramps.
It appears that the only connection to the 5A and 11A side is the ground.
So, as long as I use a single source there shouldn't be any problems that I see.
The heat bed is a 24v, 360 watt unit, so that plus the remaining electronics may be too much for my power source, which is 24v 15A
I may need to upgrade that to higher Amp model.

You shouldn't feed such a beast of heatbed through the Ramps connectors. Some reports about molten connectors with standard bed heaters should give you a hint.
Better go for SSR relais.