Running heatbed straight from the mainboard


I have a vertex printer and now that all my printers have heated beds, I want to upgrade the vertex too. I have everything around for the upgrade (better PSU, spare heatbed, thermistor,…) except for a Power expander and they are very expensive with shipping. I also don’t trust SSR’s, I know they have a massive voltage drop. So, can I run the heated bed straight from the main board?


[quote=“Andreas15”]So, can I run the heated bed straight from the main board?[/quote]Nope. The current is too high for the mainboard. A power expander is mandatory.
You can build yourself one. It’s quite easy and cheaper (check the [color=#408040]Wiki [/color]for parts and schematics).

In the schematics there are 4 poles for the heated bed, it just has 2 cables right? Why 4 poles?

I use a relay (coil, not ssr) with a protection diode, driven directly from the mainboard, to drive the heathbed (24V).
Not the smartest but effective and reliable so far (4-5 spools printed).