Ill make it easy on you. Solid state so you don't hear clicking.

Yeeco® 30A High Current 12V Contactor relay Switch Power Switch DC power Switching Control Board Control Module electrical relay switches for Cooler Heater Refit Water Heater Control

https://www.amazon.com/dp/B00MKWACVI/ref=cm_sw_r_apa_dXp4zbRYT8YMA

Yellow = +12 Black = Gnd I would also recommend using the following relay and power the heated bed from the relay using the printrboard heated bed output to trigger the relay. https://www.amazon.com/gp/product/B00MKWACVI/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I find that 80 C is the max the printrboard can get my Simple Metal to heat and that takes a long time and is in an enclosure. I have the relay and am in the process of making a mount for it and connecting it to the 24 pin power connector on my ATX power supply so that I get access to the second rail. The relay was recommended to me in another post.

Be careful with the polarity to the Printrboard the earlier 4 pin versions were opposite the 6 pin. The reason then went to six pins is the amps were needed.

OK, I'm sold I think :)

I guess you would wire it 12V --> MiniRambo --> Bed output --> the "on" switch for the relay... and then a separate high power wire to the relay, and then out to the bed?

A relay like this? (rated for 12V/70A) http://www.microcenter.com/product/422408/Relay_SPST-NO_70A_12VDC_0250in_Quick_Connect_Terminals_w-Mounting_Flange

or I guess this also works https://www.amazon.com/gp/product/B00MKWACVI?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00