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I was advised that it would be possible to use an AC SSR to wire up a Mains Based heat bed. Any idea how one would do this with a RAMPs 1.4 board; Also, what do I hook a heated bed of this sort into?

1 Answer 1

A link to the bed you have/are buying would be very helpful. AC heated beds exist but are fairly uncommon.

As one of the answers in the question you linked notes, the heat bed is probably not actually intended to use the 110 VAC/220 VAC directly from the wall and instead needs either 12 VDC or 24 VDC. If the current it needs is less than 11 A, then it can be connected directly to port D8 on the RAMPS 1.4, where it will take power from a suitably powerful 12/24 VDC supply connected to the 11 A input on the board. A more powerful heater will need an external relay/MOSFET/etc. to control.

If you do, in fact, have an AC bed, you can connect a SSR like this to either D8 or D9 on the RAMPS (D10 could be used, but it would need a supply connected to the 11 A input) making sure the polarity is correct, as long as your RAMPS DC supply voltage is within the input range of the SSR. The linked one is 3–32 VDC, so almost any supply voltage compatible with the RAMPS will work. The AC outputs of the SSR should be connected in series between one side of the bed and the AC hot wire, with the AC neutral wire connected to the other side of the bed so most of the circuit isn't carrying high voltage when off. This video has some useful hints.

However, while an AC bed can get you faster heating, will let you use thinner wires, and avoids the need for having a big DC power supply, I would recommend against using a mains voltage bed if you don't know what you're doing—a great deal more care must be taken and there is a serious possibility of injury.

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