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Actually. I don't recommend those converters at all. I've used them before. Unreliable as they can go bad with weird modes of failure. Stick with a dedicated 12v power supply (like a computer power supply) and generate that 12v from scratch. It's cheaper and more reliable.

I've never had a problem but that's not to say it's the best practice either. I couldn't imagine fitting a meanwell 750w and a computer power supply in the frame.

I would second that recommendation against the converters. I have a great fondness for industrial supplies. For the 12V you shouldn't need more than 9A. If you were to buy say, a 10A 12V power supply, you could get a Meanwell DIN rail supply for ~42$. If you didn't buy a DIN rail one (They are much more compact, but have a good cost premium to them), you can get another Genuine Meanwell for ~25$.

2 meanwell on their sides, beside each other will fit inside bottom frame rails.

Sorry, homework got the better of me and I have not got the time to work on it. I did just realize I bought the wrong relays (I got the DC-AC ones, which won't work). Would something like thisdo the trick to isolate the heated bed from the duet?

bob64 wrote:Actually. I don't recommend those converters at all. I've used them before. Unreliable as they can go bad with weird modes of failure. Stick with a dedicated 12v power supply (like a computer power supply) and generate that 12v from scratch. It's cheaper and more reliable.

Oh man... why? Please explain those weird modes of failure.
I've just received a 240w 24v to 12v converter and was about to wire everything up.

TheRealRocketBurns wrote:Sorry, homework got the better of me and I have not got the time to work on it. I did just realize I bought the wrong relays (I got the DC-AC ones, which won't work). Would something like thisdo the trick to isolate the heated bed from the duet?

These should work, my concern is if the traces on the board are wide enough to carry the amperage required by the heat bed.
No harm in given it a try and letting us know how well this board works.

TheRealRocketBurns wrote:Sorry, homework got the better of me and I have not got the time to work on it. I did just realize I bought the wrong relays (I got the DC-AC ones, which won't work). Would something like thisdo the trick to isolate the heated bed from the duet?

The IRF540 mosfet used on that board is ancient, dirt cheap, and about the last thing I would choose for switching a high current bed heater. It needs more than 5V gate drive to turn it on fully and it has a very high on-resistance compared to modern MOSFETs.

If your bed heater draws more than 15A then I suggest you buy an Auber Instruments DC-DC SSR to switch it. If 15A or less then you can switch it directly from the Duet, but if it isn't a Duet WiFi then solder a piece of thick copper wire on the underside of the Duet between the VIN+ and Bed Heater+ terminals to help carry the current.

Tincho85 wrote:

bob64 wrote:Actually. I don't recommend those converters at all. I've used them before. Unreliable as they can go bad with weird modes of failure. Stick with a dedicated 12v power supply (like a computer power supply) and generate that 12v from scratch. It's cheaper and more reliable.

Oh man... why? Please explain those weird modes of failure.
I've just received a 240w 24v to 12v converter and was about to wire everything up.

voltage randomly dropping, causing printer to basically turn off. Especially fustrating when you're in the middle of a multi-day job and it acts like the printer "rebooted" itself randomly.
And eventually it degrades to random flickering of power. It actually corrupted the EEPROM on my rambo board.