Thank you,

I was able to get it to -73 by elevating it. I'm printing a mount now that will allow me to stand it vertical and attach an 80mm fan.

Cheers

The bed I bought didn't have a thermistor, so I bought a separate one and I think the issue could also be the values being entered incorrectly. I'll have to measure the coefficients. But.. right now I have no time whatsoever (and sorry for the delayed response), I'll have to get back in a week or so.

@phaedrux I don't get what you're asking

@t3p3tony Hm so what would I do about the incredibly slow heating?

@t3p3tony If I don't have it on hand I'll just do it the previous way. Aliexpress takes at least 2 weeks to ship to me and I have everything else ready to go.

Edit: Sorry I completely misunderstood what you were saying. I googled around and couldn't find much either.

@djdemond 200W / 8.33A 24V heat bed, 350W / 14.6A 24V PSU

..Just realized, the mosfet is 12V. Or at least that's what the Amazon page says. But if I google for 24V mosfet I'm not getting any useful results.. Amazon page also claims it can handle 25A.

@djdemond Thank you! It works However heats extremely slow, which is possibly because I haven't run an autotune yet since using the previous 12v bed. I'm putting MGN12 rails on the Y axis tomorrow, so will install it properly and do the autotune etc then.

CTRL-in and Bed+/- is not the same thing. You can not connect a heated bed to CTRL-in. CTRL-in also does not have a polarity.

There is a DC IN+/-, Bed+/-, CTRL-In.

@djdemond

So just to confirm, I feed both the Bed VIN and Bed- to the Ctrl terminal? Are you sure VIN is needed?

Cheers

@djdemond Ah thanks!

So these have a 'ctrl in', a power+/- (dc in) and bed+/-

The ctrl in takes a 2 pin connector - do I use ctrl in for this?

I think I need a more detailed rundown if you can spare the time

From what you've said this is what I gather, but I'm still unsure about the ctrl in and BED- in particular

@djdemond said in 24v Heatbed with 12v everything else:

I'd like to throw in a second way, just in case the method outlined above doesn't suit you.

Get an external mosfet board (they are £5) . Optoisolated, they run from your bed heater output on the duet (12v is fine for this "signal") when the bed comes on the 12v signal switches the mosfet on the external board. Your 24v PSU is connected only to the external board, and through it the bed. I have a machine in this configuration.

Advantages:
Complete electrical isolation of 24v and 12v supplies.
No high current switching on your duet (I know compared to lesser boards they can do it but I like not switching so many amps on my most expensive component)

Disadvantages
None that I can think of (except spending £5).

These? https://www.amazon.com/gp/product/B06XY5HBFX/

I have four of them sitting in a box collecting dust.

I can think of one disadvantage, and that's having an extra board to account for when making an enclosure etc but that doesn't bother me.