Wiring separated PSU for Duet and Heated Bed

edurand

Hello eveyone,

I know the question has been asked several times.
To begin, thoses posts have been a great help and I would like to thanks all the contributors :

Powering a printer with 24V has many benefits especialy for 0.9 stepper motors but it come also with downside for running 12V heated bed and fans.
One a the solutions is to use two separate power supplies, a 12V and a 24V.

About my printer
Cartesian printer
24V Power supply
Multi-extrusion

Printer Parts

1x Duet wifi
1x Panel Due
1x Heated bed (E3D Square silicone 12V - 130W attached to an alu 210x210x3mm bed)
2x Extruder (E3D Bowden Titan extruder)
1x Hotend for dual extrusion (E3D Chimera with 2x 24V-30W heater cartridge)
1x Z-Probe (Piezo20 module)
6x Stepper motors :
-- 4x Wantai 42BYGHM809 0.9* Stepper Motors (Axis control)
-- 2x Motec MT-1703HSM168RE 0.9° Stepper Motors (Extruders)
2x Endstop (Hall-E endstop)
1x MKS Mosfet controller (to control the heated bed from the duet)
1x DC/DC converter step down (to power 12V fans from the main 24V)
3x Fans (Noctua 40x20mm : 2x for the hotend, 1x for cooling the duet)
2x PSU :
-- Meanwell PSU 24V 350W (UHP-350R-24)
-- Meanwell PSU 12V 200W (UHP-200R-12)

Can you give me a feedback on the schem bellow espesialy about :

the wiring of the 12V powering fan based on this comment :
https://forum.duet3d.com/topic/3389/12v-fans-on-24v-duet-wiring/13
“If all your fans are 12V, you should connect VOUT+ (the 12V from the regulator) to the middle pin (pin 2) of J3 (Fan Voltage Select) - DO NOT CONNECT ANYTHING to the other two pins (pins 1 and 3). Then connect your fans normally to the fan headers - they will all be 12V, whether switched or unswitched.”
the wiring of the emergency button (do I need a pull-up/down resistor?)

(download at full size here)

I hope this sketch will be a clear help to people in the same case of me

Thanks by advance for your help!

dc42

The emergency stop button should be connected to the two outer pins of the endstop connector.

You could omit the 12V step down converter if you common the negative outputs of the two power supplies and feed +12V from the bed heater power supply to the centre pin of the fan voltage selector block.

The Mosfet board isn't needed if you connect both PSU negative outputs to the negative VIN terminal of the Duet, and connect the bed heater between the positive output of the bed heater PSU and the BED- terminal of the Duet. If you do that then the bed heater LED will always be lit (brighter when the bed heater is turned on), but that won't do any harm.