Thermostatic fans

  • M308 S0 P"bed_temp" Y"thermistor" T100000 B4138 R4700 ; bed thermistor V3
    M308 S1 P"e0_temp" Y"thermistor" T100000 B4138 R4700 ; e0 temp sensor V3
    M308 S2 P"mcu-temp" Y"mcu-temp" A"Duet"
    M308 S3 P"drivers" Y"drivers" A"Drivers"
    M950 H0 C"bed_heat" T0 ; heater 0 uses the bed_heat pin, sensor 0
    M950 H1 C"e0_heat" T1 ; heater 1 uses the e0_heat pin and sensor 1
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    M143 H1 S340 ; Set temperature limit for heater 1 to 300C
    ; RRF V3
    M307 H0 A46.4 C211.7 D14.8 S1.00 V24.6 B0 ; bed V3
    M307 H1 A230.7 C115.6 D4.9 S0.90 V23.9 B0 ;; V3 e3d 24v hotend

    ; Fans
    M950 F0 C"fan0"
    M950 F1 C"fan1" Q500 T1
    M950 F2 C"fan2+exp.pb6" T1 Q500
    M106 P0 H-1 C"Parts Cooling"
    M106 P1 R1 H1 T45 C"Hotend Cooling"
    M106 P2 H2:3 T25 C"Board Cooling"

    I have 3 fans as shown above. The Hotend cooling fan is thermostatically controlled and works as it should. F2 I'm attempting to make thermostatically controlled and nothing I do seems to work with it. It's always on running at about 2200rpm. The only differance between F1 and F2 is that F2 is a 12v fan running from a 24-12v converter and F1 is a 24v fan.

  • PWM on fans is performed by switching GROUND. How is the converter wired?

  • it's wired to the fan2 terminals on the board. I tried without the buck converter and reducing the available speed but of course that just blew up the fan.

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