Remapping fan to heater output
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Yesterday night, with a friend at our hackerspace, I measured the in-rush current of my Berd air pump.
- without thermistor, it reaches 7A (see https://www.logre.eu/piwigo/picture.php?/187)
- with thermistor, it only reaches 4A (see https://www.logre.eu/piwigo/picture.php?/186)
I used this thermistor: https://fr.farnell.com/epcos/b57237s0259m000/thermistance-ctn/dp/9754156
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I juste tried to remap my tool fan to a heater output, but it does not work:
M106 P3 A0 S0 I0 F500 H-1
Error: M106: Logical pin H0 is not available to use for fan 3All heaters logical pins fail.
Fans logical pins (20-) work fine.
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Did you disable heater 3 first, the same as if you were using M42 or M280 to control it?
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No, I didn't... Thanks!
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Ok, it works. Except that at startup, the pump is at full speed. My config is:
M307 H1 A-1 C-1 D-1
M106 P1 A1 F25000 H-1On the GUI, only Fan1 cursor is at 100%; Tool Fan cursor is at 0. Once the tool is selected, Tool Fan is correctly linked to Fan1.
Any idea what's going on?
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https://duet3d.dozuki.com/Wiki/GCode#Section_M106_Fan_On
Can you use the S param to set a low speed to start?
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Yep, it works. Thanks!
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Fan 1 defaults to being on at power up, because it's intended to be used as the heatsink cooling fan, and you might have rebooted the Duet while the hot end was hot (I certainly do that when developing firmware!).
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No, it starts even with hotend cold. And it has thermostatic off (H-1)...
I'm using Fan 2 for heatsink cooling (water pump, in fact); I will switch both to see.
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@fma said in Remapping fan to heater output:
No, it starts even with hotend cold. And it has thermostatic off (H-1)...
Yes, it would do that. If you cancel thermostatic mode, you also need to turn the fan off in the M106 command.
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Hi @dc42, If we are using a brushed air pump on a heater output, do we still need the diode and if our current is below the mosfet rated current, do we need the thermistor in series with the pump?
Regards,
Sam -
@samlogan87 said in Remapping fan to heater output:
Hi @dc42, If we are using a brushed air pump on a heater output, do we still need the diode and if our current is below the mosfet rated current, do we need the thermistor in series with the pump?
You need the flyback diode but not the thermistor.