Can I use a "tacho fan" (either with our without tacho mode)
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David /Roland
I think I may have found to a possible solution to the heat creep issues that the 5 colour Diamond has by adapting the mount to take a 60mm fan rather than a 50mm fan. This will allow me to get a much higher flow rate at a higher static pressure too. I've managed to source this beast https://www.mouser.co.uk/ProductDetail/Sanyo-Denki/9GV0624P1G031/?qs=sGAEpiMZZMt9MS9kROxCwxJGgTye%252bJ04nSt5MfM4j3w%3d which at around 80 cfm is about 4 times the airflow of what RepRap.me recommend. The thing is, it's a tacho fan with sense and control wires. Can I use it with the Duet? If so, how do I wire it? I don't care about varying the speed - happy for it to run flat out. Oh, and it's 33W, 1.4A but I guess that won't be an issue?
Cheers
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I think it's possible, see http://pcbheaven.com/wikipages/How_PC_Fans_Work/
Added and corrected voltage for PWM: If it doesn't rotate just being supplied with 24V/GND at red/black wires you would connect PWM wire (brown) to 5V separate wire . PWM is a control logic signal with 5.25V max level but I think 3.3V will do the job too. -
OK so a quick search of this forum (why didn't I think to do that before) has revealed what I think is the answer but just want to check. So Red and Black wires to 24v supply, control (Brown) to Fan - and ignore the sensor (Yellow). Yes or no?
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If you need PWM control then yes connect brown to Fan. If constant driving of the fan is OK then you can leave brown free. Sensor doesn't have matter anyway.
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If you use the control wire then I recommend you connect a 1N4148 or similar diode in series with the control wire, cathode to Duet fan output and anode to fan control wire. Increase the F parameter in the M106 command for that fan to 25000.
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@dc42: just out of curiosity what is the diode for? Couldn't nMOS switch withstand 24V?
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If you use the control wire then I recommend you connect a 1N4148 or similar diode in series with the control wire, cathode to Duet fan output and anode to fan control wire. Increase the F parameter in the M106 command for that fan to 25000.
Thanks David. You said "if you use the control wire" so does that mean I can ignore that too and connect just red and black to the fan connector as normal? Also the spec doesn't say whether it's brushed or brushless. I seem to recall reading something somewhere about using a flyback diode? Do I need to do that too and if so, what diode and where. Board is Duet Ethernet (plus Duex5) BTW
Cheers
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Yes you can just connect red and black as normal and leave the other 2 wires unconnected. No need for a flyback diode because these fans are always brushless - and all production Duet Ethernets have flyback diodes built-in anyway.
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Yes you can just connect red and black as normal and leave the other 2 wires unconnected. No need for a flyback diode because these fans are always brushless - and all production Duet Ethernets have flyback diodes built-in anyway.
Brill !. That's what I like - nice and simple.
