Connecting High power 12V fan to Duet 3 6HC

dc42

@war4peace the simplest option is probably to use a DC-DC converter connected to the VIN terminals to convert the 24V Vin down to 12V. Then connect the fan to one of the 4-pin OUT connectors as normal, except that the fan positive wire should be connected to the 12V output of the DC-DC converter instead of to the VIN pin on the 4-pin OUT port.

Another way is to remove the OUT voltage select jumper next to the 4-pin OUT ports, and feed the 12V output of the DC-DC converter to the centre pin of that 3-pin jumper block. Then all the 4-pin OUT ports will operate at 12V. Caution, make sure that the connection to the centre pin of the jumper block isn't liable to come loose.

feeshfeud

@war4peace They are electrically in parallel, but plumbed in series. So each receives identical an PWM signal from the board for RPM and iirc 18V from the independent supply. Flow is in series, doubling the pump head to better deal with narrowish tubing and ~6ft of static head on startup. Sorry if that wasn't clear, didn't want to confuse the point about wiring an external supply. Since they are plumbed in series I don't really want independent speed control, and tach isn't overly important as I tend to just set them to ~85% max at boot and leave them there[0].

Connections in detail: The board connection (Duet3 mainboard) is one of the 4 pin fan headers (e.g. out 4), via a fan extension cable where I've snipped the power/grnd wires (leaving PWM/tach). That extension then connects to a 4 pin 'fan splitter' y cable which connects to both pump motors' stock signal connectors.

For power I just rigged a 2 x molex (standard ATX / computer 4-pin) 'Y' cable to a ground/pwr pair of leads. The power / ground wires are soldered to a (comically oversized) diode which I bent into a U shape and inserted into a screw terminal type 'universal' laptop power adapter (DC barrel to 2 x screw terminal connector). Not sure the diode is strictly necessary, but it was an excuse to break out the soldering iron and it cost all of 40 cents on digikey.

Doing a single fan/pump should be the same without the y-splits.

[0] I'm not in front of my machine right now, so I might be misremembering and the pumps might just not have a tach signal -- which would obviously explain why it doesn't work.

war4peace

@feeshfeud said in Connecting High power 12V fan to Duet 3 6HC:

Connections in detail: The board connection (Duet3 mainboard) is one of the 4 pin fan headers (e.g. out 4), via a fan extension cable where I've snipped the power/grnd wires (leaving PWM/tach). That extension then connects to a 4 pin 'fan splitter' y cable which connects to both pump motors' stock signal connectors.

[0] I'm not in front of my machine right now, so I might be misremembering and the pumps might just not have a tach signal -- which would obviously explain why it doesn't work.

That might be why the tach signal isn't working. I (used to) have two pumps as well (in my PC), and I used one tach signal from each pump, connected to separate tach pins.
You can use one pump as "master" with the tach signal, and from the other use just the PWM wire.

@dc42 thank you for your response. I can get a Mean Well DDR-60G-12 which provides more than enough power. Just to be extra-sure, the DC-DC converter should only provide the positive wire (one wire in total), or both positive and ground?

dc42

@war4peace said in Connecting High power 12V fan to Duet 3 6HC:

Just to be extra-sure, the DC-DC converter should only provide the positive wire (one wire in total), or both positive and ground?

Low cost C-DC converters normally have a common ground between input and output. If you use a separate 12V PSU, connect the ground of that PSU to Duet ground at the VIN terminal.

deckingman

@war4peace 24V DC blowers aren't hard to find.

Here is one example https://www.mouser.co.uk/ProductDetail/Sanyo-Denki/9BMB24P2K01?qs=t9Lg9qrXjEyExan66RDEjA%3D%3D. It's 56.9 CFM so plenty powerful (double what you think you need). Rated at 38.8 W /24V so only about 1.6 Amps. Mouser UK are showing 196 in stock for a mere £15.62 each.

Here is another with tacho output if that's of interest https://www.mouser.co.uk/ProductDetail/Sanyo-Denki/9BMB24P2G01?qs=t9Lg9qrXjEyBtgiNnUKzhA%3D%3D. Slightly lower rating at 47CFM but it's only rated at 19W so about 0.8Amps. Mouser UK stock level is 94 at a cost of £19.57 each.

There are probably many more but I didn't look beyond the first page of 15 which matched the 24V criteria. I don;t know what part of the world you are in but Mouser are a global business so likely have site in your part of the world. If not try other vendors and look for Sanyo Denki fans.

war4peace

@deckingman

Problem number one:
Shipping Alert: Product available only to OEM/EMS and design business customers. Product is not shipped to consumers in the EU.

Problem number two: it's not the right size. I need a 7530 fan, not a 9533 fan.
Problem number three: it's heavier than the 12V 7530 fan. 190 grams versus 140 grams.
Problem number four: has less air pressure than the 12V fan, air pressure takes precedence.
Problem number five: the 7530 fan I had linked was successfully tested in 3D printing, as a matter of fact it was used to cool the Benchy in the Speedboat challenge bed slinger world record (https://www.youtube.com/watch?v=3rQoG3aUKMI). The fans you have linked have not been tested.

I'd rather invest in a 25 bucks 24V-12V converter, rather than experiment with something that's bigger, heavier, less performing and harder to obtain, just because it's 24V.

Appreciate the recommendation, but it's not what I am looking for.

@dc42 thank you, I will test, check and install as recommended.

deckingman

@war4peace They were just the first two 24V blowers I came across out of 15 pages of results. Sorry that I wasted my time trying to save you time and money - I surely won't be doing it again. Good luck.

war4peace

@deckingman I'm afraid there is some misunderstanding here.
The topic is not about saving time and money, there's plenty of either. It's about performance in a small package, with specific requirements. I appreciate you trying to help, it was just not what I needed, that's all

war4peace

Sorry about the necro, but I wanted to continue this topic to keep things consistent.
I have managed to buy a better fan, the Delta PFB0412EN-E, here's the specifications document.
As mentioned before, I have a Duet 3 6HC which has three 4-pin PWM fan headers.
The fan is powered using a DC/DC converter (Mean Well DDR-60G-12) which is itself powered from the same PSU as the one powering the Duet (Mean Well NDR-240-24).

I have received a very informative reply from @dc42 above. Based on it, I have devised the following, beautifully hand-painted circuitry.
I'd like to confirm this is how hardware is supposed to be connected... I'm not an electronics expert...

Thank you in advance for your replies!

dc42

@war4peace the PWM fan header connections look wrong to me. The pins are labelled on the underside of the board in order: GND, V_OUTLC1, OUTn_TACHO, OUTn_NEG. The corresponding fan wires should be: black, none, yellow, blue. Connect the fan red wire to the +12V output as your diagram shows.

Make sure you have a jumper on the VOUTLC jumper block that feeds the PWM fan outputs, even if you are not powering any fans from it, otherwise the flyback diode won't be connected. I suggest you put it in the VN position.

war4peace

@dc42
I apologize, the schematic was primitive and did not exactly respect the pin layouts. When I physically connect the fan, I will look up pin order and connect appropriately.
Thank you very much for the VOUTLC jumper block mention, I would have surely missed it. VN position means leaving the 12V pin free, I assume? I apologize for asking these questions, I looked up "VN" in the Duet 3 6HC Wiring Diagram and there was no reference.