@samlogan87 As well as the "L" parameter, there is also the "X" parameter which will limit the maximum fan speed. It might be worth having a play around with that to see if you can get adequate cooling at a lower (and therefore quieter) speed.
BTW - do you have any details of the air pump you are using for part cooling.? It's something I am considering doing and I've been looking at pond air pumps but noise level data is a scarce.
Hi everyone, I solved this buying a silicon cover for the heat block (as Phaedrux mentioned) you can get some pretty cheap on Ebay, I also realised that you don't need to have a E3D hotend, they are not available for every hotend, but you can found for the most common. With this the temperature only goes down 5 degrees and in a few seconds it's in the desired temperature again.
I agree, ordinary 2-wire PWM fans are not designed to work with PWM.
I assume you meant 2-wire non- PWM fans?
I just meant 2-wire fans.
Varying the voltage for the fan on the basis of a PWM signal doesn't require a slow signal and, in my view, is the optimal solution.
However, I do appreciate it may be problematic in terms of cost and/or PCB real-estate. If that's the case, I think dropping the PWM approach altogether and going with direct voltage control would still be much better than the current implementation.
Direct voltage control also requires a lot of PCB real estate. You need large inductors and capacitors to smooth the PWM to something approaching DC, then probably more inductors and capacitors to keep the EMI under control.
But, like you say, almost nobody uses PWM fans - at least not for the small effector fans where speed control is crucial - as they are very hard (if not impossible) to find. Incredibly hard to believe no company in the market realized yet that such fans would be an instant hit with consumers.
Noctua has informed me that they will be bringing out a range of smaller PWM-controllable fans, in both 12V and 24V versions. So I think they will become more common. In the next generation Duets we will probably provide at least one 4-pin fan connector.