12v 40mm cooling fan replacing the original 24v

Hello, I’m just curious how are other Taz 5/6 owners powering their aftermarket 12v 40mm part cooling fan in place of the original 24v.

As multiple posts suggests, most non-original 24v fans have issue with RAMBo’s PWM at low RPM, some have suggested using 12v fan instead as there are many more choices. I came across this post regarding dropping the RAMBo’s 24v output to 12v using Zener diodes so I ordered a few 12v and 6v diodes to experiment.

The good news is that 12v fans work exactly as expected, but what I am concerned about is the incredible amount of heat the one 12v diode was generating, by simply touching hot end thermistor to the diode it was reading over 70C! Not sure how I would have to keep this thing from melting nearby wires.

Curious how are fellow Taz owners getting 12vs to run properly with Taz’s PWM and not use an external power source, or if anyone has any suggestions on well priced 24v fans that are easily accessible.


I don’t. I used 5v 40mm fans there.

Are you using the 3 watt diodes that was linked to in the other forum topic? And he used 2 - 3 watt 6 volt diodes which gave him 6 watts of power dissipation.

Myself I just replace the 24 volt fans, so do not plan to use 12 volt fans.

The 12v diodes I was using were 5w, I shut it off when it got to around 80C as I got a little concerned, didn’t test for max temperature.

I just ran a test with 2x 3w 6v diodes (same as linked in the other thread) and ran an extended test. under 60% fan load they stabilized around 60-75 degrees C enclosed in heat shrink, under 100% fan load they got as hot as 95C and stabilized. These temps are higher than I’d like (of course) but should I be concerned about their reliability? If they are able to work fine I’ll just have to pay attention to insulate the heat against other wires.


The specs for the parts he linked to are good up to about 200C.