Connecting a 12V DC fan directly to a 24V DC power source will lead to fan damage.
When the voltage is converted from 24V to 12V first, however, it is, of course, possible to connect 12V fans.
One option for doing this is our NA-VC1 step-down converter. It is a compact converter that ensures that our 12V fans can be used safely on applications that provide 24V DC via the fan header, for example on many 3D printer models.
As the RPM and PWM signal are passed through, speed-controlling the fans is therefore still possible.
Several fans can be connected to one NA-VC1, if their combined power consumption isn't any higher than 9W.