Hi All!
I’m working with a mini rambo 1.3a control board to build a new 3d printer.
I’m gathering that it is possible to run either a 12v or a 24v power supply with this board.Is this a correct assumption??
I’m building another prusa mk2.5 which has a set of splitting wires to step the Voltage down to 5v for a noctua fan.
I’m only familiar with the 12v applications from my other printer.
Will changing to a 24v power supply affect my fan voltages?
Fan voltage is connected to Vin so if you have a 24V power supply, you’ll need 24V fans. It will not matter for motors, endstop switches, or many other devices.
Motors are current controlled, so the drivers will control the amount of power going to them up to the current limit. For high speed printing, this can sometimes benefit from the higher voltage. I run all of my printers on 24V.
Switches are on logic circuits so they are on 3.3V or 5V lines, which will be regulated down from whatever the supply voltage is. These don’t need any changes at all. (Except the be sure that they are good with 3.3V or 5V, whichever it is that your board uses.) This isn’t likely to be a problem.
Fans are the weird in-between. Fans and heaters have to be matched to what your power supply provides, since they get the same main power. The bed heater (Unless you’re using an SSR to switch mains power to a silicone heater) hotend heater(s) and fans all get whatever voltage your power supply provides, and need to be matched to the power supply.
Thank you very much Dan!
At the moment I am set up with a 24v to 12v voltage reduction to run my board. I’m also running 2 mosfets to operate the 24v bed and extruder… I was hoping to get rid of all of that extra “baggage” and just drive everything from the board… sounds like it isn’t going to be that easy!
Prusa decided to put this noctua fan in and divide the power from 2 areas on the board to accommodate the lower voltage ,the fan circuit and part of the xmax circuit. I tried uploading a picture but it doesn’t look like it was going to come through.
So I guess I’ll have to go with my original plan of using the step down voltage regulator.
The blue boxes are fan, pink is for the 4 wire pinda.
If the Noctua port is using the XMax pin for 5V, it will still be 5V, regardless of what PSU you are using.
For my Duet, lots of people use a small buck boost voltage converter to run 12V fans with 24V power. The fan connectors switch the negative side, as do most boards, because the circuit is easier, so just using a 12V positive source for the fans only is a simple way to make it work.
Since the primary advantage for 24v is motor torque at speed, I’d much rather run the board on 24v and just use the voltage converter for fans.
