Duet6HC: 24V and 48V PSU’s for different components

Notepad

You might find it easier to run a DC relay which is controlled by a 24v output of the 6HC.
I have done this a few times to control some unique heaters on some prototype hot ends - this allows 48V to be used without any risk of damaging the main motherboard.

Phaedrux

@woody said in Duet6HC: 24V and 48V PSU’s for different components:

I also have some stepper motors that require 24V.

Do they absolutely require 24v? Most accept a wide range.

droftarts

@woody said in Duet6HC: 24V and 48V PSU’s for different components:

My thinking was that I could take the (+) from the stepper motor and plug it into the 24V PSU directly, with the other 3 pins going into the 6HC driver.

Absolutely DO NOT DO THIS! That's not how stepper motors work. Stepper motors receive only a small voltage from the stepper motor driver, and they have two phases, effectively two circuits that have a coil each; see https://docs.duet3d.com/en/User_manual/Connecting_hardware/Motors_connecting#using-the-internal-drivers for a diagram.

If the motors "requires" 24V (and usually they are not rated by voltage, but by current), supply the 6HC with 24V. You can supply the extruders (heaters?) with 48V, either via a relay as @Notepad suggests, or by connecting the 48V positive to the heater, and the negative side to the 'out#' pin of the Duet 6HC 'OUT' connector. This is the side that is controlled on/off, so the heater will turn on and off as requested. Leave the PSU negatives tied together.

Ian

woody

@droftarts thank you all so much, really appreciate the feedback. Nice to have a community to ask.

I'm a total novice at this, can anyone help me breakdown how the relay works vs how just running the 48V positive to the extruder/negative to the "out#" works?

The 48V equipment is a ram extruder (to push out material) and a nozzle with a type of auger to mix the material close to the nozzle - both powered by NEMA stepper motors. I want to be able to control the speed and everything of this equipment through the Duet Web Control (along with the 24v stepper motors on the 6HC drivers).

I just ordered SSRs, but I'm thinking I can just order a Duet 3HC Expansion board for the 48V equipment (I think the Expansion board takes its own power/voltage), and wire the 48V directly to the expansion board. Thoughts?

dc42

@woody it's probably safe to power the 6HC from 48V because as has already been said, it's the maximum current that is critical and the drivers on the 6HC regulate the average voltage down to achieve the current you set. If you tell us the model of the stepper motors or post a link to their datasheet then we can check.

Notepad

@woody
Depending on the SSR you have purchased, some require a heatsink, some dont. If yours has an "optional" heatsink, this is actually mandatory as DC relays can get quite toasty.

We use a www.goldssr.com DC relay for our DC beds, and without a W70 heatsink they overheat

Just something to be aware of

woody

@Notepad Thank you guys for the advice! Please keep it coming

Latest:
I ordered a 3HC Expansion Board, I think I will run 48V to that and run 24V to the 6HC. I heard the drivers on the 6HC actually can't regulate the voltage if I plug in 24V stepper motors to the drivers.

So, on the 6HC:
-Running off 24V PSU
-Running 6 Nema17 Stepper Motors - looks like they're rated to 24V(https://www.amazon.com/gp/product/B00W9A2L3S/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1)

On the 3HC:
-Running off 48V PSU
-Running 1 Ram Extruder and 1 Nozzle Auger (which need 48V)

How does this sound?

jay_s_uk

@woody those steppers will work at 48v

Notepad

@woody

For future reference, if you look at a stepper motors data sheet, they normally have the rated voltage at something ridiculously low like 3.4V. This is the lowest voltage the motor can function with.

Almost all stepper motors can be run well past 60V so you don't have to worry if some amazon listing doesn't have the full data sheet available.

woody

All that workaround for nothing! Thank you guys.

Just for future learning and if it comes up again, does the setup I outlined work to have the 2 different voltages (using the expansion board)?

Notepad

@woody
Without seeing a wiring diagram of what you plan its hard for me to say if it will work.

But powering an expansion board like a 3HC with a different PSU is A-OK. One test machine I have has 3 different PSUs (one at 25V one at 30V and one at 42V)
If the expansion board is CAN controlled, then its important to know that power isn't transferred via CAN so you can power each expansion board with its own unique power if you so wanted.