How to power the Mini5P from external 5V (no SBC)?

jay_s_uk

@zapta yes, sorry. add a jumper to it as well

zapta

jay_s_uk

@zapta too early in the morning and my brain isn't fully in gear!

droftarts

@zapta said in How to power the Mini5P from external 5V (no SBC)?:

At one point it says "see the "Powering the board, 5V supply" section below for more information" but I can't find that section.

Sorry, that should link to https://duet3d.dozuki.com/Wiki/Duet_3_Mini_5plus_Hardware_overview#Section_5V_Power_Options on the Hardware page. Copy/paste error, will fix.

Fixed. Also changed Hardware page to recommend disabling internal 5V regulator:

5V_EXT_INPUT: With the 5V_SELECT jumper set to this position, 5V is passed through to both 5V_EXT and 5V_INT from the EXT_5V header. When using EXT_5V, add jumper to Int_5V_Disable, to disable the onboard 5V regulator. The EXT_5V header also has a pin for controlling an external power supply (note signal shared with io4.out). This allows for the board to be powered from 5V, with an external supply for VIN turned on and off as required.

Ian

zapta

Thanks @droftarts.

fcwilt

@zapta

Why do you want to bother with an external 5V supply?

Frederick

zapta

@fcwilt, my goal is having the duet being able to shut off power in emergency to heaters and motors while still staying alive so I can see its status.

I plan to achieve it using a electromechanical relay that is controlled by ps_on and feeds the 110VAC to the 24VDC power supply and the 110VAC heatbed's SSR.

For 5V I plan to use Mean Well RS-25-5 which is small and fanless.

Any reason not to go with this plan?

zapta

@fcwilt, that's the plan. (Relay flyback diode not shown).

fcwilt

@zapta said in How to power the Mini5P from external 5V (no SBC)?:

@fcwilt, my goal is having the duet being able to shut off power in emergency to heaters and motors while still staying alive so I can see its status.

I plan to achieve it using a electromechanical relay that is controlled by ps_on and feeds the 110VAC to the 24VDC power supply and the 110VAC heatbed's SSR.

For 5V I plan to use Mean Well RS-25-5 which is small and fanless.

Any reason not to go with this plan?

What sort of emergencies do you anticipate?

In the years I have been building and using 3D printers I have never encountered a need for this sort of setup.

Frederick

engikeneer

@zapta I do this on my Duet WiFi and plan to when I get round to building my next printer (toolchanger with a D3Mini + expansions).

Two things to be aware of. If you use expansion boards, they won't be powered until you turn on the 24v supply, so have to be reconfigured after. I guess you can just turn on the relay from config though, or do a macro that turns it on and configures the expansion boards.

Other thing is inrush currents from DC PSUs which can be several times the normal peak current. I welded my first relay shut with the inrush current after a few cycles when first setting up my printer. That was a cheap 10A relay. Now I use a pair of 30A relays on both the HV and LV side of the PSU and not had any problems

zapta

@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:

What sort of emergencies do you anticipate?

Mostly a heater power mosfet/ssr becoming permanently short.

fcwilt

@zapta said in How to power the Mini5P from external 5V (no SBC)?:

@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:

What sort of emergencies do you anticipate?

Mostly a heater power mosfet/ssr becoming permanently short.

I'm not sure what you can learn from the firmware if a device like that fails.

Perhaps install thermal cutouts on the heat generating devices which will protect you from any source of too much heat, not just device failures.

Frederick

zapta

@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:

I'm not sure what you can learn from the firmware if a device like that fails.

If it happens during printing, the firmware detects it (abnormal PID behavior) and shuts off PS ON. I have a similar setting in my current printer (HEVO) and I confirmed that it works.

I also have thermal fuse on the bed but not on the nozzle heater.

fcwilt

@zapta said in How to power the Mini5P from external 5V (no SBC)?:

@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:

I'm not sure what you can learn from the firmware if a device like that fails.

If it happens during printing, the firmware detects it (abnormal PID behavior) and shuts off PS ON. I have a similar setting in my current printer (HEVO) and I confirmed that it works.

I also have thermal fuse on the bed but not on the nozzle heater.

I know it does that but the firmware doesn't know the reason.

As long as you are happy with the result that is all that matters.

Frederick

engikeneer

@fcwilt you're right you don't know the 'reason' but you at least know which heater it is, and can maybe see the temperature graph

Nurgelrot

@zapta I have a Mini5 configured in exactly this way. Can't say that I actually use the relay much and I may change it because of that.

I have a good quality (meanwell) 5v psu and a 24V psu both wired to the same mains switch. The mains passed through the AC side of the 5v psu and goes to a NO High Trigger relay before the 24V psu to control VIN.

Out from the 5v psu I have power lines running to 5v_EXT_in on the Mini5.

Also Out on the 5v I have 2 +5v lines one running to DC+ and IN on the DC side of the relay.

Then a single wire runs from the pson pin on the Mini5 to DC- on the relay.

24v VIN is wired normally after the relay.

In config.g very near the top I have a M80 to close the relay and apply 24V when the 5v power is applied. I can then turn off 24v from the duet as desired.

Hope that makes sense. Please be sure of what you are doing before hooking stuff up.

Also note that all of this is using the same ground. If you mix a ground in from another source bad things will probably happen.

zapta

@nurgelrot, I think your system is exactly what I would to have here.

What relay are you using? I got Digikey CCM1871-ND. It's a 30A relay (used with a flyback diode).

https://www.digikey.com/en/products/detail/te-connectivity-potter-brumfield-relays/T9AS1D12-5/1095335

I understand that all the AC grounds should be connected and all the DC (-) should be connected but am still debating if to connect the grounds and the (-). In my current printer the DC is floating.
My frame is well grounded (in a few places, with anodize removed) but the X/Y rails of the gantry are not (this is a Voron 2.4, the gantry also moves on the Z axis). I may ground it as well.
I also install a wall socket with a GFCI interrupter so any AC leak to ground will cut power immediately.

Nurgelrot

@zapta Mine is just a generic 10A https://www.amazon.com/HiLetgo-Channel-optocoupler-Support-Trigger/dp/B00LW15A4W/ref=sr_1_6?dchild=1&keywords=relay+switch&qid=1629233141&sr=8-6 Seems to be fine for this application.

zapta

@nurgelrot, I picked a 30A relay for a concern regarding the inrush current of the UHP-200-24 power supply (40A@110VAC, 80A@220VAC).

Got this din rail mounted 12VDC relay and replace with a similar one for 5VDC relay.

https://www.amazon.com/gp/product/B00UA46BFE

Was not sure how the relay continuous current rating applies to momentay inrush current.

zapta

@fcwilt said in How to power the Mini5P from external 5V (no SBC)?:

In the years I have been building and using 3D printers I have never encountered a need for this sort of setup.

Around here our homes are built of dry wood. May require more fire awareness than those bricks dwellers.