Duet 3 3HC - Controlling an Electro magnet to switch filament

hanshogeland

@bearer said in Duet 3 3HC - Controlling an Electro magnet to switch filament:

to check the peak current is within the ratings of the fet if using the magnet directly.

Thx, so there is a note on the 3HC stating MAX total 12V current draw: 800mA - so thats about 9.6W - having the magnet draws 220mA @5V + a converter from 24V to 5V and given that 5V 220mA are less than 12V 800mA I figure it should work having a step down regulator but its not my field of expertise so I might be wrong.

A Former User

@hanshogeland said in Duet 3 3HC - Controlling an Electro magnet to switch filament:

MAX total 12V current draw: 800mA - so thats about 9.6W

thats the onboard 12v regulator; if you're not using 12v you can ignore that limit.

having the magnet draws 220mA @5V

thats well below the rating for the fets on the duet, but I'm guessing the peak/inrush current is a little more then 220mA - this is what you need to check is below the rating of the fet on the duet.

dc42

Can you get the same electromagnet in a 12V or preferably 24V version?

hanshogeland

@dc42 yeah the easiest solution and it was about two Amazons click away. I have ordered a 24v magnet instead, then I guess there will be no issues driving a magnet from the mentioned OUT drivers?

whopping pochard

I am considering driving a solenoid of some sort with the Duet, and decided to just use one of these cheap little L298N H-bridge modules to isolate the Duet components in case inrush currents were more than expected:

https://www.amazon.com/HiLetgo-Controller-Stepper-H-Bridge-Mega2560/dp/B07BK1QL5T/ref=sr_1_5?dchild=1&keywords=h+bridge+driver&qid=1600126529&sr=8-5

dwuk

Thought it best to post against this old post - rather than create a new one.

I'm trying to create a automatically deployable XYZ ball probe - as per attached picture.

At present it is working with a 50kg Magnet to hold it in place on the bed

To make it automatically deployable I am thinking of replacing this with an 18kg electro magnet - like this one

Controlled from a fan output, via one of these

Will then use a fairly powerful servo to swing the probe out when needed, and retract it back when not in use.

Any thoughts appreciated.

For further background info see my 'Sovol SV08 Multiple Motion System Upgrade' thread.

jay_s_uk

@dwuk i've used 24v electromagnets connected to heater outputs before without issue

dwuk

@jay_s_uk Thanks - that was my initial thought too - but the post above from 'a former user' about inductive load issues worried me a bit.

I suppose with those Motor Driver boards I could probably even drive it from an IO.out pin too.

Will look further into the heater option before purchasing the driver boards.

droftarts

@dwuk said in Duet 3 3HC - Controlling an Electro magnet to switch filament:

Thought it best to post against this old post - rather than create a new one.

Rather than necro-post, create a new thread but add a link to the old thread.

Ian

dc42

@dwuk said in Duet 3 3HC - Controlling an Electro magnet to switch filament:

Thanks - that was my initial thought too - but the post above from 'a former user' about inductive load issues worried me a bit.

The heater outputs on the 3HC have built-in flyback diodes to protect them when used with inductive loads.

dwuk

@dc42 thanks for the confirmation - will go ahead without the motor driver boards then.

Ordered one of these

Doesn't look like it needs much power