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

hanshogeland

Hi!

I´m developing a type of filament changer lift mechanism to be able to change filament coming out of a filament feeder.
This is to be able to change the filament to my 3 Hemera tools.

I have an electro magnet, with these specs:

Dimensions: ø20 x 15mm
Maximum holding force: 2.5Kg
Nominal voltage: 5VDC
Current draw: 220mA
Lead length: 270mm
It has a name ELE P 20/15

I´m thinking to control the magnet on/off using the one of the "FAN" OUT7-9 on the 3HC

My question:
Since I´m not sure how a magnet will affect the board, I´d like to ask about my options to controll the magnet.
I have a thought of using either a relay or a 24v to 5v dc controller card. Any input of the matter would be grateful which one is best to use or if anyone have other suggestions?

Link to the Magnet https://www.electrokit.com/en/product/elektromagnet-o20x15mm-2-5kg/
Link to the 24-5v converter

Link to step down regulator
https://www.amazon.com/dp/B07CVBG8CT/ref=cm_sw_em_r_mt_dp_-3jxFbFKV05M3

A WIP picture/sketch of the Feeder and "magnet" lifter, on top of the green

A Former User

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

Since I´m not sure how a magnet will affect the board, I´d like to ask about my options to controll the magnet.
I have a thought of using either a relay or a 24v to 5v dc controller card. Any input of the matter would be grateful which one is best to use or if anyone have other suggestions?

you'd want to use fan outputs in either case as they have diodes to deal with the inductive load (heaters do not).

you'd also want to check the peak current is within the ratings of the fet if using the magnet directly.

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