driving 24v 4A 6Ohm solenoids, selection of flyback diode
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Hi,
I wanted to quickly ask,
I wanted to drive a Solenoid (6 Ohm, rated for 12v and 2A, Duty cycle 10%) off of the expansion board on the Duet.
It is only actuated momentarily with 24v for switching the hotends, so i think the duty cycle with the higher current should be fine.
https://www.youtube.com/watch?v=fYOE01SzS9QMy question is if one of those Diodes would be fine?
https://www.reichelt.de/gleichrichterdiode-1000-v-15-a-axial-px-1500m-dio-p217011.html?&trstct=pol_8
https://www.reichelt.de/gleichrichterdiode-1000-v-12-a-to-220ac-byt-12p-1000-p6356.html?&trstct=pol_7And the mosfets would be those
Thank you
Max
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Either of those diodes will be more than adequate. The mosfet board will it be suitable if it will work from a 3.3V control signal.
Alternatively, if the E1 heater output on your Duet is spare, connect it to that. You still need the flyback diode.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
@dc42
Hi dc42, thank you for answering so quickly.
No, the E1 heater output is not to spare sadly.
I was thinking of using the two PWM ports on the duet expansion breakout board?What do you mean by
The mosfet board will it be suitable if it will work from a 3.3V control signal.
Do you mean the mosfet board does not work on 5v?
If so, do i have to connect it to the board itself?
Which pins would be suitable for that?Thank you
Max -
The PWM ports provide 5V drive. Check that your mosfet board is ok with that.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
From this "diagram"
They list that the mosfet is to be connected directly to the old mosfet heated bed output, so i guess 12-24v
Does that mean that 5v is OK or does that mean that maybe 5V is not enough?Thank you
Max -
It means that 5V may not be enough.
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To shortly get back to this topic,
Indeed the linked mosfets did not accept 5V voltage.
I have now gotten some IRF520 Mosfet boards with somewhere around 6.5 amp continuous drain current, which should be enough, and they do work.But i noticed, after switching the solenoids have much less power (maybe half) than if i hold them directly to the 24v power supply.
I do not have a multimeter, but it has to mean that the mosfets "steal" voltage.
Is that possible?
They also get extremely hot from just two seconds of engagement, as if they have a lot of bypass current that gets converted to heat inside the mosfet.
Is there any way i can reduce that? Will it help if i put two mosfets in parallel?Thanks
Max -
@nitrofreak Cheap SSRs usually have a high on resistance and use lower current mosfets, like the fake FOTEKs you can get on ebay.
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@stephen6309 said in driving 24v 4A 6Ohm solenoids, selection of flyback diode:
@nitrofreak Cheap SSRs usually have a high on resistance and use lower current mosfets, like the fake FOTEKs you can get on ebay.
I´m not using SSR´s, i am using mosfets to drive the solenoids.
My solution now is to connect the small mosfets to the input of the big mosfets, so as to let the big ones drive the current while the small ones just activate the big ones with 24V.
Not pretty, but seems to work until i have a better solution -
@nitrofreak said in driving 24v 4A 6Ohm solenoids, selection of flyback diode:
@stephen6309 said in driving 24v 4A 6Ohm solenoids, selection of flyback diode:
@nitrofreak Cheap SSRs usually have a high on resistance and use lower current mosfets, like the fake FOTEKs you can get on ebay.
I´m not using SSR´s, i am using mosfets to drive the solenoids.
My solution now is to connect the small mosfets to the input of the big mosfets, so as to let the big ones drive the current while the small ones just activate the big ones with 24V.
Not pretty, but seems to work until i have a better solutionI can recommend these Power Expander
Doug
