powering a solenoid

Thread Starter


Joined Sep 16, 2020
I'm using MIDI triggered solenoids to make a percussion robot.

I have a larger 12vdc 8a solenoid that I want to use. I had an earlier setup with an Arduino Leonardo card. With that, in order to power that solenoid I used an IRF520 Mosfet module (please see attached pic) with a 12v 10a power supply.

Now instead of an Arduino I am making a system with a card called MIDi Switcher shown here: https://six4pix.net/product/midiswitcher/

The card can handle eight solenoids but has an 8a maximum, so if I use the card as is I can only hook up 1 solenoid, so I'd like to use an external mosfet with an external power supply like i did with the Arduino setup.

The manufacturer of the MIDI Switcher states:
The MIDI switcher outputs are “open drain” so when they are “on” they provide a path to ground. This means the screw terminals on the MIDI switcher could switch an external PNP transistor or P-MOSFET (these are switched “on” when their base/gate is “pulled down”) but the could not switch an NPN or N-MOSFET (switched when their base/gate is “switched on”)

From what I can tell, the IRF520 module I have is NPN so is the wrong type. Please correct me if that isn't right.

Is there a similar module that I can use for this? I like having a module that has the screw terminals, it makes for easy hookup.

I might also mention that it could be that my total amperage is below 8a so I don't need to even use an external mosfet. But I would feel safer using an external module. The Midi Switcher card runs on 12vdc so that would be the voltage it would send out to an external module.



Joined Dec 2, 2017
You could put a low power P-channel MOSFET in between each of the MIDi switcher channels and your IRF520 modules. (need pullup/down resistors)

If you look hard you might be able to find an 8 channel inverting high side load driver chip. (8 channels, one chip)


Joined Jul 18, 2013
I am not really familiar with using an Arduino, but can you not use the required number of logic gate mosfets from Arduino outputs?
This is the way I would do it with a Picmicro.


Joined Aug 7, 2020
For how long will each solenoid be energised? Presumably it only takes milliseconds for it to actuate? In which case there won't be many solenoids on at the same time? 8A will be an average current, and it will be a thermal limitation, so can be averaged over a number of seconds. Give it a try and see how warm it gets before you start looking for a complicated solution.


Joined Jan 15, 2015
Your solenoids are 8 amp which is a pretty large solenoid current. Your IRF 520 was a N channel MOSFET and you were likely doing low side switching. Your new MIDI switch can handle 8 amps per channel and a little more depending on the application. Eight amps continuous and more when pulsed. I guess that other than running at max for continuous current I don't see where the problem is?


Thread Starter


Joined Sep 16, 2020
ElectricSpidey thanks it's good to know that there is some way to do this.

IanO and Ron, after I posted the question, I started hooking up the solenoids, the 8a one and the a large Adafruit 12v solenoid and ran a few Midi tests and neither the solenoids nor the Midi Switcher card got warm at all. It's like you said, the whole thing is so intermittent that I am probably being over cautious. The solenoids will rarely fire at the same time and the on time works out to be only about 10-20ms with lots of down time.

So I'm going to use the card as is and just watch the temperature.

Thanks everybody I appreciate the help.