MOSFETs, Solenoids, and Arduino UNO R3

I picked up this MOSFET board from Ebay:

I'm trying to use the following components:

12VDC 10A Switching Power Supply
Arduino UNO R3
12VDC 75W Solenoid

I have 22AWG pos/neg from the power supply to the Arduino.

I have 16AWG neg from the power supply to the MOSFET board input.

I have 16AWG neg from the MOSFET board output (FET 1), to the solenoid.

I have 16AWG pos from the power supply to the solenoid.

At the solenoid, I have a transient voltage diode between the pos/neg connects to protect the MOSFET from spikes as the solenoid field collapses.

My issue is that when the Arduino commands the MOSFET board to fire the solenoid, the voltage on the Arduino is pulled down to the point the board reboots.


Well, I seem to have found the issue, but I have no solution.

I tried hooking the solenoid directly up to the power supply with the Arduino powered up to the same supply. No issues.

I then did the same, putting a the transient voltage diode between the solenoid terminals. It pulled the voltage of the power supply down to nothing, and after a couple of hits, fried the diode.

Apparently I was misinformed regarding using the transient voltage diode?

Should I have used a regular diode?

What voltage/power rating is the TVS diode?

Are you sure you've not connected the FET drain to +12V by mistake?

Are you running high current wiring in parallel with signal wiring - they should be kept apart, and
each high current wire ought to be twisted-pair with its return current wire. So twisted pair from
12V supply to the inputs of the MOSFET board, twisted pair from the MOSFET output to the load.
That will reduce the transient interference from the high current circuits.

Have you checked the supply will happily power the load/TVS combination directly without tripping out?

Postings crossed over - that's why I asked the voltage/power rating of the TVS. You can use any
ordinary diode as a free-wheel diode so long as it can handle 6.5A transients.

BTW you should never be hooking a highly inductive load to a supply (other than a battery) without
a free-wheel diode or other protection - inductive loads kick back hard enough to break circuits if
not tamed.

A 70W solenoid will be storing a lot of energy, make sure you don't become the protection device
yourself, it might well be in the range that's potentially lethal.

Welcome to the forum.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png? (Not Fritzy diagram)

Also a picture of your project so we can see your component layout.

Thanks.. Tom.... :slight_smile:

Is that what you are describing?

Sounds like you might have had the diode across the coil flipped end for end.
Solenoid driver.jpg

Sorry, but due to an NDA, I cannot post a photo of the actual design.

I have cycled the solenoid nearly 10k times now, and the MOSFET is still working. It is wired as per the attached photo.

Seems the TVS was the issue. A standard Schottky is working fine.



Please note the circuit supplied by CrossRoads, the 270R and 10K resisitors are very important, also the correct polarity of the diode across the solenoid.

Tom..... :slight_smile: