Burn M7

Hi!
I'm trying to activate a solenoid valve, which i did in the past with this schema : Controlling A Solenoid Valve With Arduino - BC Robotics

However, when i recreated today, the M7 component on my arduino uno burn/broke in half.. I cheked ever components (diode, resitor, tip120) and everything seems to work well. I'm using exactly the components from the schema. I use a really basic program (just putting the pin on HIGH), so I don't think the problem is there. I check many times if I connected components well and it does seem good.
I was wondering if anyone would know what went wrong + if anyone has info on M7 ?

Thank you !

janeczka_b:
I check many times if I connected components well and it does seem good.

Difficult to verify lacking an as-built schematic of your project.

Any help?

Not sure what a M7 component is, explain. A schematic, not a frizzy thing showing all the power supplies etc would help a lot. A Power Supply a Arduino is NOT.

M7 is a reverse polarity prevention diode (SMT version of 1N4002 I believe) in series with the barrel jack.
So, what voltage was connected to the barrel jack, what voltage and CURRENT was the solenoid and did you have a kickback diode with correct polarity across the solenoid coil? Were you drawing power from the VIN pin?
From the UNO Rev.3 schematic.
M7.png

M7.png

I connected a 12V power supply to the barrel jack and I was powering a 12V solenoid valve (a basic one : https://ussolid.com/u-s-solid-electric-solenoid-valve-3-8-12v-dc-solenoid-valve-brass-body-normally-closed-viton-seal.html).
I had a diode, the same one as in the schematic : Controlling A Solenoid Valve With Arduino - BC Robotics but when i checked after the arduino broked, the diode seems to still work. And i checked many times if it was the right side, so I dont think the problem is this (but cant be 100% sure)
Is it that the 1N4007 diode is not enough strong ?
I was draing power from the Vin pin (and ground from ground).

janeczka_b:
I connected a 12V power supply to the barrel jack and I was powering a 12V solenoid valve (a basic one : 3/8" NPT Electric Solenoid Valve 12-VDC Air, Gas,Fuel Normally Closed).
I had a diode, the same one as in the schematic : Controlling A Solenoid Valve With Arduino - BC Robotics but when i checked after the arduino broked, the diode seems to still work. And i checked many times if it was the right side, so I dont think the problem is this (but cant be 100% sure)
Is it that the 1N4007 diode is not enough strong ?
I was draing power from the Vin pin (and ground from ground).

Your solenoid is a 20W 12v unit. That means it will draw close to 2A when energized.

The Vin pin on the Arduino is for supplying the Arduino, not for powering external devices. When you connected the solenoid to this pin, all current to the solenoid passed through M7. If JCA34F is correct about it being a 1N4002 equivalent, that load is well in excess of the diode's current rating. It is not surprising that it burned.

S.

Two other notes which may be useful:

  1. Depending on your soldering skills and experience with SMT components, you may be able to replace the diode and repair your Uno. Whether or not it's worth doing is for you to decide.

  2. Note that the solenoid is not rated for continuous duty. You wouldn't want to use it to feed something that will be on for a long time, like lawn sprinklers.

S.

Thank you!! I understand. I did this schematic : Controlling a Solenoid Valve from an Arduino | Martyn Currey and it did work perfectly !

janeczka_b:
Thank you!! I understand. I did this schematic : Controlling a Solenoid Valve from an Arduino | Martyn Currey and it did work perfectly !

Good show. :slight_smile: So often, the devil's in the details.
S.

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