Im in college and our research is about a fingerprint based door lock system. We really dont have any idea about arduino. Now we bought arduino mega for our research but I dont know how to connect all 6 solenoid locks to an arduino. Please help😥 It would be very much appreciated if you answer and it will be very helpful to us. I know there are same research about this in the internet but i cant find any of these. If you have any website about this research it would be very helpful. Thanks 😊

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    You simply cannot connect a solenoid to an Arduino, because an Arduino only outputs control signals and no power lines. There are 8 channel relais boards to put in between, if you want to minimIze self built electronics. – DataFiddler Sep 30 at 11:38
  • How much current do the solenoids need to engerize their coils? Solution might be as simple as using a TPIC6A595 shift register to sink current. ti.com/lit/ds/symlink/tpic6a595.pdf Available at Digikey.com If more than 350mA is needed, a discrete driver could also be used per solenoid, consisting of N-Channel MOSFET such as aosmd.com/res/data_sheets/AOI4286.pdf and a diode across the solenoid coil to dissipate coil generated current when the MOSFET turns off. – CrossRoads Sep 30 at 13:59

Supposing the lock you use is a simple solenoid that works with 12V, you should connect them to the output of a relay module, and then connect the Arduino to the module. Like this example here: link.

You will probably want to connect each solenoid to an individual relay, so you can activate each one of them individually. With that in mind you might want to use an 8-channel relay module like DataFiddler recommended. example

You will need a 12V power supply, and be sure to check the current drawn from your solenoids and see if the power supply can handle it.

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To follow up on CrossRoads' suggestion of a power MOSFET circuit, there is more detail on how to do it in an answer over in the Electrical Engineering group. Digikey.com is a great source for components.



You aren't going anywhere without external drivers. The Arduino simply can't output that much current. 8 channel drivers are widely available. Remember to connect an external power source.

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