Servo motor or solenoid ?

Hi guys,

I would to build a sustainable but safe locker for my project. It has to be cheap and consume little energy.Indeed, I would like to control several lockers with one arduino and I want to use it for a long time. I have made some investigation and most of the time people are using either a solenoid or a servo motor. Therefore, I would like to know your opinion on this matter, should I use a solenoid, a servo motor or something else ?

If you arrange a solenoid so the lock is closed when the solenoid is depowered it will probably be the most energy efficient and simplest solution. The Arduino just needs to apply power to the solenoid (through a transistor) for the short period required to open the lock.

A servo could be used to give a commanded open and close action but you would still need an arrangement (a transistor?) to allow the Arduino to turn on and off the power to the servo.

How are you going to open the lock if your system fails?


I personally think solenoids are probably the best fit for the job and it makes sense to have this configured so the lock is engaged when the solenoid is not energized. As far as low energy consumption? I'm not so sure that's going to be an option. Depending on the size of the solenoids you want to use anyway, and how many of them there are. You'll also want to make sure you construct this in such a way that the locks can't be maliciously bypassed. Obviously, that means there would be no way to get at the solenoid wiring or interface with the Arduino board. You're calling this a locker, so I'm going off of the assumption that you want to keep others out.

Solenoid. Nobody that cares about safety or duration uses a servo.

INTP: Nobody that cares about safety or duration uses a servo.

Why would it be less safe?


Because a servo doesn't have a definite position outside of code control. Power up, power down, power spike, you never know for sure where the servo is.

You do if it is disconnected from the power supply - which would be essential for power saving.


Have you considered car electric door locks, some have a motor and rack, so power only consumed during LOCK and UNLOCK.
They are also 12V, try ebay…

Thanks… Tom… :slight_smile: