A friend of mine asked me if I couldn’t make a door lock that could be controlled from his desk without him getting up all the time. He showed me a video of a sliding bolt with a servo controlled by an Arduino. Something like that, he said.

It is not very complicated to control a servo with an Arduino and then attach the servo to a sliding bolt. However, making it remote-controlled requires a bit more work. Remotely controlling over Bluetooth or Wi-Fi is possible, but that implies creating an app for a smartphone or building a web interface, and I didn’t want to go into that.

An nRF24-based solution would be nicer, but then also you must build a remote control. This is doable, of course, but requires engineering. Infrared would be an option, but then you must point the RC at the lock, which is inconvenient. So, I started thinking of another approach.

Use Remote-Controlled Car Parts

Probably one of the most common use cases for remote-controlled locks are cars. Today, every car has a central locking system with remote control. It is easy to find spare parts for these systems, and I bought a car lock servo online for less than €10.

On the internet you can also find very cheap remote-controlled relays intended for garage door openers, motors and pumps and similar applications, and they come with a nice keychain remote control including batteries. They look much better than anything I can build myself. Some of them even come with an enclosure for the relay.

This video shows what I came up with.