My simple LED strip controller, Part 1

Apr 24, 2017 · 2 minute read
electronicsMCU

Introduction

I have this nice dark and narrow alley at my place between the garage and my front door. To shy away dubious creatures and to see not only where I’m going but also whether there’s something in my mailbox I want to have some motion activated light in there. Since it is long and narrow and has a not-to-high flat roof on top using one of the typical motion activated spots is not a good fit. Instead I wanted to mount a LED strip in one of those nice angled aluminium profiles along the alley and have that not only motion activated but also only activate in the dark to not waste energy during broad daylight.

To get my idea implemented about 2 years ago, I started a very simplistic approach of simply connecting parts together; those parts were:

• a 12V power supply
• an adjustable light sensor module with a built-in relay
• a PIR sensor with a strapped on MOSFET
• a LED light strip

In a nutshell the 12V PSU provides the power for the light sensor, the relay switches the power over to the PIR sensor in darkness, the PIR sensor activates on motion and uses the MOSFET to switch the very same 12V over to the connected light strip for some time and then turns it off again.

It worked okay for a year or so and then it started to act funny so it was time to do it properly…

The wishlist

Rather than just plugging random components together the solution to build should have the following items:

• Single 12V input via barrell plug
• Single 12V output via barrell plug
• Custom PCB
• MCU controlled, socketed
• Pluggable components
  • Light sensor (LDR)
  • Motion sensor (PIR)
  • Light strip

To be continued …