Introduction: Motion Activated Security Yard Sign

Traditional security system yard signs don't do anything. In fact they haven't changed much over the past 30 years. However, they are a valuable deterrent as long as they are placed in a conspicuous spot in your yard and look well maintained.

I love my smart home, except for the dumb yard sign. I thought to myself, how can I make the yard sign appear smart like the rest of my home? Now when someone gets within 15 feet of my home at night, 8 super bright LEDs on the yard sign light up to remind them that this home is a smart home!

Step 1: Let's Face It, Security Yard Signs Are Boring

This Instructable shows you how to upgrade your old yard sign making it intelligent and better at deterring crime. My new yard sign is completely wireless--no cords to plug in, no batteries to replace, no micro controllers, no WiFi, no fuss.

Step 2: Shopping List

To build a Smart Home Security Yard Sign you will need the following parts:

  1. Security system yard sign (obviously). Nearly all security alarm companies will send you a new sign if you ask. If you security company has a customer web portal (like log in and look for a link to request new yard signs and window decals. If you don't see it, give them a call. Most companies won't charge you for a replacement, as long as you don't abuse the system and order a replacement too frequently.
  2. PIR Motion Sensor. I used this one from Adafruit
  3. Round Solar Panel. I looked around and couldn't find one small enough to blend in, so I purchased this one from Adafruit. It's actually a "skill badge" but it is perfect for this project--and cheap!
  4. Super bright LED (quantity 8). I purchased a few 5 packs of warm white from Adafruit. You can also get really cool colored LEDs. Adafruit LED Sequins - Warm White
  5. Small gauge wire. 20-22 AWG wire works great for this project
  6. Lithium Ion Polymer Battery - 3.7v. Anywhere from 150 mAh to 350 mAh battery will work, depending on whether or not you live in an area that doesn't get much sunlight.

  7. LiPoly Backpack Add-on. This inexpensive board is what allows you to charge the battery with solar power and powers the LEDs.

    If I remember correctly, the total for all of the parts was around $30.

Step 3: Wire It Up

  1. I started by drilling holes through the yard sign where I wanted the super bright LEDs to be placed. Since my yard sign is in the shape of an octagon, I placed one LED at each of the corners.
  2. The LED sequins are pretty small. Connect a wire from the positive (+) terminal of one LED to the positive terminal of the next LED. Repeat until you have connected all positive terminals together.
  3. Connect a wire from the negative (-) terminal of one LED to the negative terminal of the next LED. Repeat until you have connected all negative terminals together.
  4. Connect the PIR motion sensor wires: (This page provides a great overview on the PIR motion sensor and how it works)
    1. 5V - connect to the BAT pin of the LiPoly backpack
    2. GND - connect to the common ground pin on the LiPoly backpack
    3. OUT -connect to the positive terminal of of of the LED that is daisy chained to all of the other LEDs
  5. With the rechargeable battery unplugged from the LiPoly backpack, connect the wires:
    1. 5V - this is the pin that comes from the solar power to charge the battery.
    2. G - this is the common ground pin, shared with the battery, the negative terminal of the LED, the negative terminal of the PIR motion sensor, and the negative cable for the solar power.
    3. BAT - this is the voltage out from the battery, which will range from 3.2V when the battery is dead to 4.2V when it's charged.
  6. Connect the positive (+) terminal of the solar panel to the 5V pin of the LiPoly backpack
  7. Connect the negative (-) terminal of the solar panel to the G pin of the LiPoly backpack

You can adjust the sensitivity as well as the time between re-triggers by gently twisting the knobs on the back of the PIR motion sensor. Turning the sensitivity potentiometer clockwise makes it more sensitive. Turning the time potentiometer adjusts how long the LEDs are lit after it detects movement.

Step 4: Enjoy Having the Smartest Security Yard Sign in Your Neighborhood

Congratulations! You have finished your build. Now place the yard sign back in front of your home and angle the solar collector so that it points towards the sun and charges the LiPoly battery.

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