Cheap Alternatives to Expensive Smart Home Sensors

Smart home technology promises a simple, automated life, but it often comes with a scary price tag. To completely decorate a home to experience movement, sound, light, and presence, you are expected to spend a lot of money on a collection of dedicated, single-purpose gadgets.

Whether you’re just getting started with home automation or you’re a geek looking to expand your coverage, relying on expensive, proprietary hardware creates a huge barrier. It seems like every new automation idea requires another trip to the store to find another important part. However, the answer to this problem may not be to buy more stuff, but instead to smartly replicate the sophisticated electronics you may already have.

You may have devices sitting unused in a drawer or controlled by just one limited function. Using the open source spirit of platforms like Home Assistant, you can use them for many smart home tasks. This method gives you the performance of other expensive marketing methods with the great benefit of privacy by keeping all data processing local to your machine. Check to see if you have these devices to overcome the high cost and limited use of dedicated smart sensors.

Instead of dropping hundreds of dollars on a bunch of smart home gadgets, one trick, you can get the same performance just by using an old PC microphone or a Bluetooth microphone that records high-quality audio. Plug an inexpensive peripheral, or one you already have, into a computer, and you can turn it into a powerful, general-purpose audio system.

Using a computer for this allows you to keep all your data processing stored locally, which gives you a huge privacy advantage over commercial systems that send your audio to cloud servers. All you have to do is install software like Snooper to regularly listen for sounds in your home and find specific, recognizable sound patterns.

Through digital signal processing and machine learning, the computer looks at the sound signatures of the incoming sound to find different frequencies and time characteristics. You can set the software to hear the loud, shrill chirping of a regular smoke alarm, the sudden crash of breaking glass, or everyday sounds like a doorbell ringing, a baby crying, or a dog barking. There are open-source sound classification models that can distinguish between dozens of detailed household activities, things like a running faucet, a microwave beeping, or a door closing.

Before you rush out to buy expensive infrared motion sensors or dedicated presence sensors for your home office, think about all the powerful sensors you already have. If you have a laptop sitting on your desk, you can repurpose the built-in hardware to act as a highly accurate smart home detector. Modern laptops use integrated mechanisms, such as Hall effect magnetic sensors or physical switches, to quickly tell when the display lid is opened or closed.

Instead of allowing this data to remain isolated within the computer’s operating system, you can connect it to your smart home ecosystem. This way you can build automation and get all your benefits without spending any money on additional hardware. To do this, you can use software such as Home Assistant desktop integration to report the status of the laptop lid and your overall user activity.

Depending on your specific operating system, you can install official Home Assistant apps. These systems act as a bridge, securely transmitting a variety of hardware signals to your smart home hub using protocols such as MQTT.

Although you can get a smart security camera for your home with good user reviews, you don’t need an expensive one. An old USB webcam is a really inexpensive way to keep e-waste out of landfills. The video conferencing units can also be easily connected to an always-on desktop PC, a spare laptop, or an inexpensive microcontroller like a Raspberry Pi to keep an eye on a door, hallway, or yard.

To activate this hardware, you can use powerful, free software like MotionEyeOS. This is a functional open source program designed specifically to turn a Raspberry Pi or similar single board computer into a smart, networked camera system. Alternatively, if you connect the webcam directly to a regular computer, applications such as iSpy have the same local ability to sense movement without hidden fees.

In this case, your repurposed webcam just needs to act as a responsive motion sensor. It can view a live video signal, local motion by looking at the percentage of pixels that have changed between frames, and know if something real has entered the area it’s viewing. Once it detects motion, the software simply needs to send a motion-detected signal or webhook to your central smart home hub, such as the Home Assistant.

An old Android phone is basically a Swiss Army knife of sensors. Instead of letting old devices sit there gathering dust, you can turn them into multi-sensory hubs. Although there are other useful ways to use your Android, this is a good move because it saves money on the hub.

By using the Home Assistant Companion app, you can show the phone’s internal sensors directly to your automation system without any complicated cables or cloud servers. A large variety of built-in components, such as accelerometer, gyroscope, proximity sensor, and GPS, opens up endless possibilities for smart home automation that knows what’s going on.

For example, you can install a device in the hallway to turn on the lights based on how much light there is, making sure that your path automatically lights up only when the room is naturally dark. The audio, visual, and radio features of a smartphone make it better than a typical motion detector. Using apps like Tasker or IP Webcam alongside the Home Assistant, the device’s microphone can act as a continuous sound sensor, listening for specific sound triggers.

This peripheral is probably the most commonly found in this list. Video game controllers are ubiquitous, feel great in your hand, and are designed for easy physical interaction. Instead of paying extra for dedicated, single-purpose home buttons or expensive proprietary touch panels, you can use the gamepad you already have sitting in the cupboard.

Game controllers act as standard peripherals, so any computer or Raspberry Pi running your smart home hub can pick up button presses, joystick movements, and accelerometer data as separate inputs. Whether you have a Nintendo Wii remote, Xbox controller, PlayStation gamepad, or Nintendo Switch Joy-Cons, you should be able to connect these devices via standard Bluetooth or USB. It’s a good idea to use a controller that’s already great on a PC since you’re likely to use that without its console.

The real power here comes from the software integration which brings a ton of customization options to you. Platforms like Home Assistant, Node-RED, or OpenSensorHub can capture input from these controls and do things your smart home system can do.