6 Motion Sensor DIY Ideas to Automate Your Home – MUO – MakeUseOf

Motion sensors are a great addition to your smart home setup and can be used in so many different ways, from detecting intruders to opening doors.
Motion sensors are an important part of today’s smart homes for monitoring and controlling various processes and alerting you if anything goes wrong. While you can buy smart solutions for your home, they can be quite costly. However, with some basic technical skills and inexpensive components, you can set up your own smart home system. Here are some motion sensor DIY ideas you can implement for home automation.
Motion sensors allow an electronic circuit to sense motion, and are typically used to detect whether an object has moved within or outside the sensor's range. These sensors are characterized by their small size, low cost, low power requirements, and ease of use, making them well-suited for both domestic and industrial use.
PIR (passive infrared) sensors, also known as pyroelectric sensors, can detect infrared radiations emitting from objects in the coverage area. These sensors often come in modular form with integrated support circuitry. The PIR motion sensor most commonly used by electronic hobbyists and students for DIY projects is the HC-SR501, which is quite easy to use. The sensor module has configurable settings to adjust sensitivity and output duration.
PIR sensors are ideal for basic projects that require detection of a person entering, leaving, or approaching an area. They are low power and low cost, pretty rugged, have wide coverage and range, and are easy to interface with.
It is worth mentioning that PIR motion sensors will inform you about the presence of human objects, but won't tell you how many are around or how close they are to the sensor—the sensitivity of the sensor is often fixed or calibrated for certain coverage. However, you can always try different sensor modules for improved performance and applications.
Having a mechanical light switch can be cumbersome, particularly when you need frequent access to light in a dark environment. Each time you would have to find the switch in the dark and manually turn it on, and then off again when leaving that place.
On the other hand, a motion sensor automatically turns on the lights after detecting the motion, and turns it off after a certain period of inactivity. This not only offers convenience but also conserves energy by turning on the lights only when needed.
For smooth operation, it's important that the automatic switching circuit has a timing control to ensure the lights stay on long enough for the user to leave the area safely. Using a PIR motion sensor with a microcontroller board, you can build a smart motion-sensing light switch.
Another great use for a PIR motion sensor is for controlling water faucets (taps) for a basin. This idea is quite useful as a way to conserve water: many people have the habit of using water carelessly in the basin, keeping the (manual) faucet on for a longer time than is actually needed.
Using PIR motion sensing and controlling circuitry, you can set the faucet to turn on for a predetermined time once it detects movement. You can control water flow using an DC electric valve. Its DC voltage is controlled using an electric circuit, which not only manages the timing requirement for the electric valve to remain on but also supplies its power.
This idea proved quite useful during the pandemic, when it was crucial to minimize the physical contact to prevent the spread of contagious disease.
Ceiling and exhaust/extractor fans help to maintain air circulation and ventilation, especially in hot weather. However, we tend to forget to turn off the fan when leaving the room.
By integrating your ceiling or exhaust fans with motion sensor-based electronic switching circuits with appropriate delays (for user-friendly device operation), you not only automate the switching process but can also save energy at home.
If you are a hobbyist, we recommend you use a DC fan for this DIY project; otherwise, seek help from an electrician for AC fan connections to ensure safety.
Using a PIR motion sensor, you can build a highly effective and low-cost intruder alarm, particularly in situations where there is no movement expected at all, such as when you are away from home.
It is important to place the sensor in the best place to intercept any potential intruder, such as near a door. You can then connect the output of the sensor to the electronic circuit and set an alarm to switch on if an intruder is detected.
The time for which the alarm should sound can be adjusted through the sensor module or electronic circuit. Alternatively, you can do so in a program running on a connected microcontroller, such as the one used for this Raspberry Pi Pico intruder alarm.
You can also extend this project by relaying the sensor signal through Wi-Fi to the user's cell phone to notify them of any malicious or unwanted activity at their premises. Once alerted, the user could also check their home through CCTV cameras for improved surveillance.
PIR motion sensors can also be used to design an automatic doorbell that informs the user of someone's presence at the door. This project is similar to the aforementioned intruder alarm, but its application is different.
You may not need to install a manual doorbell that requires guests to manually operate it to inform the host about their presence. As long as someone is at the door, the sensor detects their presence and notifies you about it. Using a suitable microcontroller or single-board computer, you can also link this project through Wi-Fi to receive notifications on your phone.
Another common application of PIR motion sensors is in an automatic door opener. This slides open the door when a person approaches it, and then closes it after a few seconds if it does not detect anybody. You have probably seen such doors in shopping malls, hospitals, and hotels.
For your home, you can build yourself a similar door system for the main living area of the house. These automatic doors can provide isolation for an air-conditioned hall, TV lounge, or common sitting area in the house.
By now you should have a good idea of how to use PIR motion sensors in everyday domestic applications. These sensors not only automate the appliances and devices but also help in efficient management of resources. You can also integrate these project ideas with an IoT-based system to automate and monitor your home remotely.
Ummara is a staff writer at MUO whose work focuses primarily on Linux. She has a degree in Telecommunication Engineering and has been writing about Linux for about 3 years.