How to Make a Low Cost Motion Detector With Basic Electronic Components


Making a motion detector at home can be a fun and educational electronics project. With just a few basic components, you can build your own motion sensing device on a budget. In this guide, I will walk you through the step-by-step process of creating a simple motion detector using common electronic parts.

Required Components

To build a basic motion detector, you will need the following components:

How a PIR Motion Sensor Works

The key component of this motion detector is the passive infrared (PIR) sensor. This inexpensive sensor allows the circuit to detect motion based on changes in infrared radiation.

Inside the PIR sensor are two detection elements made of a pyroelectric material that generates energy when exposed to infrared radiation. The sensor has a lens that focuses infrared radiation onto the two elements.

When a warm body like a human or animal passes in front of the lens, the amount of infrared radiation on the elements changes, causing them to generate a voltage signal. This signal is used to indicate motion.

So in summary, the PIR sensor detects the infrared radiation changes caused by motion and converts it into an electrical signal that can trigger other components.

Circuit Design

The circuit for this motion detector is simple, only requiring a few components connected as follows:

Here is a circuit diagram showing how the components are connected:

How to Make a Low Cost Motion Detector With Basic Electronic Components

How it works: When motion is detected, the PIR sensor output becomes high voltage. This turns the transistor ON, allowing current to flow through the LED and resistor. The LED lights up to indicate motion detected.

The 10k resistor is used to limit current flowing into the transistor base. The 1k resistor limits current through the LED.

Construction Tips

Follow these tips for constructing your motion detector circuit:

Applications and Uses

This motion detector circuit has many useful applications:

The sensitivity and range of the PIR sensor can be adjusted to suit specific needs. And additional components can be added like a buzzer alarm or to trigger a camera.

With just a few basic electronic parts, this DIY motion detector is inexpensive to build. The hands-on process of assembling the circuit also provides great experience working with electronic components.

Tips for Adjusting and Troubleshooting

To get your motion detector working properly, keep these tips in mind:

With attention to the sensor positioning and sensitivity adjustment, you can get reliable motion detection. This is a great DIY electronics project to build fundamental skills.


With the knowledge gained from building this motion sensing circuit, you can also try incorporating additional features like alarms, photography triggering or automated lighting activation. I hope you found this guide helpful for understanding how to create your own low cost PIR sensor motion detector using basic electronic components! Let me know if you have any other questions.