How to Bypass Alarm Door Sensor: Explained for Beginners

Bypassing an alarm door sensor can be a complex task, but with the right understanding and techniques, it can be done effectively. In this comprehensive guide, we’ll dive deep into the world of alarm door sensors, exploring the different types, their working mechanisms, and the step-by-step process to bypass them. Whether you’re a homeowner, a security enthusiast, or simply curious about the inner workings of these devices, this article will provide you with the knowledge and tools you need to navigate the world of alarm door sensor bypassing.

Understanding Alarm Door Sensors

Alarm door sensors are a crucial component of many home security systems, designed to detect when a door or window is opened. These sensors typically consist of two parts: a magnet and a reed switch. The reed switch is a type of electrical switch that is activated by the presence of a magnetic field. When the door or window is closed, the magnet is in close proximity to the reed switch, keeping the circuit closed. When the door or window is opened, the magnet is moved away from the reed switch, causing the circuit to open and triggering the alarm.

There are two main types of reed switches used in alarm door sensors:

1. Normally Open (NO) Reed Switches: These switches are open when there is no magnetic field present, and they close when a magnetic field is applied.
2. Normally Closed (NC) Reed Switches: These switches are closed when there is no magnetic field present, and they open when a magnetic field is applied.

Understanding the type of reed switch used in your alarm door sensor is crucial for determining the appropriate bypass method.

Bypassing Magnetic Door Contact Sensors

The most common type of alarm door sensor is the magnetic door contact sensor, which uses a reed switch and a permanent magnet. To bypass this type of sensor, you’ll need to mimic the sensor’s original magnetic field using a Hall effect sensor.

Step 1: Determine the Sensor Type

The first step in bypassing a magnetic door contact sensor is to determine the type of reed switch used in the sensor. You can do this by using a multimeter to measure the resistance of the sensor when the door is open and closed. If the resistance is high when the door is open and low when the door is closed, you have a normally open (NO) reed switch. If the resistance is low when the door is open and high when the door is closed, you have a normally closed (NC) reed switch.

Step 2: Acquire a Hall Effect Sensor

A Hall effect sensor is a device that can detect the presence and polarity of a magnetic field. To bypass the alarm door sensor, you’ll need to acquire a Hall effect sensor that is compatible with the type of reed switch used in your sensor.

Step 3: Determine the Polarity of the Sensor’s Magnet

Next, you’ll need to determine the polarity of the magnet used in the alarm door sensor. You can do this by using a Hall effect sensor to measure the magnetic field at the sensor’s location. Make a note of the polarity (north or south) of the magnet.

Step 4: Mimic the Sensor’s Magnetic Field

Once you’ve determined the polarity of the sensor’s magnet, you can use a Hall effect sensor to mimic the magnetic field. Place the Hall effect sensor near the alarm door sensor, with the same polarity as the original magnet. This will trick the sensor into thinking that the door is still closed, even when it is open.

Step 5: Test the Bypass

After placing the Hall effect sensor, open the door and check to see if the alarm is still triggered. If the alarm does not trigger, then you have successfully bypassed the sensor.

Bypassing Advanced Alarm Door Sensors

While the magnetic door contact sensor is the most common type of alarm door sensor, there are more advanced sensors that may require different bypass techniques. These include:

1. Multiple Reed Switch Sensors: These sensors use two or more reed switches to detect door or window movement. Bypassing these sensors may require mimicking the magnetic field of both switches.
2. Magnasphere Sensors: These sensors use a magnetically-actuated ball bearing switch instead of a reed switch. Bypassing these sensors may require a more sophisticated approach, such as using a strong external magnet to manipulate the ball bearing.
3. Dual-Technology Sensors: These sensors combine multiple detection technologies, such as magnetic and infrared, to provide more robust security. Bypassing these sensors may require addressing both detection methods.

Bypassing these advanced sensors may require more specialized knowledge and equipment, and it’s important to note that the legality and ethical implications of bypassing alarm systems should be carefully considered.

Conclusion

Bypassing alarm door sensors can be a complex task, but with the right understanding and techniques, it can be done effectively. By familiarizing yourself with the different types of sensors, their working mechanisms, and the appropriate bypass methods, you can navigate the world of alarm door sensor bypassing with confidence. Remember to always consider the legal and ethical implications of your actions, and use this knowledge responsibly.

References

1. Bypassing Basic Door Alarms – YouTube. (2018-09-23). Retrieved from https://www.youtube.com/watch?v=pPsSraQ3wlo
2. Bypass Alarm Sensor in a Home Security System. (2019-12-30). Retrieved from https://www.frontpointsecurity.com/blog/how-to-bypass-an-alarm-sensor
3. Your Guide on How to Bypass a Sensor – Brinks Home Security. Retrieved from https://brinkshome.com/smartcenter/your-guide-on-how-to-bypass-a-sensor
4. Interlogix – Simon Panels User Guide. Retrieved from https://www.interlogix.com/support/product-downloads/Pages/default.aspx
5. War Room – Bypassing Common Physical Security Interior Controls. Retrieved from https://warroom.rsmus.com/bypassing-common-physical-security-interior-controls/