MQ135 Gas Sensor Library for Proteus: Download and Setup Guide
Designing air quality monitoring systems or smoke detectors often requires simulating the MQ135 Gas Sensor before moving to hardware. However, Proteus Design Suite does not include this sensor in its default library.
To bridge this gap, you need to download and install a third-party library. This guide provides a step-by-step walkthrough to get your MQ135 simulation up and running. Why Use the MQ135 Sensor?
The MQ135 is a versatile air quality sensor capable of detecting: Ammonia (NH3) Nitrogen Oxides (NOx) Alcohol Benzene Smoke and CO2
In Proteus, simulating this sensor allows you to test your Arduino, PIC, or 8051 code against varying gas concentrations without risking hardware damage. How to Download the MQ135 Library for Proteus
Since Proteus doesn't come with gas sensors pre-installed, follow these steps to find the "UPD Work" (Updated/Working) files:
Search for the Library: Look for the "Gas Sensor Library for Proteus" on reputable engineering forums or GitHub repositories (often bundled as a "MQ Sensor Pack").
Download the ZIP File: Ensure the package includes two essential file types: .LIB (Library file) .IDX (Index file) Step-by-Step Installation Guide
Once you have downloaded the library files, follow these steps to integrate them into Proteus: 1. Locate the Proteus Library Folder The directory varies based on your version:
Proteus 8 (Modern): C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\Data\LIBRARY
Proteus 7: C:\Program Files (x86)\Labcenter Electronics\Proteus 7 Professional\LIBRARY
Note: The ProgramData folder is often hidden. You may need to enable "Hidden Items" in Windows File Explorer. 2. Copy and Paste mq135 gas sensor library for proteus download upd work
Copy the .LIB and .IDX files from your download and paste them directly into the folder identified above. 3. Restart Proteus
If you had Proteus open, close it and restart it to refresh the component database. Simulating the MQ135 in Proteus To create your circuit, follow these steps:
Pick Component: Open the "Pick Devices" window (press 'P') and type "MQ135". Place the Sensor: Drop the sensor onto your schematic.
The Test Pin: Real-world sensors react to gas. In Proteus, the sensor usually has a "Test Pin". Connect a Potentiometer (POT-HG) to this pin.
By varying the potentiometer during simulation, you mimic the increase or decrease of gas concentration.
Wiring: Connect the VCC to 5V, GND to ground, and the Analog Output pin to your microcontroller's Analog-to-Digital Converter (ADC) pin (e.g., A0 on an Arduino). Troubleshooting "Library Not Found" If the MQ135 doesn't appear after installation:
Check File Path: Ensure the files aren't tucked inside a sub-folder within the LIBRARY directory. They must be in the root.
Run as Admin: Sometimes Windows prevents files from being written to the C: drive. Paste the files using Administrator privileges.
Hex File Requirement: Some advanced MQ135 models in Proteus require you to right-click the sensor, go to "Edit Properties," and attach a specific .HEX file provided with the download. Conclusion
Adding the MQ135 library to Proteus is a simple yet vital step for any IoT or environmental engineering project. By using the "Test Pin" method, you can effectively debug your code and ensure your thresholds for "Hazardous" air quality are functioning correctly before you ever pick up a soldering iron.
The MQ135 gas sensor is a critical component for simulating air quality projects, capable of detecting ammonia (NH3), nitrogen oxides (NOx), alcohol, benzene, and CO2 MQ135 Gas Sensor Library for Proteus: Download and
. Since Proteus does not include this sensor in its default library, you must manually download and install an external library file to use it in your simulations. 1. Download the MQ135 Library Files
To get the sensor working, you need three specific file types: (Library), (Index), and (Hex code for simulation). The Electronics (Latest Version) : Download the MQ135 Gas Sensor Library from their official repository. GitHub (Source) : You can also find the individual files on the satyamkr80 GitHub Repository The Engineering Projects (Alternative) : A broader Gas Sensor Library
containing multiple MQ-series sensors (MQ2 to MQ9) is also available. The Engineering Projects 2. Installation Guide for Proteus 7 & 8
Once you have downloaded and extracted the ZIP/RAR file, follow these steps to install it: Copy the Files : Copy the files from the extracted folder. Locate the Library Folder
: Paste these files into the Proteus installation directory. The path varies by version: Proteus 8.x
C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\LIBRARY ProgramData is often a hidden folder Proteus 7.x
C:\Program Files (x86)\Labcenter Electronics\Proteus 7 Professional\LIBRARY Restart Proteus
: If Proteus was open, close and restart it to refresh the component database. 3. How to Use the Sensor in Simulation
After installation, you must configure the sensor's internal code to make the simulation "work" and respond to inputs. MQ135 Gas Sensor Simulation in proteus - The Electronics
To get the MQ135 Gas Sensor working in Proteus, you must manually add the component files to the software's library folder. The sensor is not included in the standard Proteus installation. 1. Download Required Library Files
You can download the working library package (typically a .zip or .rar file) from trusted community sources like The Electronics or GitHub. The package must contain three essential files: MQ135.LIB (Library file) MQ135.IDX (Index file) MQ135.HEX (Simulation model file) 2. Install Files in Proteus Close Proteus
To make the sensor appear in your "Pick Devices" list, move the downloaded files to the following directory on your computer:
For Proteus 8.x: C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\Data\LIBRARY
Note: ProgramData is a hidden folder. Enable "Hidden items" in Windows File Explorer to see it.
For Proteus 7.x: C:\Program Files (x86)\Labcenter Electronics\Proteus 7 Professional\LIBRARY 3. Configure the Sensor in your Schematic
Once the files are moved, restart Proteus and follow these steps to simulate:
Pick the Device: Search for MQ135 in the component mode and place it on your canvas.
Attach the HEX File: Double-click the placed sensor. In the Edit Component window, find the Program File field. Click the folder icon and select the MQ135.HEX file you downloaded earlier. Simulation Pins: VCC/GND: Connect to power and ground. OUT: Connect to your microcontroller's analog pin.
Test Pin: Connect a Logic State toggle. Setting this to 1 simulates the presence of gas, causing the OUT pin to go HIGH.
| MQ135 Pin | Connect to | |-----------|--------------------------| | H (heater)| +5V | | A (analog)| Arduino A0 | | G (ground)| GND |
| Pros | Cons |
| :--- | :--- |
| Essential for IoT Projects: Enables simulation of Air Quality/Pollution projects without physical hardware. | No Real-Time "Sniffing": You cannot "blow" into your computer to test it. You must manually change values (slide the pot) to see the output change. |
| Visual Feedback: Most updated versions include a visual representation of the sensor "reading" or changing state. | Missing PPM Calculation: The raw library usually outputs voltage (0V-5V). The user must write the microcontroller code (C/C++ for Arduino or ASM for 8051) to convert this voltage into PPM (Parts Per Million). |
| Easy Integration: Connects easily with standard microcontrollers (Arduino, 8051, PIC, AVR). | Installation Issues: Sometimes requires placing files in specific LIBRARY and MODELS folders manually if the automatic import fails. |
There are two reliable sources (as of 2026):
Open Proteus → Library menu → Compile Library (or restart Proteus entirely).
Proteus locks library files when running. Close the software before copying any new files.
MQ135.IDX and MQ135.LIB to:C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\LIBRARYC:\Users\Public\Documents\Labcenter Electronics\Proteus 8 Professional\LIBRARY)UPD.TXT in the library folder, then run System > Check for Parts Updates.