Adding real-world devices to the sim racing experience has been the norm in PC-based sim racing games since SimHub released its first version in 2016. PC sim racers have long enjoyed all of the realism and functionality of real-world tools to bridge the gap between the real and virtual worlds. Now, Gran Turismo 7 users can enjoy the same experience.
Building Your GT7 Tachometer Display
A tachometer or tach is a gauge that measures and displays engine speed in RPMs (revolutions per minute). As sim racers, why do we care about RPMs? When we are racing at the limit, knowing the engine’s RPMs helps optimize gear changes, helps identify shift points to improve lap times by making full use of the engine’s power band.
Its true, Gran Turismo 7 includes an on-screen tachometer. But there is something about adding a real-world tachometer to your sim racing experience that bridges the gap between the virtual and real worlds, bringing immersion just a little bit closer to real life. When racing, I always glance at the tach when trying to push the limits of my car.
What are the benefits of using a real-world tach for sim racing?
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Shifting at the optimal RPM: Shifting just before reaching the redline allows for smoother acceleration and prevents engine over-revving.
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Driving efficiently: Maintaining RPMs within the ideal power band helps achieve faster lap times.
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Improving consistency: Maximizing RPMs helps develop precise shifting habits, leading to more stable and repeatable performance.
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Preventing engine damage: Yes, even in sim racing, you over-stress the engine, especially during endurance races.
Buying a Pre-built Tachometer for Sim Racing
If you're new to electronics or DIY builds, this project can be overwhelming. It involves sourcing the right components, some light soldering, some troubleshooting, and 3d printing. For many people, especially those who just want something that works out of the box, buying a pre-built version from Amazon, Etsy, or eBay might be a better solution.
A quick search for Tachometer for Sim Racing on Etsy, eBay, Amazon, and Aliexpress shows similar units for sale. They all share a common use of SimHub for compatibility with Gran Turismo 7.
Many of the sellers offering these devices are hobbyists just like us, and your purchase helps support the maker community while saving you time, money, and frustration. You can buy a pre-built, ready-to-run tachometer that requires no soldering or sourcing of materials. These plug-in tachometers come complete with a tachometer, Arduino, and all of the wiring described in the DIY section of this section.
Most of my DIY projects have easily cost me at least twice as much as buying a pre-built solution.
DIY Analog Tachometer
I am not the first to display data from a sim into a real-world tachometer. My experiences are based on those who have completed this process over the years using tutorials, YouTube videos, and forum posts, into a step-by-step tutorial. This is the process I used to create my tachometer for GT7 and describes any challenges I had along the way.
One of the biggest issues people have is that there are so many tachometers available that they have problems getting them to work with SimHub. Additionally, whatever tachometer you use, you need to make sure that the high-end range of the tach meets your needs for your sim racing environment. These are the two that I use for my sim racing.
Parts List
• Tachometer
• Arduino Uno
• 2.2k Resistor
• Tip120 Transistor
• Diode IN5349B
• Strip Vero PCB board (8x9)
• 12V 500mA Power supply
• Project Wire
• 3D Case
Tools
• Solder
• Soldering Iron
• Wire Cutter
• Wire Stripper
Print the 3D Case
You can use this STL case on MakerWorld or search for Arduino Uno and motor shield case on any of the 3D printing sites and print one that meets your needs. Don’t skip this step because there will be exposed wires, and you need to take some basic precautions by housing your project in a case. You can download the STL used in this chapter at the following URL:
https://makerworld.com/en/models/1516473-windsim-arduino-uno-and- motor-shield-box 
Official SimHub Arduino Market Tach Support Page
I used the ‘official’ Arduino After Market Tach support page for much of my build process and credit goes to the original makers. The next section documents my build and any issues I had using up-to-date links and current software.
Getting Started
Adding a real-world tachometer to show race sim information can be a rewarding project, but keep in mind that it involves some technical steps and troubleshooting. If you have experience with hardware setup, programming, or similar projects, you'll likely find it manageable with some guidance.
I used the Arduino Uno for my microprocessor; the finished project is configured using SimHub software.
Familiarize yourself with the TIP120 pinouts. These instructions will reference the placement of connections by their Pin numbers.
This is the complete project diagram I used to guide me through the build process.
Make the Connections
I broke down each step into a separate image to make the build process easier to follow. The numbered list corresponds to the item numbers in the diagram.
- Solder the TIP120 to the PCB board. Notice there is at least one spare rail to the left of Pin 1. You will need this rail for Step 2.

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Solder a 2.2K resistor to the rail connected to Pin 1 (left) on the Tip120, and the other end of the 2.2K resistor to an empty rail to the left of Pin 1.

- Solder the white-stripe end of the diode to Pin 2 (middle) and the other end of the diode to Pin 3 (right) rail. This is an important placement of the diode; confirm that the white stripe is connected to the rail of Pin 2.
- Solder a wire from the far left rail (the one connected to the 2.2K resistor) to Pin 9 on the Arduino Uno, and another wire from the ground rail of your breadboard to GND of the Arduino Uno. 
- Solder the 12V positive lead to the Pin 2 (middle) rail and the ground from the 12V power source to the ground rail. 
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The remaining wires are from your tachometer. Make the following connections.

Mounting the Electronics
Once you’ve completed the wiring, mount the Arduino Uno and PCB board into a 3D printed case and continue to SimHub Configuration.
SimHub Setup
The setup and configuration of the tachometer is through SimHub. If you haven’t already configured your firewall to work with SimHub and Gran Turismo 7, then read my previous article on Hackernoon, How to Set Up Simhub With Gran Turismo 7. You only need to set up the firewall once to use any SimHub functionality with GT7.
Getting Started
Plug your completed tach into an available USB port on your Windows PC. Open SimHub and select Arduino [1]. From the Arduino main page, select the My Hardware[2] tab.
Select the appropriate option for the number of Arduinos you are adding and click the Open arduino setup tool [3].
Select Arduino Uno (ATMega328p) [4] from the Board popup menu. Select the Arduino serial port [5] your Arduino is using and enable the box [6] that you understand you are overwriting any firmware on your Arduino.
Don’t forget to name your device in the Device name [7] text box. If you are adding several Arduino’s creating a meaningful name will help you when managing multiple devices.
Scroll down through the SKETCH SETUP list and switch the Tachometer button [8] to ON. Notice the Tachometer signal pin. (This is the same pin you connected in Step 4 of the Make the Connections section earlier in the DIY Tachometer section.)
Click the UPLOAD TO ARDUINO [10]button to load the Tachometer firmware to your Arduino Uno.
After the upload is complete, close the Arduino setup tool window.
Configuring the Tachometer using SimHub
From the SimHub main page, select Arduino from the list on left and then the Gauges tab.
This opens the TACHOMETER page, where we can make some basic changes for your tachometer. The first one is the Max tachometer RPM. Change this to match the maximum RPM of your tachometer.
Adjust the number of cylinders according to your environment.
I leave all of the other settings at their default settings. If you need to fine-tune your tachometer, you can do this in the ‘Advanced calibration’ menu.
On the TachometerAdvanced calibration page, you can fine-tune SimHub with your tachometer. You can do this by Testing the value at each RPM range, and adjusting the Needle Offset to match the values on your tachometer.
You need to have SimHub open and set up to run Gran Turismo 7 from the list of available games. Your tachometer starts displaying data when you start your race in GT7.