Open source

Build it yourself

X-Tag compatible Arduino projects, plus 3D printable spare parts and other useful parts.

XOpen is our open source project: a target, an alignment cross and a support remote, all built around an Arduino Nano. The target and the cross read X-Tag shots with an infrared receiver; the remote sends support commands with an infrared LED. Code and wiring diagrams are on GitHub; assembly calls for basic electronics skills and tools.

Cults3D has the 3D printable files instead: spare parts for X-Tag devices and other useful parts.

Code and wiring diagrams on GitHub

The xopen repository contains the sketches (the Arduino programs), the wiring diagrams and the XOpenIR library. Choose a project and follow the instructions to assemble it and upload the code.

Open xopen on GitHub →

3D models on Cults3D

Find X-Tag files to 3D print on Cults3D: spare parts and other useful parts.

Visit the Cults3D page →

The three projects

Target

Difficulty: Easy
Time: One hour
Cost: About €10

The TSOP4840 receiver detects shots from the replica, and an LED signals each hit. Three digital outputs can control external indicators or mechanisms through suitable driver circuits. The serial monitor shows one line per hit.

Counts hits and measures the replica's actual rate of fire
Three digital outputs for indicator or actuator circuits
Pins and pulse length in the first lines of the sketch

What you need

Qty	Part
1	Arduino Nano (ATmega328P)
1	TSOP4840 infrared receiverthe 40 kHz version
1	100 Ω resistor + 4.7 µF capacitor
1	5 mm red LED + 330 Ω resistor
1	Normally open push button

Wiring

Pin	Signal
D2	TSOP4840 output
D5	Hit LED
D6, D7, D8	Outputs pulse on each hit; duration is set in the sketch
D4	Reset button

Sketch →Wiring →

Calibration cross

See where the beam lands

Difficulty: Medium
Time: An evening
Cost: About €25

Five receivers in a cross, each with its own LED, show where the beam lands. You can see how it spreads and adjust the replica’s zeroing, without a computer.

Five independent channels, each with its own LED
Summary of the percentage of hits registered by each sensor
Set sensor spacing using the guidance in the wiring notes

What you need

Qty	Part
1	Arduino Nano (ATmega328P)
5	TSOP4840 infrared receiver
5	100 Ω resistor + 4.7 µF capacitorone per sensor, not one for the whole cross
5	5 mm LED + 330 Ω resistorgreen in the centre, red on the arms
1	Normally open push button
1	Perfboard or a 3D-printed mount

Wiring

Pin	Signal
A0 … A4	The five TSOPs: centre, up, down, left, right
D8 … D12	The five LEDs, in the same order
D2	Summary button

Sketch →Wiring and distances →

Remote

Respawn, ammunition and healing on three buttons

Difficulty: Easy
Time: An afternoon
Cost: About €10

Aim the infrared emitter at the headset and press the button for the command you want to send. Use the project as the basis for a respawn point, ammunition crate or medical station in your games.

Respawn, full ammo, configurable heal
Support commands only: it does not shoot and does not take health away
Range of a few metres in the basic configuration

What you need

Qty	Part
1	Arduino Nano (ATmega328P)
1	940 nm infrared LEDTSAL6200, TSAL6400 or SFH4545
1	390 Ω resistorLimits LED current; follow the project wiring diagram
3	Normally open push buttons
1	4×AA battery holder or USB power bank

Wiring

Pin	Signal
D3	Infrared LED with its 390 Ω resistor
D4, D5, D6	Respawn, ammo and heal buttons

Sketch →Wiring →

Getting started

01
Parts
Get the components listed in the wiring diagram. Use the 40 kHz TSOP4840 receiver: the more common TSOP4838 is a 38 kHz part and is not an equivalent replacement.
02
Library
Copy the XOpenIR folder from the repository into the libraries folder of your Arduino sketchbook.
03
Upload
In the Arduino IDE, select the Nano board and the correct processor, then upload the sketch. Some clones need “ATmega328P (Old Bootloader)”. Set the serial monitor to 115200 baud.

Using the devices in games

Before using a DIY device in a game, check with the organisers. A headset locked with a password ignores respawn, ammunition and healing commands from unauthorised devices. The lock covers these commands, not targets.

Before you build

These are hobby projects to assemble and check yourself, without a warranty or individual assembly support. Follow the wiring diagrams and component limits. The remote’s infrared LED is not the certified X-Fire emitter: keep to the specified setup and do not aim it at anyone’s eyes.

Frequently asked questions

Do I need to know how to program?

No, to start you just upload the sketches as they are. To change pins, values or functions you need some Arduino experience; the settings you can change are near the top of the code.

Can I use a TSOP4838 instead of the 4840?

Better not. The TSOP4838 is tuned to 38 kHz, while X-Tag transmits at 40 kHz, so it would pick up hits less reliably.

Will it run on an ESP32 or a Raspberry Pi Pico?

The sketches are written for the ATmega328P in the Arduino Nano. Running them on an ESP32 or Raspberry Pi Pico requires adapting the code to that platform.

How far apart should the arms of the cross be?

Spacing depends on the beam width and test distance. Use the guidance and table in the cross’s wiring notes when building the mount.

Can I use the remote during a game?

Only if the game rules allow it, because it sends support commands. A locked headset ignores them.

Are more projects coming?

The repository contains these three projects. If you build one and want to share an improvement, you can submit a pull request on GitHub, that is a proposed change.