Method Article

The Circadian Rave System: An Affordable, Open-Source, and Easy-to-Build System for Any Light-Based Experiments

DOI:

10.3791/68611

⸱

September 26th, 2025

 ,  ,  ,  ,  ,  , 
1School of Biochemistry, University of Bristol, 2School of Physiology, Pharmacology, and Neuroscience, University of Bristol, 3Neuroscience and Mental Health Innovation Institute, School of Biosciences, Cardiff University

In This Article

Summary

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Here we describe a protocol for building, programming, and running the Circadian Rave System, an Arduino-based light-emitting diode (LED) controller for managing multiple complex light regimes.

Abstract

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Precise control of lighting has broad applications in all biological sciences, but none more so than in circadian research. Life on Earth has evolved circadian clocks that are endogenous regulators of physiology and behavior that entrain to the 24-h solar day. To study the clock, researchers rely on experimental manipulation of either light or temperature to entrain circadian rhythms. Most laboratories currently use either commercially available or in-house-built lighting equipment to either mimic or disrupt natural day and night cycling. These systems offer limited programmability and precision, lack standardization, and, in some instances, affordability. To address these issues, we have developed the Circadian Rave System, a bespoke software and hardware package that allows the precise control of multiple independent light boxes. We have made the software open source, along with detailed hardware build guides, with the aim that future research can be standardized through the use of this system. To demonstrate the functionality of this system and its utility in circadian experiments, we measured longevity and activity of Drosophila in various light paradigms to show circadian synchronization and disruption through light manipulation. In conclusion, we have developed a standardized, scalable, and affordable lighting system that can be built in-house by any researcher with minimal prior knowledge in electronics or programming.

Introduction

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The precise control of light is critical in almost any experimentation involving animals. For the laboratory rearing of such animals, commercially available incubators can be purchased that have limited capacity for programming complex light and dark cycling regimes. The ability to program complex lighting regimes is necessary for many fields of study, but is critical in circadian research. The circadian clock, entrained to the solar day, is an endogenous oscillator that regulates changes in physiology and behavior from insects to mammals1. As such, circadian research has begun to permeate many fields of biological research, such as development2, immunity3, and human disease pathology4. Studies of the circadian clock rely heavily on using light or temperature to manipulate or even disrupt the clock through precise control of timing, intensity, and cycling5,6. Currently, there is a need for an affordable, scalable, and standardized system of controlling these variables for use in circadian experiments.

In addition to manipulating the endogenous circadian clock, various optogenetic tools have been developed that use specific wavelengths of light to control expression of transgenes in vivo and in vitro. For example, the immense genetic tractability of Drosophila melanogaster has resulted in many optogenetic tools that are available to researchers. For example, the light-sensitive shineGal4 variant of the Gal4 transcription factor can activate upon exposure to blue light and is a routinely used tool by many labs7,8,9. Researchers tend to achieve light changes by either manually switching lights on or via laser induction, but both methods can introduce logistical and technical constraints during experimental design and implementation. The ability to program the start, stop, specific wavelength, cycling, and intensity (dosage) of light would be of extreme benefit.

To give researchers full control of lighting conditions, we have designed the Circadian Rave System (CRS). This is an alternative, affordable, and do-it-yourself (DIY) system that can be built and adapted by researchers, allowing for full customization of lighting regimes. The system relies on an Arduino microcontroller that can control up to six independent LED channels, making the system affordable and scalable. Microcontrollers such as Arduinos have been successfully used to make many pieces of DIY lab equipment because of their ease of use10,11,12. This system can be used in existing incubators and has been successfully tested at typical experimental temperatures, providing a wide range of functionality (4-37 °C). Users can program the CRS via the bespoke, open-source software that has been developed for multiple operating systems. The software has an easy-to-use user interface, allowing for the programming of complex light regimes to more closely mimic solar light patterns. These custom light regimes can be created, saved, and then later loaded onto the microcontroller, so a set of previously generated light regimes can be used, saving time during experimental setup. Once the device has been programmed, it can be disconnected from the computer, which enables scalability compared to conventional systems that require dedicated computers to run lighting regimes. To test the reliability of the CRS, we performed lifespan and activity analysis on Drosophila exposed to various CRS-generated light regimes. The CRS was found to reliably execute multiple lighting regimes continuously for months.

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Protocol

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1. Building the CRS

NOTE: The CRS was designed to be built in-house by researchers, and as such, all components are commercially available from multiple vendors (Table of Materials). The exceptions are the printed circuit boards (PCB) that must be produced commercially by PCB printing specialists or by contacting the authors. For commercial production, the Gerber files are in the GitHub repository (@Trincatalyst/CRS/Hardware/gerber/microcontroller_PCB). University engineering departments typically have PCB printing facilities. Below are detailed instructions on how to build, quality check, and program a single CRS unit.

  1. Assembling the circuit
    1. Top-mount solder the electrical components onto the microcontroller PCB. The Arduino A1 connector pins are the only bottom-mounted components. The placement of components onto the PCB corresponds to the letter-number labelling on the PCB (Table 1). Test the soldered connections with a multimeter.
    2. Insert the Arduino into the bottom side of the assembled PCB using the A1 connections.
    3. Solder the LEDs or LED strips to a 12 V cable wire (recommended to be at least 1 m long) and screw the positive and negative ends of the 12 V wire to the PCB terminal block, and then secure in place with a screwdriver.
      NOTE: The custom LED PCBs (@Trincatalyst/CRS/Hardware/gerber/LED_PCB) can be used as an alternative for LED strips; each LED PCB houses a single LED. This offers the advantage of using LEDs with known and discrete emission spectra.
    4. Repeat step 1.1.3 for each of the six channels.
      NOTE: If using LED strips, each LED channel can handle up to 400 mA of current, which amounts to a maximum of 20x LEDs (20 mA each). Therefore, the system was designed to be used with 5 V LED strips with up to 20 LEDs attached to each of the six output channels.
  2. Building CRS enclosure
    1. Enclose the CRS (PCB and Arduino) to ensure the safety and longevity of circuitry.
      NOTE: The GitHub repository has a 3D printable enclosure successfully printed in both PLA and ABS, protecting the device (@Trincatalyst/CRS/Hardware/CRS_enclosure).
  3. LED enclosures
    1. Either integrate the LEDs directly into incubators, replacing pre-existing lighting setups, or place them in bespoke enclosures that can be stacked into a single incubator (Figure 1).
    2. Bespoke enclosures offer the benefits of increased scalability, affordability, and reduced space requirements. The recycling of lab plastics, such as tip boxes, can reduce costs further (Figure 1D). "Blacken out" these recycled boxes with insulation tape to prevent light leakage. However, for a more durable solution, machine enclosures from acrylic, which have been successfully tested (@Trincatalyst/CRS/Hardware/LED_enclosure).
      NOTE: Make sure to test that the enclosure is lightproof, as leakage could confound other nearby experiments that are running in parallel, and test that the LEDs do not increase internal container temperature if using LED strips in a small container.
  4. Installing firmware on CRS
    1. Download the CRS firmware that consists of two files: the definition.h and the CircadianRaveSystem.ino files. Both can be found in the GitHub repository (@Trincatalyst/CRS/Software/PCB_firmware).
    2. Download and install the Arduino integrated development environment (IDE) software from www.arduino.cc/software.
    3. Connect the Arduino to the computer via a USB lead and within the Arduino IDE select the correct Arduino communication (COM) port and establish a connection.
      NOTE: The Arduino does not need to be connected to the PCB circuit during firmware configuration.
    4. Next, go to File > Open and select the folder containing the definition.h and CircadianRaveSystem.ino files.
    5. Once a new IDE window opens, click Verify and then upload. This will install the firmware onto the Arduino. The output terminal should display a completion output.
    6. Disconnect the Arduino, which is now ready to be used as a CRS.
  5. Powering on the CRS
    1. Power the CRS by inserting a 5 V power supply with a 2.5 A capability into the PCB power barrel.
      NOTE: Each LED channel is designed to handle up to 400 mA current, which amounts to a maximum of 20x LEDs at 20 mA each. The system was designed to be used with 5 V LED strips with up to 20 LEDs attached to each of the six output channels. The PCB is equipped with an overvoltage and overcurrent protection device, which triggers at 3 A continuous current or if the user plugs in a power supply voltage exceeding 6.2 V the power will be cut.
  6. Quality testing the CRS
    1. Prior to running experiments with the CRS, test that each LED/LED strip connected to the CRS works reliably for at least 2 days. To do this, run the CRS_test_profile.txt file found in the GitHub repository (@Trincatalyst/CRS/Software/Test/CRS_test_2days.txt) or design a light regime within the CRS software. The loading profiles step 2.6 has instructions on how to run the CRS_test_2days.txt file.

2. Running an experiment

  1. Follow the next steps to install the CRS software that allows for the programming, running, and checking complex lighting regimes.
  2. Installing the CRS software
    1. Download the CRS software directly from the GitHub repository (@CRS/CRS_software).
      NOTE: The software has been thoroughly tested and is fully compatible with the following operating systems:
      For Windows 10 and 11, download @Trincatalyst/CRS/Software/bin/Circadian-Rave-System-v1.2-win.zip.
      For macOS Ventura, download @Trincatalyst/CRS/Software/bin/Circadian-Rave-System-v1.2-win.zip.
    2. Locate and open the downloaded CRS software. This will initiate installation, and once complete will be ready for use.
      NOTE: Changing the location of the software to a more accessible folder is recommended.
  3. Connecting to the CRS device
    1. Power on the CRS.
    2. Use a Future Technology Devices International (FTDI) cable to connect the CRS device to a computer with the CRS software pre-installed.
    3. Open the CRS software, then click the Select Port dropdown menu in the View tab, select the CRS, and the six LED tables should all update when connected. If experiments were running, each profile would update accordingly. Each CRS LED is now ready to be programmed.
  4. Programming CRS
    ​NOTE: The CRS was designed with circadian experiments in mind, and as much relevant functionality as possible have been added. For example, a typical complex experiment may require light entrainment spanning days, followed by darkness for a few days, and then a further re-entrainment.
    1. Fully program the experiment in the CRS prior to experimentation. Program each of the LEDs/LED strips in each of the six output channels independently using the LED tabs one to six (Figure 1B). Find a graphical representation of programmed lighting regimes within each LED tab and use it as a reference during programming.
    2. Lighting regimes have been split into three distinct steps, and each can have a light intensity and duration set. Steps 1 and 3 do cycle and can act as synchronizing steps between different LED channels, i.e, allowing the loading of samples into the LED enclosures at different times. Repeat step 2 using a cycling toggle, which is typically programmed to span a 24 h period.
    3. By toggling the light intensity and durations of T1, T2, T3, and T4, complex light regimes are created. T1 and T3 act as intermediates allowing for the ramping up and down of light intensity, more closely mimicking natural day and cycling of light. Once a program has been set, save and run.
      NOTE: When a programmed light regime is running, the graphical regime will update accordingly, and the View tab will update.
  5. Storage and loading of light profiles
    1. For light regimes that are repeated between experiments, save the profile using the Save button, which will convert the profile into a CRS-readable txt file.
    2. Load previously saved profiles into CRS using the Load button, expediting future programming.
  6. Loading and running profiles
    1. For testing, run the tester profile for each LED strip simultaneously. Go to the LED tabs, click on the Load profile, and click on the CRS_test_profile.txt.
    2. Click Program to upload the profile into the CRS. The graph should update along with the profile statistics.
    3. Click Start, and the graph will live update with the progress of the run. Repeat this for all six LED profiles.
  7. Disconnecting from CRS hardware
    1. Disconnect with the Disconnect button located in the View tab. Now, remove the FTRI lead safely.
  8. Checking the progress of experiments
    1. To check the status of light regimes whilst the CRS is running, open the CRS software, then in the View tab, click the Select Port dropdown menu, and select the CRS. The view tab has all the current information of all six LED tabs. Disconnect as previously described.

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Results

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CRS overview
The CRS is a combination of hardware and software that allows users to program complex lighting regimes for up to six independent LED strips per device (Figure 1A). The software can be easily downloaded from the GitHub repository (@Trincatalyst/CRS/Software) and within the main page of the software, further detailed instructions of use can be found (Figure 1B). The hardware was designed to be affordable and easy to build by anyo...

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Discussion

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To investigate how light influences physiology and behaviour, complex lighting schedules are required, typically with multiple conditions running in parallel. Precise control of the timing and intensity of light exposure is also key for reliable and reproducible data in these circadian experiments. Light cycling can be achieved with commercially available incubators or LEDs linked to mechanical timer plugs. However, these systems offer limited or no ability to program complicated light cycling parameters, and often the u...

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Disclosures

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The authors have nothing to disclose

Acknowledgements

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We would like to thank Dr Edgar Buhl and Prof James Hodge for the use of the DAM system and setup guidance. We would also like to thank Prof Paul Martin for his support and guidance in developing the CRS. This work was supported by a BBSRC grant BB/T001984/1 awarded to Prof Paul Martin.

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
0.1 µF Ceramic CapacitorFarnell 2507749Quantity = 2
100 kΩ axial THT resistor 250 mWFarnell 3951804Quantity = 6
100 Ω axial THT resistor 250 mWFarnell 3496799Quantity = 6
1 µF Ceramic CapacitorFarnell 2819603Quantity = 2
2.54 mm pitch Through Hole Header Horizontal Mount - FTDI Farnell 3756363Quantity = 6
Arduino Headers 10 wayFarnell 1593417Quantity = 1
Arduino Headers 3 wayFarnell 1593412Quantity = 1
Arduino Headers 8 wayFarnell 1593416Quantity = 1
Arduino Uno R3Arduino A000066Quantity = 1
Barrel JackFarnell 224959Quantity = 1
Circadian Rave System PCBMartin LabMartin Lab1 (120 strips or 1 LED component with a LED PCB)
Diode Farnell 4245041Quantity = 1
eFuse Circuit ProtectionFarnell 4178928Quantity = 1
FTDI CableFarnell 2419945Quantity = 1
LEDsRS 855-5933120 strips or 1 LED component with a LED PCB
POWER SUPPLY 15WFarnell 2815857Quantity = 1
Screw Terminals Farnell 2314973Quantity = 6
ST Microelectronics N-Channel MOSFET STP30NF10Farnell 9946403Quantity = 6

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Tags

Circadian ResearchLight Based ExperimentsCircadian RhythmsLighting ControlOpen Source HardwareDrosophila ActivityLight ManipulationCircadian SynchronizationAffordable Lighting SystemBiological Clocks

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