Connected Studio Warning Light

In this Instructable, we’re going to build a very modern take on an iconic piece of studio equipment: a smart on-air warning light that responds to the Robin room reservation system.

This project started life as a practical solution to our occasional need for quiet in a busy office of creatives while recording Uncorked Studio’s podcast, With Intent. To read the whole back-story, and find out more about Uncorked Studios, take a look at our blog post.

Bits and Pieces

1. Sandies 343-110 3-sided studio warning light
2. Raspberry Pi 2B
3. USB A to micro B cable and USB power supply
4. 8GB+ SD card
5. USB keyboard
6. HDMI cable and monitor
7. USB Mini WiFi Adapter based on Realtek 8188CU
8. 12V power supply that can deliver at least 1.25A. We recycled an old laptop power brick that can deliver 12V/5A.
9. Pimoroni ExplorerHat Pro expander board
10. 12V G4 26 LED lamp assembly
11. Murata 78SRH-5/2-C DC-DC converter
12. 2x 2N2222A/PN2222A NPN Transistors, TO-92 package
13. 2x 10K resistors (leaded)
14. Assorted breadboard wire
15. 4x Delrin screws, nuts and standoffs

Initial assembly

• Plug the ExplorerHat expander board into the RaspberryPi
• Plug a USB keyboard into any of the USB ports
• Plug the HDMI cable into the RPi and connect a monitor
• Insert the USB WiFi dongle into any available USB port

At this point, don’t power the board up. For the first couple steps in this Instructable, we’ll power the RaspberryPi from the USB power supply and cable, connected to J1 (marked “PWR IN”). After the board is booting and configured, we’ll mod it to run off the 12V power brick.

Raspbian is a Debian Wheezy variant built for the RaspberryPi. For this project, we installed the stock Raspbian build, configured it for command-line only access, and added a few packages to support the additional hardware we installed.

To get the RPi booting a fresh copy of Raspbian, follow the instructions for NOOBS Setup, stopping at “FIRST BOOT” step 5 (raspi-config). Since this application requires the RPi to understand our current time and time zone, we’ll make a few modifications to the standard config before exiting the utility.

Get some more room

From the main menu, select “1 Expand Filesystem” and follow the prompts to make some more space on the SD card.

Locali(s/z)e Raspbian

By default, Raspbian is configured for the UK, including time zone and keyboard layout. If you happen to live elsewhere, a little reconfiguration is required. Clayton Smith wrote a very concise guide to Making the Raspberry Pi a little less British. (His instructions assume you’re starting from the command prompt; to get there, exit out of raspi-config and log in to a shell.)

1. From the raspi-config main menu, select “4 Internationalisation Options”
2. Select “I1 Change Locale”
3. Deselect en_GB.UTF-8 and select the locale appropriate to your location. We chose en_US.UTF-8.
4. Select OK to return to the main menu
5. Once again select “4 Internationalisation Options” and then “I2 Change Timezone”. Walk through the screens to select your time zone, and save to return to the main menu.
6. Once again, select “4 Internationalisation Options” and then “I3 Change Keyboard Layout”. Select the correct keyboard layout for your system. Save, and return to the main menu.
7. It’s probably a good idea to change the default password on your RPi at this point. Select “2 Change User Password” and follow the prompts.
8. Save, and then exit raspi-config by selecting “Finish”.

Log in to the RaspberryPi using the password you set in step 7 above. (Default user is ‘pi’, password is ‘raspberry’.)

Update Raspbian and install a few essentials

It’s a good idea to update Raspbian to the latest build, and then install a few essential tools we’ll need later. Given all that may have been installed, a reboot is a good idea.

sudo apt-get update -y && sudo apt-get upgrade -y
sudo apt-get install -y git build-essential vim tmux curl
sudo reboot