Make Powered Projector Screen “Smart” With WiFi Smart Switch

Introduction: Make Powered Projector Screen “Smart” With WiFi Smart Switch

Have a powered projector screen for your media center? Ever wish you could control it with voice commands? I’m going to demonstrate how to add Alexa (and other smart assistant) support to control your screen. All parts can be found online for less than $25.00. Links are for example only. You may be able to find some parts cheaper on other sites or at your local electronics store. I paid less than $0.50 for each DB9 connector at my local store.




  • Soldering Iron with Solder
  • PH1 Phillips Screwdriver
  • Rotary Tool
  • 3D Printer (Optional)

Step 1: Identify the Parts on Your Circuit Board.

To wire the power for the Smart Switch to the existing power in the screen control circuit board we will need to identify the transformer that reduces the 110v AC to ~12v AC (or DC). The side coming from the wall will be 110v and the other side will be ~12v. The actual output voltage will be on the label.

You will need to identify the up and down switches as well. Use a flat screwdriver to bridge the leads on the switch to close the circuit and figure which leads control the screen motors.

Step 2: Prepare DB9 Connectors

Use around 6-8” of the CAT6 cable on each side (or other 20-24 gauge wire). Remove six strands from the jacket. We will use the colors to identify which colors go where.

Plug the two sides together and solder the wires to the leads so the colors match on both sides.

Step 3: Attach DB9 Wiring Harness to Screen Circuit Board.

Cut a hole in the screen control housing for the female DB9 connector with a rotary tool and fix in place with two #4 x 1/2” machine screws. Predrill the holes to prevent cracking the plastic. I had to drill a hole in the circuit board to thread the wires to the back of the board.

Separate the wires into sets of two and solder one set to the 12v power and one set to each switch.

Step 4: Assemble the Smart Switch in the Plastic Housing.

I used a 3D printed box to hold the switch board. Cut a hole and affix the male DB9 wiring harness where it will not interfere with the board. I was able to grind the board down slightly to fit inside the lid of the box.

Attach the power wires to the 7-32v clamp connectors and tighten with Philips head screwdriver.

Attach one switch pair to each relay. Attach one wire to the center “Common” terminal and the other to the “Normally Open” terminals. The circuit is open until a signal causes the relay to close the circuit for a second, lowering or raising the screen.

Step 5: Setup Smart Switch With WiFi and Alexa

Download the eWeLink app and follow the instructions to connect to WiFi and sync with Alexa. In the Alexa app, name the channel that controls the up switch “Screen Up” and the other “Screen Down”. There will be a third device in the list that controls both simultaneously. Name it something you can remember that Alexa won’t mistakenly use.

Plug the switch in to the screen control box and say “Alexa activate Screen Down”. To stop mid action just activate the opposing command.

Step 6: Siri Setup

To make it work with Siri and add iOS Widgets we will use the eWeLink App and the Shortcuts App for iOS.

  1. In the eWeLink App go to the "Scenes" tab at the bottom of the screen.
  2. Tap on the "+" at the top left of the screen.
  3. Add an "If" trigger.
  4. Select "Tap to perform".
  5. Add a "Then" action.
  6. Choose "Smart Device".
  7. Select your 2 channel WiFi switch.
  8. Select your action, in this case "Screen Down".
  9. Choose "ON" and hit "Save".
  10. Hit "Save" until you get back to this screen and hit "Save" one more time.
  11. Enter the phrase you want to say to Siri in order to initiate the selected action, in this case "Put The Screen Down".
  12. Back to the first image, tap on the "Add to Siri" button at the top left portion of the screen.
  13. Add your new scene to Siri.
  14. Here you can change what you have to say to Siri to activate your command. Change it if you want and tap "Add to Siri"

You can now use "Hey Siri, put the screen down." to lower your screen. It's a little more natural sounding that "Alexa, activate Screen down."

Repeat 1-14 for the other "Screen Up" switch.

Check out the next step for how to add a widget to your iOS homescreen.

Step 7: Add a Widget to Your IOS Home Screen

In this step we will add a widget to our iOS home screen so we will always have easy access to it when the significant other falls asleep during the movie and we don't want to wake them up by yelling at our robot to put the screen up. (Especially if said SO is grumpy when they get woken up.)

  1. Hard press on the home screen to put it into "Jiggle Mode" ad hit the "+" in to top left portion of the screen.
  2. Scroll down and select ""Shortcuts".
  3. Stick with the default "Shortcut" and tap on "+ Add Widget". Don't worry if it's not the shortcut you need. You can edit it later. Repeat steps 1-3 for the other direction.
  4. Hard press on the widget you would like to change to bring up the options menu.
  5. Select "Edit Widget".
  6. Tap on the name of the shortcut to be changed.
  7. Choose the new shortcut to use in the widget.
  8. You can now hard press on the widgets and move them around the Home Screen or for easiest accessibility, move them to the Today View screen by swiping right from the home screen or lock screen.

Step 8: Seal Housing and Connect to Screen Controller.

Once you have confirmed everything works you can seal the housing box with super glue.

Step 9: Plug Smart Switch Into Projector Screen Control Box and Enjoy

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    Reply 1 year ago

    You’re right, that does work in a handy commercial package. For me it’s all about the process and doing it real DIY. It’s fun and satisfying to figure out how something works and bend a product to meet my needs. In fact I usually overcomplicate most of my projects. It’s not about easy. Easy is boring!


    Reply 1 year ago

    only if you already have wireless. this is making a wired switch wireless + home automation.


    2 years ago

    I added instructions on how to set up voice commands for Siri on iOS and add a widget to you Home Screen/Today View.