Introduction: Phone Quarantimer for Digital Minimalism!

Too many times I'd grab my phone to check the weather and end up in a social media spiral. I needed a phone quarantimer. :)

This is a phone stand that will light up when you place your phone down. In addition, it keeps track of how long you leave it resting.

Build multiple to find out who uses their phone the least among the family! Or use it yourself to track how long you've left it alone! Everyone loves positive reinforcement.

I'd been dreaming of making a Phone Quarantimer (Quarantine Timer) for my own use. I've tried blocking apps but wanted a physical place to put my phone. In addition, it's easy for my parents and brother to use - no extra app required. Instead, we use a photoresistor to detect the phone's presence when it blocks light from above.

Added bonus: I'm incentivized to rest my phone in a dedicated spot. This means I am less likely to lose it!

  1. March - I had a vague idea that I needed to limit time spent on the phone. Lock it in a box? With a timer?
  2. April - Sketched a lot and prototyped my idea on a breadboard. Didn't do much else besides spend time on my phone. :(
  3. May 19 - Saw this Instructables Contest and was inspired to make it robust! Spun up a quick n' dirty PCB that same evening. We need this fast!
  4. May 20 - Ordered PCBs and waited.
  5. May 29 - Solder and assemble.

I was in a rush to build this, and used as few components as possible. I hope you're inspired to build one too! I think it's a great beginner project to learn PCB design and Arduino. You can also embellish and add additional features! I myself hope to add some exciting soon as I put my phone down. ;)


  • one led
  • 10K resistor (any compatible value for photoresistor pull)
  • 220 resistor (any compatible value for the led)
  • Arduino Nano (Uno can substitute)
  • display - I used a 128x64 OLED


  • female headers
  • (4) M3x20mm standoffs
  • (4) M3 screws

Step 1: (Optional But Recommended) Breadboard Your Circuit

Though I ported my final project to a PCB, you can easily use a breadboard instead. Just tuck everything in a box, with holes to charge the Arduino and let the photoresistor peek out.

Breadboarding will also help ensure your connections and hardware are good to go.

Step 2: Design a PCB

Designing a PCB involves:

  1. Making a schematic
  2. Laying out the board

I'll drop both files I designed below. This is a pretty simple circuit and can be modified as you desire.

My phone is 3 inches wide and 6 tall. I adjusted my board dimensions to allow me to rest my phone on standoffs on 4 corners.

Regarding the actual circuit, we have very few components:

  • Arduino Nano
  • led to confirm phone presence
  • 2 resistors
  • photoresistor to detect the phone
  • OLED display to show elapsed time

I ordered my PCBs from JLCPCB. If you do not want to wait for a third-party, you can easily use matrix board for your final project!

Step 3: Assemble and Solder!

If you have female headers, solder them on the footprints for the Arduino Nano and OLED.

I find them very convenient; rather than directly soldering an Arduino onto the board, you can solder the female headers in. The Arduino is removable in case it fries or you want to reuse it.

  • The 10K resistor should be on the right, connecting to the photoresistor. This is a pulldown resistor so we use a high resistance value.
  • The 220 resistor simply goes in series with our led to limit current.
  • Our 128x64 OLED uses I2C to communicate, so it only requires 2 lines: SCL and SDA.

Solder everything on, check for shorts, and power it up!

Add on standoffs - I used M3X20mm. These are 20mm tall, so as to allow clearance. We don't want the phone to touch the Arduino or OLED! You can use standoffs or even plastic straws at any height above 20mm.

Personally, I am okay with a bare board. Understandably though, a cover would prevent damage. I am afraid of my phone smashing the photoresistor!

You can find a piece of cardboard the same dimensions as the PCB, cut a hole where the photoresistor peeks out, and you'll have a cover! Wood or a custom 3D printed case work too.

(Pictures from Fusion. You can export your Eagle PCB files to Fusion360. Both software are under Autodesk.)

Step 4: Upload Arduino Code

Here are some detailed images of the actual thing.

In this code, covering a photoresistor will trigger an led to light up and timer to appear on the display.

Libraries you may need:

You can make some personal modifications:

  • Adjust the threshold of (photocellReading < 300) according to your own room light levels.
  • I've triggered the led to turn on if the phone is present. You can do the opposite and turn it off when you place your phone on top.
  • I also used seconds in my timer. You can count by minutes or hours if you so wish. :)

Step 5: You're Done!

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