Wake up Lamp

February 16, 2022

I made a dawn simulation lamp to help me wake up.

A black box with a translucent white top. There is a light shining through the top and there is one button and one rotary knob. The front has a red LED display showing 17:00.


Things I learned:


The device works as a alarm clock, but instead of making a sound at a determined time, it gradually increases the brightness of a lamp.

The interface consists of a button and a rotary input. Rotating the knob adjusts the light brightness, but it can switch to to adjusting other values by pressing the button. The other settings are:

When the alarm on time is reach, the lamp gradually turns on during the next 16 minutes following an exponential curve from PWM level 1 to 65535. This approximately doubles the brightness every minute.


The LED is a high CRI LED from Yujileds. It is specified with a correlated color temperature of 5600K ±300 and CRI of 95±1. I measured its spectrum and got CIE 1931 xy:


This is a correlated color temperature of 5762K. The CRI is 95.13. Here is a graph of the measure spectrum from 380nm to 745nm.

The light spectrom of the LED in the lamp. A line starting at zero for 380nm, a sharp peak at 446nm and a falling off to about half of the peak for longer wavelengths.


  1. YJ-BC-2835L-G02, Yujileds. https://www.yujiintl.com/upload/file/2020/20200303/20200303182322_58721.pdf
  2. Electrokit, a web shop selling electronic components. https://www.electrokit.com

©2022 Mats Mattsson