Detect LED

[crazynight]

Looking to detect if an LED is illuminated or not, will server several purposes from the boiler to the alarm system, neither are smart as yet so want to just log are they on or not so I can start building patterns with relation to the house heat ready for when we upgrade to smart devices.

I know a photoresistor should work but just can't get it sorted out any suggestions or alternatives welcome.

[grovkillen]

If you use one of these modules you can use the potentiometer to adjust the level of light that will trigger the digital pin. Then you can use it as a switch input.

http://s.click.aliexpress.com/e/zD5hcIk