Ambient Light Sensor for Mosaic

do you need to adjust depending on daylight intensity? or is it just turning something on /off based on a threshold? 

Just to trigger something based on a threshold

If that's the case - most commercially available photo sensors have a contact closure on them that you can hook up to the contact input of the mosaic to trigger an event.   

Here's a modular unit tat lets you adjust the sensitivity onboard : https://protosupplies.com/product/photodiode-light-sensitive-relay-module-5v/ 

most installation sensors will wrk too if they have low voltage relays: https://www.acuitybrands.com/products/detail/107199/sensorswitch/cm-adc/dimming-photocell-ceiling-low-volt

Home depot has some for landscape lights that will work as well

If that's the case - most commercially available photo sensors have a contact closure on them that you can hook up to the contact input of the mosaic to trigger an event.   

Here's a modular unit tat lets you adjust the sensitivity onboard : https://protosupplies.com/product/photodiode-light-sensitive-relay-module-5v/ 

most installation sensors will wrk too if they have low voltage relays: https://www.acuitybrands.com/products/detail/107199/sensorswitch/cm-adc/dimming-photocell-ceiling-low-volt

Home depot has some for landscape lights that will work as well