I have three independent ‘dawn to dusk’ circuits, the newest about 15 years old. All use the basic LDR voltage divider design with Schmitt, logic, relay, etc. Triggering mains lights around the house and garden. But over three decades or so I must have replaced the LDRs dozens of times. Sooner or later they all deteriorate to the point when their resistance range falls significantly.
So I’m considering replacing all three with a single UNO circuit. Its output High or Low would go to the existing logic and relay driving circuitry.
I’d prefer to achieve this without adding an RTC or other hardware and without using specialist libraries. (Those I’ve studied briefly look dauntingly complicated.) Accuracy is of no importance. But I would like to be able to easily adjust its daily On and Off times, seasonally for instance. At least by removing it from its eventual dedicated 328 socket to recompile the sketch on the PC. Ideally it would be great do so in-situ, say by using a couple of buttons to add or subtract an hour from On or Off times, but maybe that would be pushing it!
A quicker solution for me, as an experienced hobbyist, would almost certainly be to stay with legacy electronics and redesign a single circuit using a much more reliable sensor. Perhaps a photodiode? Or even buy a small digital timer and design an add-on to rectify the audio. But I’m on the low slopes of the Arduino learning curve and this is an opportunity to advance a bit.
All advice and practical recommendations would be much appreciated please. And particularly any that point me to existing code to get me started. I have written a few simple millis()-based sketches but still regard myself as a novice.