Dark On, Reset, Wait Until Next Dark On

Thread Starter


Joined Apr 20, 2016

I am in need of a basic circuit to turn on a LED or relay at dark, then when reset wait until the next dark (next evening) to turn on again. The reset could happen soon, or several hours after first dark trigger, but once reset, not on again until preferably the next evening.

Anything out there?

Thanks in advance for any help!



Joined Nov 30, 2010
Here's one I did 30 years ago. It's very complex compared to most do-it-yourself circuits, but it's a good thing to learn from.
It is also very god at what it does, with latch outs for both day and night and immunity to interference from passing cars.

ps, it's optimized for maximum battery life.

Edit: I just added a couple of labels to the drawing, 100k, 39k, and the low current diodes.
The NPN transistors are anything you have in a TO-92 or smaller. You can't buy a transistor that isn't good enough for this job.
Last edited: