First LOGO! Project: Yard Light on a Dusk Sensor and a Clock
A classic first project for beginners: a twilight sensor turns the yard light on, and a weekly clock switches it off around 23:00 and stops it from staying on after 6:00 in daylight. Here are the blocks, the logic and the order to build and test it in, before anything gets connected in the panel.
How to build this project
Connect the twilight sensor to an input
A light sensor sends a signal when it gets dark outside — this is the first input block in the logic.
Set up the weekly clock
The clock block sets the window when the light is allowed to be on, for example from dusk until 23:00 and from 6:00 until sunrise.
Combine with AND/OR logic
An AND block lets the light run only when it's both dark and inside the clock's window — add an OR block if you also want a manual switch.
Test in the simulator, then connect
Try both scenarios in the LOGO! Soft Comfort simulator, and only then let an electrician connect the 230V side.
Why this is a good first attempt
blocks, one clear result
Twilight input, weekly clock and AND/OR logic — simple enough for a beginner, yet it shows the whole basic principle.
Twilight sensor input
A light sensor is the first input signal — it decides whether it's dark enough outside for the light to be allowed on.
Weekly clock block
The clock limits when the light can be on, for example until 23:00 at night and from 6:00 in the morning — it stops the light staying on all night.
AND/OR logic combination
An AND block combines both conditions — dark AND within the clock's window — before the output signal; OR adds a manual option.
Testing in the simulator
Before touching any wiring, you can simulate day and night scenarios in LOGO! Soft Comfort.
The 230V side is for an electrician
You can build the logic and program yourself; leave connecting the output relay to the 230V lighting circuit to a certified electrician.
What you learn from this project
Fundamentals you'll reuse in any other LOGO! project afterwards.
- Block diagram: twilight sensor + clock + AND/OR logic
- A suggested time window and how to change it
- Steps for simulation in LOGO! Soft Comfort
- The safety line — where your part ends
- Ideas for what to try after this first project
Frequently asked questions
Why use a clock if there's already a twilight sensor?
Without a clock, the light would stay on all night while it's dark outside — the clock switches it off around 23:00, saving energy and not bothering neighbours.
Can I change the time the light switches off?
Yes — the weekly clock block in LOGO! Soft Comfort can be reprogrammed at any time, including separately for each day of the week.
Can this same logic be used with a different sensor?
Yes — the same AND/OR structure also works for a motion sensor, a temperature switch, or any other input signal that needs a time limit.
Why test in the simulator instead of on site right away?
The simulator shows logic mistakes before they become a real problem with power connected — it's much safer and faster to fix the diagram on a computer.
What if the light doesn't turn on after installation?
First check in the simulator that the logic runs correctly; if it does, the issue is usually in the sensor wiring or relay connections, which an electrician can check.
Ready to build your own yard light?
Browse twilight sensors and LOGO! modules in the shop and start with this first project.