What Is an Astro Timer, or Another Useful Little Gadget.

I needed a lighting control timer for a project.
The lighting (a sign) had to switch on after dark. Usually, people just install a photocell switch for this, but it has its drawbacks.
I decided to tackle the problem with a special timer.

These specialized switches are also called astro timers.
An astro timer is essentially a regular timer, but one that tracks the sunrise and sunset cycles.
Since sunrise and sunset times vary with latitude, these timers let you set the latitude. The microcontroller has a table of sunrise and sunset times, which it uses to determine the times based on the day and month.

As I mentioned at the very beginning, the simplest use for this device is switching on lights at night. You can install a photocell switch, which usually costs less, but it has its drawbacks:
The photosensor has to be installed outdoors.
You have to keep an eye on the photosensor (if it gets dirty, the lights will stay on during the day).
If stray light hits the sensor, the lights won't come on when needed.
You can't set the lights to switch off automatically when they're not needed.
You can't switch the lights on earlier or later than the ambient light level would normally trigger them.

The astro timer avoids all these drawbacks.

At first, I was going to build a timer like this myself—or rather, not entirely by myself, but with help from a programmer friend. We'd already worked out the interface and I'd drawn up the circuit, but then I thought: wouldn't it be easier to just buy one? It turned out that alongside the branded devices, which are quite expensive, there are also Chinese ones you can find on AliExpress.
I ordered them, paid, and received them.

A few photos of the packaging. Nothing special: it was packed neatly. More details under the spoiler.

The package includes the timer itself and its manual. That's all, and really, there's nothing else you need.


The manual is in English and has lots of pictures.
But when I searched online, I could only find a brochure in English and a manual in Spanish. Just in case, I uploaded them to my Yandex Disk — link.
When I first started figuring out the settings, I spent a long time trying to understand the manual's instructions. The Spanish manual was a big help; I translated parts of it with Google Translate, and after that everything went smoothly.

The side has a diagram showing the terminal assignments and a quick guide to switching the output control modes.


More about the connections.
The timer contains a relay with one changeover contact set.
Power is supplied to terminals A1 and A2. The timer is designed to be connected to a 220–230 V mains supply, but it can easily be modified to run on 24 V (a version for this voltage is also available).
The diagrams show a jumper between terminals 3 and 4, but you should not install it—these terminals perform a full reset of the device (including the time and so on).
The output contacts should be self-explanatory.




There is a standard DIN rail mount on the bottom.


The timers look quite neat. I don't know whether this is an original or a clone of a better-known timer with the same name, made by the better-known company chint-electric, but I certainly have no complaints about the appearance.


The front panel has an LCD, an LED indicating the output status, and five control buttons.
From left to right:
MD — lock/unlock the device and select the mode.
R — turn the display on/off, reset a parameter, and act as a function key together with the MD button.
< — select the parameter to set
Down — decrease the selected parameter
Up — increase the selected parameter.


The display has quite a few different symbols, but not all of them are actually used. There is no day-of-the-week indicator, for example; I suspect this display is used in some other timers from the same manufacturer.


The timer is a standard two-module size for a DIN rail.
The manufacturer's drawing gives the dimensions in more detail.


In reality, the dimensions match the datasheet exactly.

I couldn't resist taking it apart, since there are only two cases when I don't disassemble electronics:
The device can't be taken apart, or there's a chance I won't be able to put it back together.
Someone stole my website password and I'm not the one writing the review :)

Next, I'll describe how to configure the device.
I really could have used these instructions when I first got the timers.
The manual includes a picture explaining the menu and descriptions of all the options. It all seems clear, but somehow it still isn't.


I'll also hide the setup instructions behind a spoiler.

You can also turn off the display if needed, to avoid being distracted by it or to reduce power consumption—I don't know, but the option is there.
Hold the R button to turn the display on or off. This works whether the keypad is locked or unlocked, and it doesn't affect the load switching either; it simply turns off the display.


So, in summary:
Pros.
Price
Functionality: 8 slots for setting load on/off times.
Doesn't heat up
Good build quality.
Easy to set up (as I found out later)

Cons.
Not enough power to switch on the relay when power is restored (more details in the review).

My opinion: A fairly well-made and convenient device for controlling a load based on sunrise and sunset times. I don't think I'll need all 8 setting slots, but having some spare can be useful. I was pleased with the build quality. The relay is nothing special, of course, but this type is quite common. It's a standard relay and can easily be replaced, or you can use an external contactor to switch a high-power load.

And that's the review.

Update: The seller has listed this item again.