Control with a relay card

Control with a relay card: card

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Often we see and read about technical stuff that someone has built again and thus his coffee machine via mobile phone turns on. Enthusiastic but certainly a little envious, we then consider how and what we could implement for ourselves. Half an hour later we get up, go to the kitchen and once again make coffee alone. And why are we doing this? Apart from the fact that we have coffee thirst - because we think that we can not build such things anyway anyway. This very idea is wrong.

Everyone can control something with relay cards

Let's start from the beginning. Why did I come to this? I am a reptile owner - especially bearded dragons. Now these animals like to hibernate and also have to somehow know when it actually is winter. This is regulated by the lighting. There are long days in summer and short in winter. So the body adjusts itself (with us not differently) on the appropriate season. In order to simulate this in the terrarium, the timers have to be reprogrammed 1-2 times per month, thus lengthening or shortening the lighting time. Yes, that is annoying and somehow my neon lamps have always reset the settings of my digital timers when starting. It has to be easier and better with a computer. It goes and I never turn a timer again.

The required hardware

Control with a relay card: computer

Relay card as a kit

To control something with a relay card, of course you need one first. Since the selection is large and the prices range from 12 € to... (far above my craft limit). There are differences in the connection.

  • parallel interface (e.g., printer port) - Simple, inexpensive, sufficient for many applications but with a disadvantage. When the computer is started, a signal is sent to the parallel port and a relay card turns on all outputs. If you switch on the relay card or if the computer runs permanently, this is not a problem.
  • serial interface (Eg 9pol D-Sub) - A little more expensive, but without interference when starting the computer. Disadvantage, the serial port is often used elsewhere.
  • USB port - Sure the easiest way, but a bit more expensive and often here special software is needed to match the relay card.

In addition, of course, you need a control unit. The easiest way is the most common computer. But also possible are more economical variants, such as Arduino or radio receiver modules. But we do not dare to venture into this topic so deeply. I finally claim that anyone can. Therefore we start from the simplest variant - an existing computer and a parallel relay card incl. software.

Last week, I treated myself to a relay card. 12 € for a kit promise crafting fun and then certainly some "useful" use. Well, the fun is easy to pull on 2-3 hours and for some the fun ends after the first. Who wants to do without, gives about twice and buys a finished model. You usually get a required connection cable, buy it extra or adapt an existing one.

Control with a relay card: control

Relay card ready set up

The required software

Here are the differences big and there are free software, really good for some money and who can, write yourself. My software falls into the category "some money, but really good". Once € 60 and all my applications are covered. But the included software does not have to hide. Basic functions such as manual switching, random switching and timer bring almost all with. My software can do a little more, but I write something in my use cases.

Function and structure

The function is quite simple. The computer outputs small signals at the output, the relay card amplifies them, forwards them to relays, and allows large loads, such as roller shutter motors or lamps, to be switched on. However, if you have no experience and knowledge in the 230V range, you should stop at the relay card and get a specialist to do so. Whether the card and the controller works, you can usually see on LED's, which indicate the switching state of the relay card.
The structure is as simple as the function. Connect the connection cable between the computer and the relay card, supply the relay card with power via a plug-in power supply unit, install and start the software. Already the relay card is ready for use. I think, now you believe me - anyone can do that.

Why can you use a relay card?

As a basic statement: to just about everything. The question is rather, what do I want to implement. Because the real work starts behind the map. The card operates only relays, which are simple on-off switch or switch. What you realize with it depends on your imagination and ability. I have not learned anything in this area, but have been busy with circuits since school and have my experience. By my examples I would like to show what is possible.

Party lighting

My relay card built at the weekend I used for demonstration purposes as party lighting. For this, however, the appropriate software is necessary (in my incl.). This converts music, which runs on the computer, into switching signals and sends them to the ralais card. My example is somewhat slimmed down, since the relay card has eight outputs, but I had only five LED Stripe. But I think the function is clearly demonstrated.

The music certainly does not meet all tastes ? Only, as far as the copyright is concerned, one should be careful and so I have opted for a video of my uncle. Copyright is thus clarified.

Lighting control in the terrarium

As described earlier, my animals need different lighting times. My relay card is used in this case as a "simple" timer. "Simple", because the lighting times are daily according to the current sunrise and sunset times. The software calculates according to the entered coordinates, the exact times for my place of residence. When the sun comes up, the light goes on in the terrarium too. In summer this is earlier and in winter just later. So also my animals have long and short days and they register the seasons. Those who are interested in that is called Astro-times and there are also finished timers that take these times into account.

Shutter control

Control with a relay card: control

With a little more effort, even such projects can be implemented. Later it will certainly be complicated, but since I have already planned this control in the house, I have also laid the appropriate cable. Exactly this means that each window has got an extra power cable (5 × 1.5) to the fuse box and there is an additional switch box with several relays.

The astronomical time function is used again. In the morning I let the shutters open at a certain time (who wants to be awakened by the sunrise on the WE) and in the evening they close when the sun goes down. Never run around the house and open or close 13 shutters. Whether summer or winter, the shutters close when the sun goes to sleep. A luxury that almost anyone can implement themselves. If I roughly rollover, the structure including additional cable and relay cost me 150 €. Plus a few hours I sat in front of the switchboard at night. Why, you can see for sure in the picture.

As a small treat, there are apps that can take over the control of a computer. If I lie somewhere in the sun and have forgotten to close the shutters as a sunscreen, I can do that manually with the phone. Not even something has to be built for this handset control. I use the computer remotely and can thus also access the software of the relay card.

Control with a relay card: control

With a mouse click the desk opens and the balcony door can be used

Desk with lift function

My desk is in the hallway, right in front of the balcony door. Of course, sometimes I want to go to the balcony and that's why I have to walk through the desk. Of course you could also manually operate and secure the folding worktop, but with me take over the two Hubmotoren, which are controlled by a relay card. So that in this case the desk does not just open or close when I start the computer, I could not use a parallel relay card and reached for a USB port. Costs amount to about 20 € for a card with 4 relays.

Now I hope that maybe one or the other will find taste and maybe even dares to do that. I would be happy to present your results.

Video Board: Learning Relay Board & Connection With PLC Output