Chandelier control by two wires

Now in almost any lighting store (and not only) you can buy a chandelier that is controlled by a remote control, allows you to adjust the brightness and warmth of the lighting, etc. But is it sports? All I need is to turn on either two light bulbs on the chandelier, or five.

How to downsize?

The first thing that came to mind was to use two relays instead of three (these are classic circuits, which are full on the Internet). On three relays, I did it only because of the absence at that moment of a relay with two groups of contacts. It was decided to replace it with IM03TS. These are rather miniature relays with a minimum of 2A switching, which is enough for me.

The second is, of course, a step-down transformer. He has everything big: weight, dimensions and cost. Since I placed my first version behind a stretch ceiling and there was plenty of space, I didn’t really care. I want to place this design in a chandelier, so it has become critical. At the first moment, it was decided to replace the power circuit with a simple AC-DC LNK306PN. The circuit I have already debugged in another device, gives > 200mA, in general, what you need. Of course, you can just take a charger from your phone, But not all yogurts are created equal. But the quality, as you know, is not the same for everyone.

By the way, there are different control schemes – this is on a thermistor, on diodes, thyristors and many others. Also, about control methods – these are Wi-Fi, IR, 433 MHz, “on cotton”, etc. I liked the relay circuit. Simple and reliable.

Fig.1.  Diagram AC-DC LNK306PN
Fig.1. Diagram AC-DC LNK306PN

The dimensions turned out to be excellent, but still, I decided to convert the power supply to a circuit with a quenching capacitor. I measured the current of the relay winding, it turned out 20mA. I looked at the calculations of the capacitor in the online calculator, everything seems to be fine. At first I thought to leave only a capacitor with a resistor, a bridge and a zener diode, but at the very last moment I added a 5V LDO – it would be more reliable.

Fig.2.  Device diagram
Fig.2. Device diagram

Circuit operation

According to the calculations, the capacitor turned out to be 1-1.5uF. I set the zener diode to 5.1V. LDO any 5V in SOT223. When you turn it on for the first time, power from the 220V network is supplied to the X3 connector and, accordingly, the first group of bulbs on the chandelier lit up. Also, the mains power comes to the rectifier and step-down circuit. 5V through the normally closed contacts of relay K1 is fed to the coil of relay K2 (K1_REL), which operates and charges the capacitors C6-C8. It depends on the total capacitance of the capacitors for how long it is necessary to turn off and turn on the light in order for both groups of bulbs on the chandelier to light up. After a short power failure, relay K1 turns off the power to relay K2 and the voltage from the capacitors appears on the coil of relay K1, switching the second group of contacts and lighting the second group of bulbs on the chandelier. Phew, didn’t seem to mix anything up. In my case, three 470uF capacitors give about one second to turn on again.

Fig.3.  Switch board
Fig.3. Switch board

The pay is pretty simple. I made more gaps for 220V conductors. In principle, all components can be output.

Fig.4.  Assembled device
Fig.4. Assembled device

The condenser in the bins found only a “horse” size. They are smaller (15mm high) K73-17 for 400V, when I test it thoroughly, I will change it. I found a 40mm heat shrink tube, it will be possible to insert and shrink.


I follow the news on Habré and see fewer and fewer articles related to the development of electronics. Write articles, post your projects, share your skills – everyone is interested! All the best!

Thank you for your attention!

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