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  • Author Author: dubbie
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Bluetooth Controller for LEDs #1 : De-constructing the Controller

dubbie

Whilst wandering around a local store after Christmas looking for reduced cost Christmas decorations and hence bargains - of which there were only a very small number this year, I noticed a Christmas Wonderland Bluetooth Transfer, for controlling a string of LEDs. Normally I would have just ignored this as left-over controllers are usually useless as all the things they might control have been sold. But, as it mentioned Bluetooth I had a second look. There was almost a complete lack of information on the packing other than it seemed to be some sort of controller that had a Bluetooth link to your mobile phone. The modules themselves were only 50p which if they contained a useable Bluetooth module would be a complete bargain, so I bought one to dis-assemble.

 

The video below shows what I found inside which is a PCB with a transformer, reducing the voltage from mains to 36V ac (apparently) plus a Bluetooth module of some description, plus some other components, one of which is almost certainly some sort of microcontroller. Being a Chinese product it is probably one of their own controllers but I cannot be sure as I cannot read the markings on the chip.

 

 

This seemed so good that I went out and bought several more, plus a string of 500 LEDs to connect to the controller, which at £18.00 was not quite such a bargain. The wire from the controller to the LEDs is only two strands and the LEDs seem to be separated into two separate strings of 250 LEDs each. It seems reasonable to assume that half the 36V ac signal is being used to control one string of LEDs and the other half of the 36V ac signal is being used to control the other string of LEDs. By using pulse width modulation of the ac signals it would be possible to control the LEDS to be on, off flashing or slowly changing from on to off and vice versa. I'll get my oscilloscope out sometime and check this out.

 

I have not yet removed the Bluetooth module from the PCB yet as I thought I would try and work out what signals are being used, plus what power supplies it uses (I think it is 3.3V and 0V).

 

Obviously this should not be attempted by those who are uncertain of handling mains level voltage, which is most of us, or even all of us! as without the plastic casing there are exposed 240V connections and injury is highly possible. So, not to be attempted at home. I'll probably not try this myself, but just try to find the low voltage connections and use those.

 

Dubbie

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  • in reply to genebren

    Gene,

     

    Thanks for the encouragement. I did find it hard to believe that they were only 50p. They did have quite a few left so it might have been a poor seller and they just wanted to get rid of them. All the LED strings they fit already come with a manual controller so it is probably an extra that most people would not properly understand. The blurb on the packaging is not clear with regard to what they do. I was pleased because I had been looking at a WiFi controlled mains socket for £19.00 to do almost exactly the same thing, so even getting a Bluetooth version for 50p is great, and if I can work out how to use them on their own that will be even better.

     

    Dubbie