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I have been to an event last night, where I some wristbands produced by the Crowdled company (see links at the end).

Material of one band: 3 colored leds (2 in total) and a button. Runs on battery. For the pictures I opened the bands (2 screws). In the middle of the IC the code FL27.138 ist labeled. The rest of the band which is not visible in the pictures is only plastic. pic1 pic2

Functionality: once I reveived the band, the button changed color and turned the leds on an off. Later a radio controller controlled the leds, the button couldn't even turn the leds off. (Range: about 750 metres, regarding the website of the producer). One day later, at home, the bands do not turn on at all, even those which haven't been activated at the event (plastic seal at battery was attached). EDIT: The bands work like when I received them. The problem was empty batteries.

Question (EDIT): How can I reuse the bands? Probably the radio contoller consumes energy for the whole time, which empties the battery's within a day. Any idea how to disable the controller?

Links and further information: producer: https://www.crowdled.net/how-does-it-work/ similar hacks for other bands: http://www.instructables.com/id/Hack-Your-Xyloband/ and https://www.youtube.com/watch?v=UQHpJ0dJJXQ

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  • \$\begingroup\$ Step one is to figure out what parts are being used. Step two is to draw out a schematic. \$\endgroup\$ – Ignacio Vazquez-Abrams Jun 3 '18 at 23:32
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    \$\begingroup\$ Who voted this as a repair question? Stop abusing the close vote system. \$\endgroup\$ – Passerby Jun 3 '18 at 23:42
  • \$\begingroup\$ first step is get the FCC id. Then get the fcc documents. This gives a ton of info. \$\endgroup\$ – Passerby Jun 3 '18 at 23:43
  • \$\begingroup\$ Or your countries equivalent. The second would be a receiver to scan for codes being transmitted but that's unlikely in your situation. \$\endgroup\$ – Passerby Jun 3 '18 at 23:50
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    \$\begingroup\$ @Passerby - the question has the same issue of lack of design documentation as a repair question. And the goal was to restore some sort of functionality. Rather obviously it is off topic, though probably more as a use of consumer products than as repair. It is also "too board" since there is no specific goal - ie, the same problem as the classic "what project can I do" or "what can I do with a soldering iron" questions. \$\endgroup\$ – Chris Stratton Jun 4 '18 at 16:59
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I've been trying to modify them too(older model). I have been trying to use a ESP8266 to change the leds so I can make an app for it, however, it didn't work out. This is what I've researched until now: the two IC's is a LED driver and a receiver. The number on the driver doesn't seem to "exist" when you try to search it up. The receiver, however, is a CMT2210LCW.

Somehow, I've managed to switch between modes by mounting a button connecting the GND to one of the pins which I don't remember on the rgb led driver. Measure the pins and lines before trying this out.

The radiocontroller has a data output pin which outputs a demodulated signal. If you're not using it, I suggest you to drive pin 4(SDN) high to disable the receiver. Don't scratch the supply line off yet, since it might come in handy after some more developing. Try to see if the wristband survives longer than a day.

Oh, one more note, I've been doing this on a older model which has a number on the receiver. I don't know for sure if it's the same IC, or if it has the same lay-out.

P.S. I modified the wristband with a concealed button to switch between lighting modes. Sadly, no control via radiowaves yet.

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  • \$\begingroup\$ You were trying to control the bracelet built around a CMT2210LCW (315/433.92 MHz RF), from a ESP8266 board (wifi 2.4GHz)? I'm not surprised it didn't work out. \$\endgroup\$ – dim Jun 5 '18 at 12:46
  • \$\begingroup\$ Sorry if I am unclear, but I wanted to control the driver with the esp (wemos d1 mini) with the I/O. I had a little bigger wristband to build it in. Instead of doing that, I just made a hidden button to change mode. I am only able to change modes, not control the driver itself since I can't find any datasheet or information on that particular IC. \$\endgroup\$ – Capt. Frost Jun 6 '18 at 7:11

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