microcontroller in X-mas lights?

Thread Starter


Joined Nov 4, 2007
well, friends,yesterday i saw a X-mas light opened it had a capacitor,four diodes and a circuit having 8 pins,it looked like a drop of ink on the circuit.

my question is, could it be a microcontroller?
does a microntroller looks like a chip just as the microprocessor in the pc,if no then what it could possibly be controlling the lights?

plz reply
with regards


Joined Aug 15, 2007
my question is, could it be a microcontroller?
Yep. It could be. If the thing is rounded -- as it sounds from your description -- it may have been "potted": black gloop is dripped over the circuit (or part of it) in order to prevent the competition from accessing it and reverse-engineering it. (Who'da thunk Santa was in such a cut-throat business?)

Micros are getting smaller and smaller. There used to be an emulator here at work that was called "the suitcase" for the obvious reason. I just got an MSP430 development kit from TI that is about the size of my thumb! The entire kit!



Joined Jul 22, 2007
The 'black spot' is called a COB (circuit-on-board). Saves time and money manufacturing. The actual chip of silicon in an IC is really tiny. Probably is an MCU, they could use the same board and program many different patterns and effects.


Joined Jun 30, 2006
+1 HarveyH42, it could be to prevent reverse engineering but it's usually just the die of an ic stuck on the board and machine wired then goo put over it. Of the ones I've cut the goo off of the smallest die was about 1mm.
With the arduino http://www.arduino.cc you want to do something like it

You can use a MAX7219.

Or you can use a HEF4794B, in which I individually control 16 LEDs with two of the ICs. This can be modified to control multiple LEDs at once.

There is also the 74HC595