Friday, October 12, 2012

Cheap LED Christmas Lights

I need to mention a smokin' deal I found today. 100 multi-color LED lights, with 8 programs, for only p169.50 (about $4). We have been seeing lights like these on sale for p600 (about $15) - but NEVER this low. I bought 4 strings today - we are buying 6 more tomorrow. Good quality, strong, reasonably bright. Interestingly, there is NO indication where they are made. My guess is China.

I have dissected one string of lights and found out a few interesting things:
  • Although there are 4 colors, there's only two control lines. So all of the blues and greens are on one control, and the yellows and reds are on the other.
  • Having only two control lines (instead of 4) reduces the amount of wire needed (by about 1/3).
  • Having only two controls lines eliminates two transistors that would be needed for control.
  • Fewer control lines also means a simpler microcontroller with only 2 output pins instead of 4.
So - simpler micro, 1/2 the number of transistors and 1/3 the amount of wire translates to the lower cost. The more expensive strings have 4 control lines (I have dissected one of those last year).

The nice thing is - for $4, I can get 25 each of red, blue, green and yellow LEDs. Plus lots of wire. Plus AC plugs and sockets. And a couple of control transistors, a pushbutton switch, and a couple other misc. components. A tinkerer's dream.


  1. where have you bought this?

  2. At the UNO store on the third floor of the Pure Gold building in Taguig City, Philippines. Unfortunately, I think they are all sold out now.