Have your already set up a Christmas tree in your house and decorated it with traditional lights? Build a couple of these led lights to enhance the Christmas mood. The coloured LEDs blink in a seemingly random sequence and rate and create a festive appearance that is perfect for these special holiday.
The led Christmas lights circuit has a very simple design. It is based on a type 4060 digital counter(IC1). This IC has a built-in oscillator with a frequency set by the combination of resistor R1 and capacitor C1. The oscillator frequency is approximately 5 kHz with the component values shown here. The oscillator signal is divided by various factors by the internal digital circuitry of the IC.
The division factors are designated by ‘CT’ in the IC drawing symbol. For instance, the signal on the CT3 output (pin 7) is a square wave with a frequency equal to 5 kHz divided by 23, which mean (5 kHz : 8) = 625 Hz.
The oscillator signal is divided by 24 (16) on the CT4 output, by 25 (32) on the CT5 output, and so on. The signals on each of the outputs thus change at different rates. Eleven LEDs are connected in three groups between six of the counter outputs, with the result that the group of LEDs flash in an apparently random pattern.
To assemble the led Christmas lights circuit, first solder the IC socket (mind the polarity), the two resistors, the capacitor, and the battery clip to the triangular circuit board. Then fit the eleven LEDs. Pay attention to the polarity of the leads: the short lead is the cathode lead. After a final inspection, you can connect a 9-V battery to your Christmas LED decoration>. It should produce a festive blinking pattern!