Diy Christmas lights

Introduction

Make a simple battery powered Christmas light with seven (7) leds.

Theory

Use leds in series, as parallel leds might light on uneven brightness.

LEDs and wiring

• Red and yellow led: 2 V
• Green and blue led: 2.9 V
• White: 3.3 V

Seven blue leds makes $7\times 2.9V=20.3V$, and white blue leds drops the voltage by $7\times 3.3V=23.1V$. If we use simple AA batteries, we will need $14\times 1.5=21V$ or $16\times 1.5=24V$. Quite many. . .

However, if we wire them alternately, it makes $3\times 2.9V=8.7V$ and $4\times 2.9V=11.6V$ for blue led and $3\times 3.3V=9,9V$ and $4\times 3.3V=13,2V$ the white leds.