[Fede.tft] wrote in to tell us about some work he’s been doing to save battery life for LED dominoes. He originally got the idea after reading this post about the electronic gaming pieces. That project was aimed at the 555 timer contest and therefore, used a 555 timer. [Fede.tft] calculates the battery life for the CR2302 battery in the 555 circuit at no more than about 80 days. That’s if you never use them and the LEDs are never illuminated. It makes sense to remove the batteries from the device when not in use, but a redesign to increase efficiency is definitely worth the effort.
This rendition does away with the 555 chip in favor of a CMOS chip. By building a circuit around four NAND gates of a CD4011 chip, the standby lifetime of the battery is calculated to increase to about 4.5 years. Not bad! Add to this the fact that replacing the 555 timer didn’t increase the component count, the price for the chip is similar to the 555, and you didn’t need to resort to a microcontroller. Yep, we like it.