I'm looking into designing a badge for a tech conference and we're thinking of creating a small PCB with one or more LEDs on it.
- Less than $5 per unit for 2500 badges
- The PCB has to be around the size of a 3.5" floppy with place to add a sticker with the participant's name of it
- A silk layer would be nice to show of the parts and complete the "geek" feeling
- Ideally it would run on a "button"/"cell" battery, but a AAA battery might be needed.
- It would be nice if it would run for up to a year, but the conference is two days so anything that would run for at least three days is doable
Options we're thinking of:
- Blinking a single red LED
- One "glowing" RGB led that changes between the three different colors of the event's design
- A strip of RGB LEDs making the whole badge "glow"
- Using some kind of plastic to use less LEDs to illuminate more of the badge
The question is: what kind of architectures should I look into?
The LM3909 is supposed to be nice, but out of production. Are there any replacement components like that?
For stuff that glows I see two possibilities some MCU (MSP430 perhaps?) to do PWM between one or three colors or use a D/A to set the voltage of the LED to an appropriate level.