Planet Arduino

Surely you need yet another way to charge your lithium batteries—perhaps you can sate your desperation with this programmable multi (or single) cell lithium charger shield for the Arduino?! Okay, so you’re not hurting for another method of juicing up your batteries. If you’re a regular around these parts of the interwebs, you’ll recall the lithium charging guide and that rather incredible, near-encyclopedic rundown of both batteries and chargers, which likely kept your charging needs under control.

That said, this shield by Electro-Labs might be the perfect transition for the die-hard-’duino fanatic looking to migrate to tougher projects. The build features an LCD and four-button interface to fiddle with settings, and is based around an LT1510 constant current/constant voltage charger IC. You can find the schematic, bill of materials, code, and PCB design on the Electro-Labs webpage, as well as a brief rundown explaining how the circuit works. Still want to add on the design? Throw in one of these Li-ion holders for quick battery swapping action.

[via Embedded Lab]

Mike Buss used an Arduino Duemilanove, Parallax RFID reader, micro servo, and piezo electric speaker to make a personalized, lockable keepsake box for his girlfriend’s birthday:

The outside of the box is really simple: it just contains a button and an RGB LED. When she presses the button, the LED lights up green or red depending on if the box is locked. When she waves one of the three personalized RFID cards over the box, a little tune plays and the box unlocks.

As part of the project I also did some cool trick with a Pololu pushbutton power switch to make the battery last a lot longer. Since the Arduino is only powered for a few seconds when listening for RFID tags, the battery lasts a lot longer. When the box is finished locking or unlocking (or after a small time delay), it sends a signal to the power switch to turn off the power and conserve battery life. The box has been running on the same 9V battery I put in 4 years ago!