Arduino SMS device

Submitted by wade on Tue, 2013-12-31 02:25

I'm working on an SMS device that is programmed in the Arduino IDE and uses a tiny chorded keyboard for input, a SIM900 GSM module to accept standard AT commands, and a Nokia5110 LCD to display output. I stopped by earlier this evening and Paul (thanks Paul!) helped me debug. I've posted a thread on the forum but basically I'm having trouble getting my sketch to run in the tiny 2K of RAM available on the ATmega328.

USB charging port for an ebike

Submitted by Scott Baker on Fri, 2013-12-20 13:53

I ride an electric bicycle that uses a 48V battery for it's energy source and there have been times when it would have been convenient to have a USB charging port (for charging my phone or any other other device that can recharge from a USB port).  So I built this USB charging port (basically a DC-to-DC converter capable of handling up to 60V input voltage).  I used the OSH Park circuit board prototyping service which worked perfectly.  I wrote an instructable about the build here:

Battery Pack Load

Submitted by paul on Tue, 2013-11-05 12:45

I purchased a cheap USB power pack, thinking it would be ideal for powering small projects.  But it automatically shuts off if the device isn't drawing a lot of power, since it's meant for charging cell phones.

Here's a 2 transistor circuit I built this morning that keeps it on with very little battery drain by using brief pulses.

Click "Read more" for the schematic, design details, and a PCB.....