A USB port is a great power source for charging a single cell Lithium-Ion battery. It is capable of supplying a maximum of 5.25V and 500 mA. The circuit above is a USB powered single cell Li-Ion battery charger. LM3622 is used as the controller. This special purpose IC has a precise end-of-charge control and low battery leakage current about 200nA. S1 and S2 select the low voltage detect enable/disable. The low voltage detection is handy for conditioning a deeply discharged battery with a low current stage, to prepare it for the full charge cycle.
LM3622 Li-Ion USB Battery Charger - [Link]
BreadBoardManiac have been making some cool prototyping boards and accessories like their thin, double-sided, BiscuitBoard and CakeBoard that can be physically mounted onto the LEGO brick system, they even produce a special breadboard made of wood! Along with the accessories is a wire stripping gauge that allows you to accurately bend wire interconnects and cut them to the correct length so that they all line up neat and tidy, flush with the surface of the solderless prototyping board. The finished wiring looks like a work of modern art rather than the messy rats nest effect that you normally get with flying leads. You have probably already worked out that these people are passionate about breadboarding.
Neat Breadboard Connector - [Link]
Brian Dorey made this DIY USB to RS485 adapter, that is available at Github:
We looked for a full-duplex ready-made adapter but all the ones we found are only half duplex devices and as we needed to be able to supply 12 volts via the RJ45 connectors on the slave boards we decided to make our own USB to RS485 full duplex adapter using a USB converter chip from FTDI.
The board uses an FT230X with an RS485 converter chip which outputs to a set of header pins and also an RJ45 socket.
The new adapter board can supply power to the slave devices through the USB port or can be powered from an external supply by removing a power selector jumper. The board also has an on board 120R terminator resistor with selection jumper and LED’s to show serial activity.
USB to RS485 adapter - [Link]
Alan Parekh @ hackedgadgets.com writes:
This video was going to be a repair of this Portable USB Charger but as it turns out there wasn’t anything electrically wrong with it. It didn’t work out of the box but I think that must have been caused by some oxidation on the USB contacts. It seems to work like a champ now. The control chip for the DC/DC converter looks to be this DHMF chip. I have never seen the swoop logo before and can’t seem to find any data on this 5 pin device though. It is probably similar to the LT1302 (PDF) that the Adafruit MintyBoost uses. The efficiency of this circuit doesn’t appear to be as efficient as a proper one built using the LT1302 though since when drawing 500mA from the output it can maintain very close to 5 volts out (2.5 watts) but needs an input of 3 volt at 1.3 amps to do it (3.9 watts). This gives us an efficiency of about 64%, the graph from the datasheet of the LT1302 indicates that it could perform at about 86% under these conditions.
Portable USB Charger Teardown - [Link]
One basic need of a computer scientist is to measure the power that a USB device drains off the PC. This device is plugged between the PC and a USB device and displays the current on an LCD. For currents under 100mA it is displayd in 0.5mA steps and 1mA steps for currents over 99.5mA. It is built with an AVR programmed in assembler.
USB Power Monitor - [Link]
This project started out from a need to build a simple device for monitoring the CAN bus. I choose the NUC140LC1CN 32K Cortex-M0 microprocessor from Nuvoton for major reason – it has both USB and CAN peripherals.
CAN to USB Interface - [Link]
IViny is easy to use and USB based simple low-cost DAQ and measurement device for data acquisition application. It can be used quickly without any low level electronically knowledge.
- 2 channels 0 – 5V and 0 – 3V digital input/output
- 2 channels 0 – 5V 10 bit analog input
- Channel maximum current 20 mA
- ATTiny85 based
- USB supply, no need external supply
- V-USB based communication
- PC user interface
- 150 S/s (it will increase with future next firmware upgrade still under development)
- 50 mm x 33 mm x 17 mm
IViny Compact Data Acquisition Device - [Link]
Charge and protect your devices while blocking data syncing and “juice jacking.” For work, home, travel, everywhere!
If you charge via USB – which all smartphones and tablets do – Umbrella will protect your data. When connected to any USB port, Umbrella allows power to flow to your device so it can charge, but physically disconnects the data connections – eliminating any possible data theft or leak.
Umbrella USB - [Link]
This USB to serial converter project is easy to build, it is simple and inexpensive. It is based on the FT230XS from FTDI Chip.
USB to Serial converter using FTDI FT230X - [Link]