The Analog Plug is a small board containing the MCP3424 analog-to-digital converter with I2C bus interface. The ADC can take 4…240 samples per second, depending on resolution (12..18 bits). It has 4 differential input channels (just tie the “-” side to ground for single-ended use) and supports a voltage range from -2.048V to +2.048V, full scale.

An I2C bus running at 3.3V is used as interconnect, with all the power and signal lines brought out to to both sides of the board to allow daisy-chaining with other I2C-conformant boards.

The Analog Plug also makes a fine (3.3V) breakout board for the MCP3424 chip, if you wish to use it without a JeeNode. The only thing that is required is a translation of the header signals, DIO is SDA and AIO is SCL.

The pre-assembled version comes with the SMD-sized MCP3424 chip and decoupling capacitor already soldered onto the board. The Modern Device packing of this plug includes one right angle male header. This can be bent straight if right angle mounting is desired.

The PCB only variant contains just the board for the Analog Plug. No parts, no headers.

Resources
MCP3424 datasheet
JeeLabs Analog Plug Page