HOBO® 4-Channel External Logger

Brooke Clarke 2000 - 2007

This is a small battery powered data logger with 4 analog inputs each takes 0 to +2.5 volts.  It is powered by a CR2032 3 volt Lithium button battery.  The "Boxcar" software package is required to "launch" (set up the sampling rate, which channels are active, etc.) the Hobo and to read back it's data.
Radio Shack can order as RSU12045522 or get from Onset Computer Corporation - HOBO® 4-Channel External Logger -

Also see my Onset G-Pendant web page.


Using Readout on the 4-Channel unit stops the data logging.  The instructions are clear that launching the unit will clear the memory, but if reading the data stops the logging function that's the same as clearing the data because to get it going again you need to launch it!

The inputs have 2.5mm stereo audio jacks.

2.5mm Plug is Tech America 910-0727 in catalog but may not be on their web site

Internal Design

Chip Side of Board,     Battery Side of Board

Hobo to Computer Cable

The cable that comes with the Boxcar software package has a 3.5mm stereo audio plug ( Digikey CP-3502-ND, Tech America 910-0754) to connect to the Hobo and a DB9(f) that connects to the computer serial port (DB9(m).
CUI Stack carries both 2.5mm jacks and 3.5mm jacks -

TSL250 Light Sensor

By using the following parts I made up a light sensor:

Data Logged

Chan 1 Outside Temp RSU 12045530
Chan 2 Inside Light
Chan 3 Cloud Sensor
Chan 4 not used

Here is a file that was "exported" in Excel format for July (July5.txt)

Also see the G Pendant 3-axis Onset Data Logger

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