Previously the prototype electronics for the load cells were connected and calibrated. The electronics were still in the prototype stage and in order to measure the thrust during the test, the display needs to be located remotely from the test stand. The electronics are now ready for testing and the remote display is working.

The first step was putting the electronics into two metal enclosures from RadioShack. The first enclosure was for the display and the second is to contain the Trinket Pro and the instrumentation amplifiers. The display requires 5V, Ground and two lines for the I2C interface with the Trinket Pro. To place the display remotely, each enclosure was fitted with a Cat 5 cable jack and a phone line was used to connect the two. Below is a picture of the display enclosure with the individual components. (enclosure, display, stand offs and Cat 5 jack)

The rest of the electronics in the second enclosure are shown below (Trinket Pro, Instrumentation Amps, Cat 5 Jack and load cells)

Here's everything pieced together with the covers off. A 9V battery was added with a switch to provide the power source.

The only issue was the length of the wire between the two enclosures. After connecting everything for the first time the display was not working. It was getting power and was grounded, so the likely culprit was that the power cord was too long for the I2C to work properly. A google search quickly turned up some suggestions on using pull up resistors between the power and the data lines to get the I2C interface to work. The easiest way to do this was to take two 1k resistors and insert them into the screw terminals on the display connectors (see below).

After that the display came right up.