Week 12: March 27th - April 2nd

Individual Log - Zach

I started my week by completing the assembly of the AC-DC converter and AC pass-through, since I discovered last week I had purchased the wrong wiring. The new wiring is 14 AWG THHN wire, commonly used in household electrical circuits and is rated for 120VAC circuits.

A burn-in and load test was performed on the AC-DC converter later in the week with thermal imaging to monitor the temperature of the converter at different loads. The burn-in consisted of a one hour run at 90% load (0.3A) in which thermal pictures were taken at time marks of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, and 60 minutes. At 90% load the converter reached a maximum of 50 Celsius within 5 minutes before settling at 41 Celsius for the remainder of the test. The converter was given 10 minutes to cool down before subsequent testing was performed.

90% Load Test -- 60 Minutes

Subsequent testing involved load testing at the expected maximum current draw of the thermostat (~40mA) for 30 minutes (maximum estimated length of system use at any one time), and in intervals of 5 minutes each alternating between 30mA and 10mA. In each test, the temperature of the converter reached a maximum of 31 Celsius with a minimum of 28 Celsius.

12% Load Test -- 30 Minutes

A table showing the results, as well as a FLIR thermal report will be created and put into the report for preliminary work before submission next week.

A mock up of thermostat circuit topology was built on a breadboard, however some components were missing and the breadboard circuit is yet to be complete. These remaining parts arrived Wednesday evening and will be apart of the coming weeks logs.

The remainder of the week was spent writing more sections of the report, proof-reading sections for editing, and adding photos, tables, and aligning references with their appropriate entries in the report.

To conclude the week, some work was performed to test the validity of LCD backlight control with a transistor, and to understand the best method for implementation. There are still some questions I'm working through to ensure the current provided is adequate enough to supply the backlight using the transistor setup. Alternatively, further research this week revealed that this may be possible using only the Arduino itself so long as the LCD chosen has a specific configuration (old models vs. newer editions).