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The Sun Dragon

The Sun Dragon

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The Sun Dragon
  • Odroid U3 compact single board computer
  • 1.7GHz Exynos4412 Prime Cortex-A9 Quad-core processor
  • 2 GB LPDDR2 RAM
  • 8 GB eMMC solid state drive (boot)
  • 200 GB micro SD solid state drive (data)
  • 3x USB 2.0 connections
  • LAN9730HSIC USB 2.0 to 10/100 Ethernet
  • U3 IO Shield expansion board
  • Custom voltage and current monitoring
  • 20-8 VDC to 5 VDC 15 watt power supply
  • 50 watt solar panel
  • 12 VDC, 18 Ah battery
  • 20 amp battery charger
The Sun Dragon

The Sun Dragon

(Click for larger image)

Background

The Sun Dragon is a solar powered web server. It consists of a single board computer, solar panel, sealed lead acid battery, and charger. During daylight hours, the solar panel power the single board computer and charges the battery. During the evening hours, the single board computer draws off the stored energy in the battery.

History

The Sun Dragon was commissioned during the summer of 2014 to with the purpose of becoming a solar powered web server to host DrQue.net. This came as part of an experiment with a Raspberry Pi to accomplish this task. However, the Raspberry Pi proved to be far too slow to take on this role and a search for a similar device with more computing power took place. The Odroid was by far the most powerful single-board computer in it's class while still having a small power draw.

An Odroid was purchased and testing began in August of 2014. The power draw was far better than anticipated, with the device and power supply idling around 1.6 watts. This kept the requirements for the solar power supply reasonable. However, problems with constructing the auxiliary circuitry led to the destruction of one Odroid, and the destruction of the Atmel chip on the I/O shield. This delayed the project for many months.

The Sun Dragon became fully self-monitoring on August 20, 2015. It had shown stability for running over 90 days without issue. On August 26, 2015 it took control of all web services of DrQue.net.

Ongoing issues

The self-monitoring functions of the Sun Dragon have been plagued with issues owing mainly to the fact I suck as an electrical engineer. I have destroyed numerous chips including several 16-bit ADC, precision op-amps, the Atmel CPU on the I/O shield (twice), and the power supply on the Odroid itself. I have learned a number of lessons in circuit design as a result but much of the Sun Dragon's early life has been without the ability to self-monitor.

The Sun Dragon

Sun Dragon, battery, charger and monitoring meters

(Click for larger image)

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