Richard Bailey proposes four options to light the 54 facets of Groovik's Cube for the Burning Man festival. Option 4, using RGB LEDs blended to create colors, is selected as the best option due to its flexibility, brightness, and low cost of $700 and 80 person hours. A digital switching current source circuit board is designed to power the LEDs efficiently without excess heat. Community members are trained and produce over 2000 parts in 80 person hours to build the cube lighting system.

1. Richard Bailey - Groovik’s Cube Production Lead - Electronics Goal: Light 54 Facets of the cube Brightly enough to be visible on playa Cheaply enough to be in budget Simply enough to be buildable and maintainable

2. Option 1: Use light bulbs and color gels 6 bulbs per 54 facets -> 324 bulbs lots of power and heat and heavy wires and relays Expensive generators and relays/switches for high power Lighting gels are expensive and fragile 6000 Watts -- $10,000 -- 700 person hours

3. Option 2: DMX LED light 1 DMX controlled light head per facet Expensive & low time investment Attempted to get corporate sponsorship/loan 1000 Watts -- $18,000

4. Option 3: Use 1 LED per color 6 LEDs per 54 facets -> 324 LEDs LED specific color for each face color Fixed color LEDs limited color animation options 1 LED at a time per facet Required 6 channel LED driver/PWM 200 Watts -- $1000

5. Option 4: Use RGB LED colors blended 6 LEDs per 54 facets -> 324 LEDs 2 Red – 2 Green – 2 Blue Blended colors – possible for all 3 on at once Twice as bright Software tunable colors late in development cycle Increased flexibility -> lower risk Requires only 3 channel LED driver/PWM 3400 Watts (all White) -- $700 -- driver needed Best option need solutions for PWM and Driver

6. LED driver requirement Maximize LED output while limiting current draw to prevent burnout. As temperature of LED increases the resistance drops causing an increase in current Driver is a current regulator or current source

7. LED driver off the shelf Low tech single channel (1 LED) Expensive ( $15 per channel / $45 per facet) Requires large resistor Requires many much hand soldering of many wires Or a custom circuit board Turns extra power into heat (Danger * 162) $2430 + 300 person hours

8. Linear current source controller Custom circuit board Many large expensive components Hand soldering of each competent Hand clipping of each excess lead Excess power turned into heat (danger * 162)

9. Digital switching current source Serves out power using switched inductor No excess heat generated Low power surface mount possible (SMD) Low cost components Small size – 1/8 size of non-SMD Challenge: developing SMD skill in community $486 + 80 person hours

10. Switching LED Driver Prototypes Version 1 – used very small fragile chip which we could not yield stable assembly process for. 60 man hours + 6 calendar weeks = scary Version 2 – used larger chip from different company. Net reduction in parts cost. 40 man hours + 3 calendar weeks Version 3 – similar to version 2 with adjustments to make more stable and easier to make 40 man hours + 3 calendar weeks

11. Money verses time risks 2 variations of final circuit board were ordered due to calendar constraints. Lower risk had minimal change from earlier board Higher risk was greater change from earlier board AND included additional circuit protection and feedback to increase LED brightness by 20% Added cost of ordering two sets of boards $350 saved 2 calendar weeks

12. Training the workers Used electronics kits to train people Basic soldering skills Surface mount soldering and repair Label parts and describe their name and function Designed for debugging On board jumpers to separate each channel Explain the process and risks/likely errors Polarized parts & static/heat sensitivity

13. Production Line Organized from easy to hard First non-polarized then polarized then static sensitive Largest to smallest Each part type placed into a labeled coffee filter and taped to table top. “D” is for Diode People were placed onto line where and explained how their parts were to be placed.

14. Self Organization & Throughput Line workers shifted ownership of parts forward and backward in line to compensate for lags at different stages. 2322 parts were placed by 8 people in 10 hours. (80 man hours) Quality? A total of 3 diodes were placed backwards!

15. Cheap Power Supplies Groovik’s Cube uses recycled PC power supplies. 2 Power supplies are merged together to create redundancy and reduce load. Lower load keeps cooling fans off reducing dust intake. Power merge board has status LED for each power supply board. Failures signal central computer Cube continues to work

16. Plan, Plan, Plan Make a plan Write it down (really!) Send it out for review and input Revise the plan Walk through it with everyone doing the work Execute the plan – avoid feature creep and perpetual revisions

17. Stop changing the Plan A less efficient plan executed by everyone is often better than a more efficient plan executed by a couple people. Coordination is more valuable than last minute efficiency gains that change the plan. Respect the wasted man hours of people standing around wondering what to do. Minimize idle man hours

18. Lessons Learned Surface Mount is cheap and very feasible for quantity production within our community. Keep parts inventory in secure storage dedicated to each project. Much of my time was wasted re-finding project parts. Small bags of parts get moved VERY easily. Locking the parts inventory box is completely reasonable. Consider designs that improve ability to debug and reuse project pieces Cube current source board can be assembled several different ways depending on needs of future projects.

19. Recipe for a Groovik Cube 648 Capacitors 810 Resistors 162 Inductors 324 Diodes 162 Connectors 162 8 pin Chips (IC) 54 Custom Board Arrange ingredients on cookie sheet. Bake at 300 Degrees for 4 minutes. (Set it but don’t forget it!) Remove from oven and allow to cool before removing from pan. Decorate with LEDs, Reflectors, Scaffolding, Software, and Fabric. Share with random dusty people!

20. What’s next? Clearly large scale electronic art projects are possible within our community. What’s next? Who’s taking the lead?