NurdNode

NurdNode
Participants
Skills	Electronics, Programming
Status	Planning
Niche	Electronics
Purpose	Fun
Tool	No
Location
Cost
Tool category

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Description

The goal is to build wireless nodes that will control a bunch of LED's for cool lighting effects. The ultimate cool is to build enough, so we can put them in the connector pieces of our geodesic dome

Hardware design considerations

1 node will draw around 1A in current. For 31 nodes, this is obvisouly 31A in current at 5V, making the total power consumption 155W at full load. The current proposition is to bundle the power and signal lines into one cable, and run them in an upward spiraling fashion across each node, connecting them serially. The benefit of this setup is that it allows for easy addressing and it's simple. However, running 31A through a single power line requires a big, heavy and expensive cable.

The length of the power lines is determined at 60m. According to this site [1], at 3% acceptable loss, and using 5V at 31A the cable crossection is 16m2. A ballpark price estimate using Eijlander as supplier is roughly 330 euro.

An alternative would be to devide the power distribution into several groups. The upside is that we can get away with thinner cables, but we may require longer cables.

Yet another alternative is to raise the voltage of the grid to 12+V. This means we may use thinner power lines and still use the serial wiring setup. However, each node will have to be equipped with a switching power source to keep power dissipation at its lowest. This circuit will come at an extra cost, and having 31 nodes, this could escalate quickly.

Parts selection

IRL540 for power led stages?

TODO

Hardware

• Calulate total length of cable required to connect all nodes
• Calculate price of power lines
• Design power circuit
• Design LED circuit (for optional leds)
• Design power stage for 3W led
• Have design reviewed
• Select appropriate through-hole parts for breadboarding
• Assemble BOM
• Order thru-hole parts
• Build thingamagic on breadboard
• Design board
• Select appropriate SMD parts for the final device.

• Have some fun!
• Add more tasks as we go along

Total cable length based on 10M dome = 31 - 1 * 2m = 60m
Eijlander supples 16mm2 wire [2] for 334.80E for 120m (+ and -).

Software

• Create some spiffy code to make the blinkenlichten go blink blink.
• Create a C&C lib that organises the nodes and takes care of the comms between the nodes and the higher level software. I'm thinking REST API for the higher level stuff and UDP multicast for the lower end. Suggestions welcome.
• Find a tool (better yet DIY) a tool that allows you to define an animation in 3D and project it on the geodome.

Links

• Leds: http://www.ebay.com/itm/191388798412
• Or: http://www.ebay.com/itm/221544924178 with added heatsinks onboard.
• Extra heatsinkery: http://www.ebay.com/itm/331286129263
• Sticky pads for connection: http://www.ebay.com/itm/121331880334

• Rectifier: https://www.fairchildsemi.com/datasheets/ES/ES1A.pdf
• XT60 conns: http://www.ebay.nl/itm/100pcs-50-pairs-XT60-Plug-Connector-Heat-Shrink-for-RC-Airplane-Quadcopter-DIY-/261863841242