Really big projects might exceed the current rating of a single power supply. If a larger single power source isn’t available or is beyond one’s budget, it’s possible to split up power demands among multiple sources.
This isn’t just for big architectural installations! It’s also handy with really extravagant wearables, cosplay, art bikes and other mobile contraptions. USB power banks are affordable, ubiquitous and reasonably safe…but each USB-A port can only sustain 1–2 Amps of current. By splitting demands among multiple ports and/or multiple power banks, ambitious portable projects can be build with relative ease (albeit with lots of batteries to top off).
The number and capacity of power supplies will require some estimation on your part, and testing and measuring smaller sections of a project in isolation to determine overall needs and how to split things up.
Let’s imagine a hypothetical situation where it’s been determined that power requirements can be split across three sources (whether that’s power bricks or USB batteries is immaterial). One power supply will feed two strips, the other two will feed three strips each. (Conceivably a project could be split all eight ways, but let’s keep the example manageable!)
Here’s a schematic diagram of how the parts connect. It’s laid out to make all the connections clear, though the actual physical wiring will likely take a different shape…and might have JST plugs on the strips, etc.:
As usual, the example shows NeoPixel strips, but any NeoPixel-compatible part could be used.
Notice there are three groups of strips, each group powered from its own 5V supply; there are no direct connections from one group or one power supply to the next, each is in isolation.
However…each group has a single ground connection to the SCORPIO board (shown as gray wires). As explained on the prior page, this isn’t for delivering power, but to provide a common point of reference through the whole circuit.
Also like the prior page, power to the SCORPIO board can be provided one of three ways:
- (A) above: Through the USB port, either from a USB hub, phone charger, or (with USB power banks) a USB cable into a second or third port on the battery. This is usually simplest.
- (B): a LiPoly battery plugged into the JST connector. Perhaps for portable projects, if you don’t want to tap into the same power source as the NeoPixels.
- (C): connect USB and GND to one of the NeoPixel 5V supplies. If you go this route, unplug the power supply when connecting USB to program the board.
Read the “Single USB Port” page regarding the protection circuit in USB power banks. Allow some safe overhead; don’t “redline” the circuit or your dramatic reveal might get cancelled!
If it’s your first time building a large NeoPixel project, please familiarize yourself with the Power Topology page of the 1,500 NeoPixel LED Curtain with Raspberry Pi and Fadecandy guide. The key point here is to use adequate conductors for carrying power. Wires that are hot to the touch are a fire hazard and a sure indication of inadequate gauge.
