nOOds are comprised of many light-emitting diodes (LEDs), they have a specific polarity, with distinct anode (“plus”) and cathode (“minus”) ends. If a nOOd doesn’t light, you might just need to flip it. The anode end can be identified by a teeny-tiny hole in the metal end tab.
An inline current-limiting resistor is recommended. Try around 50 Ohms if the supply voltage is close to 3V, and 220Ω around 5V. For brief tests at these voltages you can probably omit this, but for best longevity it’s a smart thing to have.
nOOds can be powered directly off a 3V coin cell such as a CR2032. This won’t be as bright as with a “proper” power source, but for small items and props it’s a great effect. Because these cells are inherently current-limited, no resistor is needed.
nOOds can be powered and controlled from microcontroller output pins via digitalio (CircuitPython) or digitalWrite (Arduino), and the brightness modulated and animated using pulse-width modulation (PWM) via pwmio (CircuitPython) or analogWrite (Arduino). Here are some things to be aware of:
- Though most microcontroller GPIO pins are inherently current-limited, it’s considered prudent to add a current-limiting resistor (as described above) so the chip isn’t continually “redlined.”
- Every microcontroller has different current drive capabilities, with limits per pin, per port, and in total. This information will usually be in the “Electrical Specifications” section of the chip datasheet.
- Some microcontrollers can sink more current than they can source. That is, you might control more and/or brighter nOOds by connecting the cathode (–) end to GPIO pins, and the anode (+) to the microcontroller’s voltage, and use inverted logic. Again, check the chip datasheet.
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Avoid using
analogio(CircuitPython) oranalogWrite()(Arduino) to DAC-capable pins (true analog voltage out, not PWM, such as on the SAMD21 A0 pin); LEDs require current control, not voltage control.
Given the vagaries and differences among microcontrollers, rather than controlling nOOds straight off GPIO pins, consider using a dedicated LED driver such as the AW9523. This ensures consistent peak brightness regardless of the type of microcontroller, and dimming is performed via current control rather than PWM; the light is perfectly steady and photographs well. Current-limiting is performed by the device, so no per-nOOd resistor is needed.
nOOds could also be controlled with a WS2811 driver IC — the same logic that’s inside NeoPixels! This does not make the nOOd per-LED addressable*, but…with three nOOds side-by-side (red, green, blue)…could allow for a sort of color-controllable Neo-nOOd. The WS2811 is a “sink” driver, so the cathode end of each nOOd connects to the IC. The chip provides its own current control (18mA), resistors aren’t needed.
* The highest density addressable item Adafruit carries is this half-meter NeoPixel strip, but it’s much wider and not as flexy as nOOds; not really the same thing.
nOOds can be connected in series (end-to-end) with a corresponding increase in voltage, e.g. 3V for one nOOd, 6V for two, 9V for three and so forth. You’ll still want a current-limiting resistor. Lower voltages might suffice, e.g. two red nOOds might work from a 5V supply…you’ll have to experiment. Probably best and easiest to work with these as parallel, not serial, components.
