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. For 3V nOOds, try around 50 Ohms if the supply voltage is close to 3V, and 220Ω for a 5-ish Volt supplt. 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 and runs for hours…sometimes even a couple days! 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.
-
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.
Page last edited March 08, 2024
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