When connecting NeoPixels to any live power source or microcontroller, ALWAYS CONNECT GROUND (–) BEFORE ANYTHING ELSE. Conversely, disconnect ground last when separating.
Adding a 300 to 500 Ohm resistor between your microcontroller’s data pin and the data input on the first NeoPixel can help prevent voltage spikes that might otherwise damage your first pixel. Please add one between your micro and NeoPixel.
Before connecting a NeoPixel strip to ANY source of power, we very strongly recommend adding a large capacitor (1000 µF, 6.3V or higher) across the + and – terminals. This prevents the initial onrush of current from damaging the pixels.
Be extremely cautious with bench power supplies. Some — even reputable, well-regarded brands — can produce a large voltage spike when initially switched on, instantly destroying your NeoPixels!
If you use a bench supply, do not connect NeoPixels directly. Turn on the power supply first, let the voltage stabilize, then connect the pixels (GND first).
The triggering in this case is the result of a main power drop and recover. The battery is unable to keep the votage at 9V level at the very moment any led is turned on, the voltage is droped down. That is what makes pin 14 to get the clock pulse so the 4017 shifts to the next led. The moment the led is off and right before the next led is turned on the main power gets recovered. When the next led is on again, the main power drops down, and so on.
I love the “bigclive” YouToube channel: it is full of neat ideas, and wise tips on disassembled electrical gadgets. Most of his videos involve soldering or/and making schematics of the things he tears apart or builds.
Modern LEDs are bright enough at low current to use as directly mains powered indicators with minimal circuitry. The slight downside is that with a simple resistor circuit the vast majority of the power gets wasted as heat. But the current is so low anyway that it doesn’t really matter. Here are some simple ways to drive LEDs from 110V to 240V with minimal circuitry. I tend to recommend running resistors at around half their rating at worst as it means they will last a long time and not discolour too much with age.
His [WayBack] bigclive.com web-site is very small and shows some of his projects.
It actually started as a Dutch site, is ran by a Belgian now living in Barcelona. This means many articles are available in various languages, not just English and Dutch, but many also in French, German, Spanish, and Italian. Some articles are only available in English or Dutch.
[WayBack] Yepkit – Electronics: YKUSH Yepkit USB Switchable Hub (models for USB 2 and USB 3.1 allowing to switch 3 ports at maximum)
[WayBack] Robot Electronics: Relays (both mechanical and solid state) in many communication kinds (ethernet, USB, RS485, TTL, Bluetooth, Modbus, MIDI and DMX) and sizes (from 2 to 24 ports).
The Wiert Corner - irregular stream of stuff 