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Ligne 60 : − + Ligne 78 :
Ligne 78 : − === Bloc d'alimentation - les montres de puissance ===+ Ligne 87 :
Ligne 87 : − === Distribuer l'alimentation ===+ + + + + + + + + + + + + + + + + + + + + + + + + +
→Estimation de la puissance nécessaire
The choice of "overhead" in your power supply is up to you. Maximum safety and reliability are achieved with a more generously-sized power supply, and this is what we recommend. Most power supplies can briefly push a little extra current {{underline|for short periods}}. Many contain a thermal fuse and will simply shut down if overworked. So they may technically work, but this is the electronics equivalent of abusing a rental car.
The choice of "overhead" in your power supply is up to you. Maximum safety and reliability are achieved with a more generously-sized power supply, and this is what we recommend. Most power supplies can briefly push a little extra current {{underline|for short periods}}. Many contain a thermal fuse and will simply shut down if overworked. So they may technically work, but this is the electronics equivalent of abusing a rental car.
=== J'ai besoin de 3.6 Amp. Ca ira avec un bloc de 10 Amp? ===
=== J'ai besoin de 3.6 Amp. Est-ce que cela ira avec un bloc de 10 Amp? ===
'''Question:''' I estimate I need a 3.6 Amp power supply. I have a 10 Amp supply on-hand. Will this cause my NeoPixels to explode?
'''Question:''' I estimate I need a 3.6 Amp power supply. I have a 10 Amp supply on-hand. Will this cause my NeoPixels to explode?
As long as the output is 5 Volts DC, you’re golden. The LEDs will only draw as much current (Amperes) as they need. So extra Amps are OK — in fact, it can be a good thing. The larger power supply will run cooler because it’s not being pushed to its limit.
As long as the output is 5 Volts DC, you’re golden. The LEDs will only draw as much current (Amperes) as they need. So extra Amps are OK — in fact, it can be a good thing. The larger power supply will run cooler because it’s not being pushed to its limit.
If you go this route, the key is to have all of the ground pins among the strips connected in common, but the +5V from each power supply should be connected only to one length of NeoPixels — those should not all be joined. Every power supply is a little different — not precisely 5 Volts — and this keeps some from back-feeding into others.
If you go this route, the key is to have all of the ground pins among the strips connected in common, but the +5V from each power supply should be connected only to one length of NeoPixels — those should not all be joined. Every power supply is a little different — not precisely 5 Volts — and this keeps some from back-feeding into others.
== Bloc d'alimentation - les montres de puissance ==
MCHobby propose un bloc d'alimentation 5V continu pouvant fournir jusqu'à {{pl|311|10 Ampères}}. This is usually sufficient for a couple hundred NeoPixels or more. For really large installations, you’ll need to look elsewhere.
MCHobby propose un bloc d'alimentation 5V continu pouvant fournir jusqu'à {{pl|311|10 Ampères}}. This is usually sufficient for a couple hundred NeoPixels or more. For really large installations, you’ll need to look elsewhere.
Please note that '''projects of this scale are potentially very dangerous''', and the problems of power distribution are fundamentally different than hobby-scale projects. As much as we enjoy helping our customers in the forums, they are for product technical support and {{underline|not}} full-on engineering services. If you’re developing a project of this scope, hire a professional electrician with experience in high-power, low-voltage systems such as photovoltaics or large RVs and boats. This is no charade.
Please note that '''projects of this scale are potentially very dangerous''', and the problems of power distribution are fundamentally different than hobby-scale projects. As much as we enjoy helping our customers in the forums, they are for product technical support and {{underline|not}} full-on engineering services. If you’re developing a project of this scope, hire a professional electrician with experience in high-power, low-voltage systems such as photovoltaics or large RVs and boats. This is no charade.
== Distribuer l'alimentation ==
The longer a wire is, the more resistance it has. The more resistance, the more voltage drops along its length. If voltage drops too far, the color of NeoPixels can be affected.
Consider a full 4 meter reel of NeoPixels. With 5V applied at one end of the strip, for those pixels closest to this end, power traverses only a few inches of copper. But at the far end of the strip, power traverses 8 meters of copper — 4 meters out on the +5V line, 4 meters back on the ground line. Those furthest pixels will be tinted brown due to the voltage drop (blue and green LEDs require higher voltage than red).
{{ADFImage|NeoPixel-UserGuide-Alimenter-20.jpg|640px}}
'''Un truc de Pro:''' NeoPixels don’t care what end they receive power from. Though data moves in only one direction, electricity can go either way. You can connect power at the head, the tail, in the middle, or ideally distribute it to several points. Try to aim for about 1 meter lengths for the best color consistency. With larger NeoPixel setups, think of power distribution as branches of a tree rather than one continuous line.
{{ADFImage|NeoPixel-UserGuide-Alimenter-21.jpg|640px}}
=== Distribution sur un projet Fringuable ===
'''Resistance is just as much a concern on tiny projects too!'''
For wearable electronics we like conductive thread…it’s flexible and withstands hand washing. Downside is that it doesn’t carry much current. Here several strands of conductive thread have been grouped to provide better capacity for the + and – conductors down a pair of suspenders.
{{ADFImage|NeoPixel-UserGuide-Alimenter-22.jpg|480px}}
== Piloter des NéoPixels 5V avec un microcontroleur 3.3v ==
Increasingly, microcontrollers are running at 3.3 Volts instead of 5 Volts.That’s great news for efficiency, but can present a communication problem with 5V NeoPixels. The 3.3V signal from the microcontroller may not be “loud” enough to register with the higher-voltage device. The manufacturer recommends a minimum signal voltage of 70% of the NeoPixel voltage.
There are two ways this can be addressed:
* Lower the voltage to the NeoPixels so it’s closer (or equal) to that of the microcontroller. This is why we recommend LiPo batteries for FLORA projects: 3.7V is enough to run a short length of pixels, and the microcontroller is comfortable at that voltage as well.
* Use a logic {{pl|131|level shifter}} to step up the signal from the microcontroller to the first pixel.
{{NeoPixel-UserGuide-TRAILER}}
{{NeoPixel-UserGuide-TRAILER}}