What is difference between 5V and 12V power supply?
I want to power my WS2812B LED light strip (5m at 60 LED/meter) and don't understand why I would want a 400W 5V 80A power supply vs a 400W 12V power supply?
What is the impact of using 5V vs 12V?
Each individually addressable LED on the strip (needs?, accepts?) 60mA and 3V forward voltage.
LEDs don't really have a forward voltage requirement. They have a forward current limit, and that in turn affects the voltage. Current limiting is most commonly done with a resistor, the value is chosen with simple math using the forward voltage drop and desired/maximum current. You can use almost any voltage you want until you reach the sparky levels.
However, the above only applies to raw LEDs. if you are using a manufactured product you must use whatever power the product calls for. If it wants 5V, you buy a 5V supply.
5V is standard USB bus power, so if the product is intended for use anywhere near a computer they will probably build it for 5. 12V is standard in vehicles. Both voltages are popular away from those markets, with the choice often as boring as it matches other things that company makes.
Thanks for giving the part number (of the individual LED); I easily Googled it and found out exactly what you're talking about.
Indeed, these LEDs work on 5 volts DC, as discussed in all their literature. That probably relates to them being individually addressable. Common, whole-strip-the-same LED strips generally operate on 12V, with a few that operate on 24V.
With low Volt electronic A/C transformer, higher voltages are to compensate for the voltage-frequency ratio output on the load side. Typical "puck" light electronic A/C transformer steps up the frequency from 50 or 60 Hertz to around 19,000 - 28,000 Hertz. Manufactures step up the voltage to 24 Volts on their more higher-end products.
Instead of using a low Volt electronic A/C transformer, there is also a low Volt direct current transformer. These do not step up the frequency because they are direct current, but certain installation cautions need to be followed. Namely, the polarity needs to match, and if any dimming of the LEDs are needed, a direct current rheostat has to be installed on the load side of the circuit. Also, I would keep in mind the voltage drop would be an issue of longer runs were to be required. For this case, a higher voltage would be sensible.
A typical LED strip from the hobby store is probably D/C. Keep in mind you cannot mix and match D/C and A/C. You have to stick with what the product is designed to use. I prefer A/C because they work with most existing rheostats and polarity is not a concern.
