Am a rank beginner. Kind request to anyone out here to help me with this simple question.
I am in the process of creating fading LEDs using Attiny85 programmed from Arduino. My only problem is ....how do I go about supplying power for all 50 LEDs. My 50 LEDs would have to be in series obviously. My LEDs have 4 pins, would that pose a serious problem for a series connectivity?
My power supply would be from AC power supply of 220 V.
Why would they be in series; that's not obvious (to me)? And how would you visualise that?
There is a voltage drop over a led of roughly 1.2V (forward voltage); that would mean that you need at least a 60V output on your power supply.
You will need 3 pins, one for R, one for G and one for B.
You will need a 'driver' (a mosfet will do) for each colour; that 'driver' will need to be able to handle 50 x the current through the led (e.g. 50 x 20 mA).
Each led needs a resistor for each colour.
The product page does not indicate what the forward voltage of the leds is (or I could not find it). Assuming normal leds, that would be in the ange of 1.2V to 1.7V (not checked); in that case you can use a 5V power supply and the current rating should be above 3 x 50 x 20 mA = 3A; buy a 5V/5A. Note that extra bright leds might require more current so you might have to recalculate.
Note that the above approach allows you to control each colour but not each individual led.
You cannot use standard 4 pins RGB leds in series, you need to run them in parallel.
Each led needs a series resistor, this is a total of 150 resistors.
Then you need some current amplification output on the Arduino, a MOSFET transistor for each color is fine for this.
How to connect it depends on the the leds, with common cathode you need p-channel MOSFET transistors connected to +5V and to the RGB pins through the resistors.
My only problem is ....how do I go about supplying power for all 50 LEDs. My 50 LEDs would have to be in series obviously. My LEDs have 4 pins, would that pose a serious problem for a series connectivity?
Could you provide a schematic (not a FritzNutz) of how you plan to hook the LED's up?
Also you might look into doing a search for, on Amazon, "led strip power supply."
Consider that each LED package has 3 LED's you will need to calculate the current requirement of your entire strip.
Also you might want to consider using a LED strip instead of discrete LED's. Search: "arduino led strip lights"
If you use LED strip lights get the power supply based upon the LED strip voltage requirements.
If you can solder there are these that you can amazon search on:
ALITOVE 100pcs WS2812B Addressable 5050 smart RGB LED Pixel light on Black Heat Sink PCB Board for Arduino 5V DC
sterretje:
There is a voltage drop over a led of roughly 1.2V (forward voltage); that would mean that you need at least a 60V output on your power supply.
