LED strip soaking up power?

I have a simple setup with an UNO, a 4 line LCD screen, an RTC module and a couple relays that I use to switch an actuator. I was playing around with an LED strip today and just running some preliminary tests with my sketch (i.e turning LEDs off and on, changing colors etc). I noticed that when the LEDs are lit, the LCD screen starts to flicker and dim like it's underpowered maybe? Is it the LEDs taking up too much power or something else?

Is it the LEDs taking up too much power

Sounds like it. How long is the strip, how much capacity does your power supply have?

Grumpy_Mike:
Sounds like it. How long is the strip, how much capacity does your power supply have?

Strip is 60 leds long, but even with just half them lit it does it...the adapter I power the Arduino with is a 9V/1.5 A model. So I guess I need a dedicated adapter for the leds too?

30 LEDs @ 60mA per LED = 1.8Amps.

If it is going through the regulator of the Arduino that is only about 600mA you have available. You can run 10 LEDs powering it through the Arduino.

Which kind of LED strip are you using: a WS28xx based strip (like Neopixels), or a 12V LED strip?

Here are some of the differences:

Addressable "NeoPixel" Strips

  • Run on 5V DC
  • Allow you to control each LED individuallly
  • Have 3 wires - VCC, GND, and DATA
  • Usually based on the WS28xx chipset
  • May have separate chips and LEDs, as well as capacitors, mounted on the strip
  • You can cut the strip at any point between LEDs
  • When thinking about power requirements, consider each LED as in parallel with others

Non-Addressable LED Strips

  • Run on 12V DC (usually)
  • Control only at the strip level, not individual LEDS
  • Have either 2 wires for a single color strip, or 4 wires for RGB
  • Strips do not have chips on them.
  • Usually has resistors on the strip
  • LEDs are grouped (usually in 3s), and cannot be subdivided
  • When thinking about power requirements, LEDs are usually grouped parallel groups of 3 LEDs in series

Depending on the type of strip you're using, you'll need to supply a smooth power signal beyond the 1.5A if you want everything on at full brightness. A good general estimate is that LEDs will be consuming about 20 mA each when fully on - thus, an RGB will consume about 60 mA when it's set to white. Depending on the type of strip, you'll need to consider series/parallel arrangements to figure out the max current draw. The internet is rife with tutorials if you need help.