Can LED strip (from laptop lcd monitor) be used with arduino?

Thread Starter

skopicek

Joined Mar 28, 2020
2
Could the LED backlight strip ( without inverter board) be used and powered with arduino?
I am new to electronics so forgive me my ignorance. But I understand that inverter does change dc from laptop to ac to power lcd. So I am not sure if the led stripe can be powered by dc from arduino. Also it needs 20 V which in arduino case would need external power source since arduino can provide 5 V max. Or is it even possible to power it straight from arduino using only 5 volts?
The connector to led stripe has 9 pins and is labeled:
8FR9B3FS
8FR3A202V
2.jpg
I want to use it for arduino / artsy project. When I broke my laptop screen, I disassembled it out of curiosity and from the waste I created this (orthodox icon inspired) saint of technology. LED backlight strip is used on halo around saints head and (since I want to make this interactive with arduino) it would be very cool if halo could shine.
1.jpg
 

djsfantasi

Joined Apr 11, 2010
6,334
Yes, it’s likely you could use the strip with an Arduino. But you’d have to figure out several things.

1) Why are there nine pins and what does each one do?

2) Are the LEDs wired common cathode (ground) or common anode (power)?

3) Are the LEDs wired in serial? How many LEDs per string’?

4) Assuming the pins light different segments of LEDs, how much current does each pin require?

5) You stated it operated on 20V. It’s unlikely it would run satisfactorily on 5V, but what is the operating voltage range?

A general solution, assuming that the LEDs are wired (or can be wired) common anode (positive side of the LED connected in common) is to use an n-channel logic-level Power MOSFET(s), controlled by an Arduino digital pin, which switches ground to the LEDs. It’s dependent on the current draw and voltage required of the LEDs. If the current is less than 200mA, you could use a 2N7000. Otherwise, the power MOSFET is necessary. Sparkfun has one that might work
(https://www.sparkfun.com/products/10213)

If the 9 pins are ground and 8 different strings of LEDs, you can use 8 pins on the Arduino and 8 MOSFETs to individually control the LED strings to adjust brightness.

In this simple case, the Arduino pin would connect to the MOSFET gate. I recommend also connecting a 10k resistor from the Arduino pin/gate to ground. And to be super safe, insert a 220k resistor between The Arduino pin and the gate.

If you want to switch the 20V side, it is a little more complicated. You need a p-channel Power MOSFET switching the 20V to the LED strips. And you’ll need an n-channel logic level MOSFET as a MOSFET driver. The wiring is more complicated, and if you determine that’s what you need, we can discuss it further.

The n-channel MOSFET approach is used often in switching things from an Arduino. Hence, it’s useful to learn the technique. I had PCB boards made to contain several of these circuits for future projects.
 
Top