Question: [![enter image description here](https://i.stack.imgur.com/Hio4d.png)](https://i.stack.imgur.com/Hio4d.png)

Hi Guys .. I am designing a few panels using LEDs for backlighting. Some of these panels have over 20 leds, using a 5v power source. So only one of these panels can draw around 500mA alone. I am planning on using the same PSU to power them all, but need a dimmer circuit to dim them all at once, but most of the dimmer circuits I have seen can only really do lower current draw, i.e. 2N2222 can only handle 800mA.

Any idea if this is possible with one high current dimmer, or do I have to build multiple dimmers ?

Answer: 
Pulse width modulation (PWM) is the most efficient way to do this. The basic principle is that you cycle the LEDs on and off at a speed fast enough that the eye can't detect a flicker - say 50 times a second. By varying the % on-time from 0 to 100% the LEDs can go from 0 to 100% brightness. The advantages are:

* The power circuit is very simple.
* No power is used while their off.

We need to know what is going to control the dimmer if we are to provide further information.
As far as using the same psi for everything, i would multiplex the banks of LEDs. This way you only power one at a time, but they would all "appear" on but you would only power one at a time