How to connect a Potentiometer to a USB LED Strip to control brightness

I have a couple of potentiometers lying around range from 1K to 500K, I've tried to connect them to a USB Xmas light strip to control the brightness. Below are examples of the issues:

1. When a 1K (or a similarly low resistance pot) is used while the pot is set to the lowest resistance the LED will light, when the pot is turned to the higher resistance the LED will follow the turn and gradually dim, but when the pot reaches the lowest resistance end, the LED strip still has very dim light. So in this case the control dial of brightness works at full range, but the problem is it doesn't turn completely off.

2. When a 200K (or similarly high resistance pot) is used, same case while the pot is set to the lowest resistance the LED will light, when pot is turned to higher resistance the LED doesn't brightens up as responsive in the first three quarters of turn until the last quarter then the LED has became too responsive, very slight turn will brighten LED from little dim to very bright, and there is very little graduation of brightening the LED.

Please help so when the pot is at highest resistance the LED will completely turned off, and as I turn the resistance higher hope that the LED will brighten up gradually to the lowest resistance end.

Many thanks

Duck

 

Thanks Harald for the quick reply and very useful resources.

I've found some pwm controller module (0-5V) on eBay, I guess the easiest way is to use these controllers and just connect the USB light and power USB to this board right ?

Thanks

 

Added the PWM controller I've for reference.