LED Dimmer circuit needed

LED dimmer circuit please suggest me a good one,my LED is CREE XML LED voltage ratings is 3-3.5V and current ratings is 0.7-3A.Input should be 5Volts.
It should have a variable resistor with switching function.ON/Off potentiometer.
Your early response is welcomed!.?

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iceng6 years ago
Here is a nice circuit using the LMR10520 simple switcher using a
5K pot to adjust the LED current from  700ma up to 2000ma ..  .  A
Faizan Hamayun (author)  iceng6 years ago
Thanks for reply,it their any other IC with DIP package for dimmer function.
Kindly let me know what changes are required for a 555 timer circuit if use as a dimmer.

Kindly let me know if i want to drive the IC with a 5V,3A adpater then what changes are required in circuit like can i use TIP 122 NPN,what diode should be used that is easily available like(1n4007) what should be the value of potentiometer then.And any change in other values of circuit.
frollard6 years ago
That is a high power led. You'll want a current controlled driver - and if you want dimming, you're gonna want a specific driver board. They aren't expensive, 5-10 dollars, and they ensure you can use whatever battery type is appropriate;

Search for flashlight led driver and you'll find tonnes on sites like ebay and dealextreme.

I know it's not a 'put it together' option, but there aren't good portable, dimmable high power led drivers for the layman.
rickharris6 years ago
There is a dimmer cct here using a 555 timer
Faizan Hamayun (author)  rickharris6 years ago
Thanks but if a single LED is to driven and it's current is hihger so what should be the transistor used.
Also if the 555 timer is given 5volt then will this circuit works.