which circuit can i use to dim LED bulb that was around 7-10W.. i was thinking of PWM, can anyone suggest the best PWM circuit that is available in amazon?
Search for "[u]dimmable constant current LED power supply[/u]"
These are used for powering "raw" high-power LEDs. The industry standard is a 0-10VDC dimming-control voltage, although some will work with 10V PWM. In either case, you'll need a transistor or MOSFET and a ~10V power supply to boost Arduino's 5V output. And if you need DC, you'll need to filter the PWM.
If you are using an "LED light bulb" from the hardware store, designed to run from 120 or 240VAC house current, you need a regular AC light dimmer circuit. These are something like PWM, but it's synchronized to the power line frequency, so it's a bit trickier. And, both the phase detection and the control pulse must be isolated from the power line voltage.
All "raw" LEDs are dimmable with a variable* current source. LED light bulbs have additional circuitry they must be labeled "dimmable".
- It's called a "constant current" power supply even if the current is adjustable, because the current is controlled and the voltage "falls into place" depending on the load. This is basically the opposite of how a normal power supply works.
The industry standard is a 0-10VDC dimming-control voltage, although some will work with 10V PWM.
Doesn't that mean he either needs to add an RC LP FILTER or a dac + the RC LP FILTER ?
(see Reply#10 in this thread.
For the Arduino, an R value = 3.9K and a C value = 0.1uF works well for most applications.
PLUS a Single Supply ,Gain of 2 , op amp Non-Inverting Amplifier running off +12V ?