Does Nightcore use PWM?
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I have gone looking for it, shining the beam on spinning fan blades and waving it around on the lowest setting. I have not seen one little bit of flicker.:twothumbs
I believe I read somewhere that the PWM frequency in the NDI (my light) is 7800 Hz, which supposed to be way too fast for the human eye to detect.
I believe I read somewhere that the PWM frequency in the NDI (my light) is 7800 Hz, which supposed to be way too fast for the human eye to detect.
Marduke
Flashaholic
Most lights which uses "infinite variable brightness" uses PWM. However most lights are set well above the perceptible threshold of any human except at the lowest intensity in the most specific circumstances.
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TigerhawkT3
Flashlight Enthusiast
Nope, some dimmable lights actually use constant current with no PWM. Examples are the Gatlight, Titan, any mod with a Shark, and any mod with an LM317 or LM138.
But yeah, most of them, especially the affordable ones, use PWM. I'm very sensitive to visible PWM, but the Nitecore lights (as well as Liteflux, BTW) give me no problems.
Tohuwabohu
Newly Enlightened
The PWM frequency of both my Nitecore EX10 and Nitecore Extreme is somewhere in the 37kHz to 38kHz region. I can't see it, I can only detect it with a photodiode and my USB-scope.
But sometimes I notice a slight flickering/pulsing of the EX10 at low setings.
I think that is an effect of the boost circuit working at a variable frequency and the PWM circuit working at a fixed frequency.
I tried to explain it here with lots of scope graphs here.
But sometimes I notice a slight flickering/pulsing of the EX10 at low setings.
I think that is an effect of the boost circuit working at a variable frequency and the PWM circuit working at a fixed frequency.
I tried to explain it here with lots of scope graphs here.
I don't know what's your definition of PWM.
Basically, there are two ways to turn a certain voltage into another. The one is called "Linear", and the other called "Switch". The way the first tech accomplishing the goal is to turn the unwanted energy into heat. For example, if you want to get 3V output from a 5V input, and the current is supposed to be 1A, a linear circuit will absorb 5W from the input, turn 2W into the heat, and then there will be 3V 1A output. Of course this is quite an unefficiency way.
The other is switch. To be easy to understand, you can imagine that in switch circuit, there is a "pool" that can contain energy. If output is lower than input, the circuit just first get a pocket of energy from the input, and put it into the pool, and then transform it to the output. Generally it is like this, and PWM is only one mode of switch circuit, there are others like PFM etc, but they are not important to this topic.
So every torch with MCU-controlled brightness adjusting does use a switch circuit(PWM or other). If a torch uses low frequency PWM driver and directly drives the LED, the LED will flicker. However if a torch uses a high frequency PWM driver that directly drives the LED, will not make human feel flicker due to human eyes is not that sensitive to high frequency switches. Or, a PWM driver with low frequency can add a capacitor between the LED's positive pin and the nagative pin to remove the flicker.
So...I think you may talking about flicker, right?
Basically, there are two ways to turn a certain voltage into another. The one is called "Linear", and the other called "Switch". The way the first tech accomplishing the goal is to turn the unwanted energy into heat. For example, if you want to get 3V output from a 5V input, and the current is supposed to be 1A, a linear circuit will absorb 5W from the input, turn 2W into the heat, and then there will be 3V 1A output. Of course this is quite an unefficiency way.
The other is switch. To be easy to understand, you can imagine that in switch circuit, there is a "pool" that can contain energy. If output is lower than input, the circuit just first get a pocket of energy from the input, and put it into the pool, and then transform it to the output. Generally it is like this, and PWM is only one mode of switch circuit, there are others like PFM etc, but they are not important to this topic.
So every torch with MCU-controlled brightness adjusting does use a switch circuit(PWM or other). If a torch uses low frequency PWM driver and directly drives the LED, the LED will flicker. However if a torch uses a high frequency PWM driver that directly drives the LED, will not make human feel flicker due to human eyes is not that sensitive to high frequency switches. Or, a PWM driver with low frequency can add a capacitor between the LED's positive pin and the nagative pin to remove the flicker.
So...I think you may talking about flicker, right?
You're referring to (switching) boost circuits.
There are other types of regulated power supplies out there...
Also, not every MCU controlled driver uses PWM. Shark/Remora combo uses PWM to control the driver, but the output doesn't pulse - it's (constant) current regulated. Arc6 uses a combination of PWM and current regulation - some levels use the former, some the latter, some both. Spartanian II uses PWM for lower levels and current regulation for upper levels. Etc.
There are other types of regulated power supplies out there...
Also, not every MCU controlled driver uses PWM. Shark/Remora combo uses PWM to control the driver, but the output doesn't pulse - it's (constant) current regulated. Arc6 uses a combination of PWM and current regulation - some levels use the former, some the latter, some both. Spartanian II uses PWM for lower levels and current regulation for upper levels. Etc.
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