![]() ![]() So yeah, these are two very different options the first step to helping the OP choose which approach to take is to not horribly conflate the two. The downside is that this approach is potentially much more flickery, especially when digital cameras try to look at it. This is what "PWMing it" looks like: Arduino PWM out -> (sometimes optional) MOSFET driver chip -> MOSFET operating in switching mode -> LED strip In this case the MOSFET is almost ways fully on or fully off, and thus wastes very little power as heat, and will generally not require heatsinking. I have a few LED stars connected in series to a constant current power supply of 350ma, which varies its voltage between 3V-36V. More to the point, if someone says "PWM it", the arrangement above is absolutely NOT what is generally meant. bombarie April 10, 2020, 4:26pm 1 TDLR Can I dim a constant-current LED driver by driving PWM to a MOSFET Ive seen nos and Ive seen yesses and my trials give me mixed messages too. Im trying to build a PWM led dimmer with Arduino using this circuit: simulate this circuit Schematic created using CircuitLab. Just a nomenclature correction: what you're describing here is something like this: Arduino PWM out -> RC smoothing filter -> OpAmp buffer -> MOSFET operating in linear mode -> LED strip In this scenario, the LED strip has a fairly constant current flow through it, and the MOSFET is dissipating potentially quite a lot of heat, and will probably need heatsinking. This one comes with constant voltage and constant current(they do have inflated ratings so don't use them to full power but I have used them at 150w no problem) If you have any problems or questions feel free to ask. You could also use a cheap buck converter and use the trim pot to set max voltage and add a separate pot for brightness and they don't use pwm. Just looking at the LED, you shouldn't be. R5 limits the current pulses through D6 to about 1. The data is sent in individual bytes, each of which ranges in value from 0 to 255. Step 1: Circuit Diagram and Description The power supply voltage for driving the gate is supplied by the voltage across the MOSFET. This example shows you how to read an analog input pin, map the result to a range from 0 to 255, use that result to set the pulse width modulation (PWM) of an output pin to dim or brighten an LED and print the values on the serial monitor of the Arduino Software (IDE). I wouldn't bother with rotary encoders unless you need very fine control over the brightness. You adjust the PWM frequencies of the remaining two timer/counter peripherals before you're done with dimmers. This example shows how to send data from a personal computer to an Arduino board to control the brightness of an LED. If you use pwm with an arduino be sure to use the pins with the highest pwm frequency(pins 5 and 6 run at 980hz one the uno) and I have gotten head aches from pwm lights so now I add a smoothing capacitor but if you don't get headaches then don't worry about it. ![]() Chances are the dimmer switch doesn't act just like a potentiometer, but there might be one inside of it that you could use with the arduino instead of a normal potentiometer. ![]()
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