Is it safe to use PWM to simulate the 1.6v and 2v for LEDs? That's the voltage the left strip driver is making per my vmm
The way you phrased your question I'm assuming you are asking if you can drive an LED directly from a voltage source using a PWM output (perhaps an arduino output) without using a series resistor. If that is not the case then ignore the remainder of this post.
No it is not.
Assuming you are using a 5v source PWM' to "appear" like the 1.6 Volts you will have two problems.
Look at how PWM's work PWM
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if you are PWM controlling a 5V source. You set the PWM to be ON 32% of the time. The Average will be ~1.6 Volts (0.32 * 5 = 1.6) However the output will be at 5V 32% of the time, during this time the LED will be damaged.
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You cited LED voltages of 1.6 to 2.0V We know LED voltage changes with temperature. So if your LED requires 2.0 Volts and you are supplying 2.0v. If the conditions change and the same LED now only needs 1.6V you again will damage the LED by giving it too much power.
I tried to keep the above simple. In actuality an LED requires you to control the current.
You have to size a series resistor to limit the LED current to its rating at the voltage you are supplying. If you use to much current (anything over rating) will cause failure of the LED. This can be instantly to years. To calculate the resistance you subtract the LEDs Vf (Voltage forward)from the supply voltage to calculate the resistance. There are on line led voltage calculators that do this. All PWM does is turn the output on and off at a predetermined rate. This is the PWM frequency. It also changes the on time in relation to the off time by a percentage (duty cycle) that can go from 0 to 100% 0 to 255 in the Arduino Uno). The apparent brightness is derived from the persistence in the human eye, same as a movie works. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Thanks. I suck at math but I have LED calcs.
It is a led light strip so I'll have to use quite a few resistors.
What LED strip do you have?
Usually LED strips have those resistors in place and are designed to be powered at a specific voltage (commonly 5, 12 or 24V), or they're directly addressable LEDs. Do give more info on your strips.
Also LEDs are current driven, not voltage driven, but as we usually have voltage sources you need some form of current control (such as those current limiting resistors).