PWM vs. variable DC voltage

We're working on a project here and I decided to implement the use of an Arduino with Pin 3 active with a variable PWM to create a distribution between 0 - 5v at the user's request.

Are there any major differences between using PWM vs standard variable voltage that we may run into? Such as, if we were to put a 3v PWM on an oscilloscope vs. a 3v voltage regulated output, would we see any major differences?

I'm just kind of iffy on the whole 'PWM' thing for it being a good source of DC voltage that can be adjusted.

PWM is a digital signal that switches from 0 to 5V. The "pulse width modulation" part comes from how long that signal stays switched ON (at 5V). So it isn't a variable voltage. You can put a low-pass filter (a simple LC filter) to filter out the signal to simulate a DC voltage. However, it won't have any, well very little, current capability.

If you just want to look at the signal on an oscilloscope, it will be completely different. If you want an led to get brighter and dimmer, etc. it will be just like a variable voltage.

What is your real question? What do you want it to do?

Don't try to use it for a solenoid or relay (mechanical devices don't work to fast), but many things will be just fine such as motor speed control, light fading.. etc.

You could use a digital potentiometer (siting on the adjust terminal (eg lm317 or a programmable shunt) as a voltage divider...

Using pwm to control the voltage say with a capacitor to produce a voltage then feed it into a Pass transistor.

You could use a digital potentiometer (siting on the adjust terminal (eg lm317 or a programmable shunt) as a voltage divider...

Luckily you only need 0-5V...

Be very careful in your selection of digital potentiometer in this case since many of them are only 0-5V tolerant devices. The digital pot will be subjected to the output voltage of the LM317 regulator as well as the current used by the IC since it will be in the path to GND. An LM317 will only operate down to 1.25V so if you really needed lower voltage... take that into account... you may need to toss out the idea...

Also...

If you ever needed to go higher than 5V output with the pot and LM317 , you would need to consider a digital pot controlling the input to an inverting operational amplifier with a gain of about 5 to get the range used in a common LAB supplies, IE; 1.25-24V.