I built this circuit on breadboard and came across a problem:
I'm using the MCP6001 op-amp with a single supply, configured as an inverting buffer. That's why I connected the non-inverting input to a virtual ground made between R3 and R4. The pot R5 is used to change the input voltage. The LED should get brighter as the input voltage goes down.
It does work in principle, but the LED is less bright than when I connect it to 5V directly. When measuring the voltage at out, it is 0V when the input from R5 is high (5V). But when it's low (0V), the voltage at out will be something like 3.2V. When I disconnect the LED, removing the load from the op-amp output, all is fine and an input of 0V will result in a 5V output.
Does this mean the MCP6001 is unable to properly drive a single LED? I read the datasheet but wasn't able to make sense in such a way that I could determine the maximum output current in my configuration.