In this circuit, the output voltage will increase in magnitude as there is a voltage present at the input.
This is time dependant as well as voltage dependant at the input, so 500mV for 1 second will produce a lower output voltage than 2V for 1 second.
Flick the switch to see how 2V makes the output increase very quickly whilst 500mV takes a long time!
This circuit can be used for many things, an example being monitoring radiation. this will monitor the amount with time, giving you your exposure in places such as a nuclear power plant.