Oscilloscope comparison test.

The shape of the wave depends on the period of the input and the Tau (ie RC constant). If you want a square shape here, then you could alter the period setting in the logic source to be 10ms or 100ms etc, and slide the EC scope timescale till it reads as say 200ms there. It's mostly a matter of understanding the tau for this setup. http://everycircuit.com/circuit/5746890721984512

I will try that tonight, but it looks like you will be 100% correct! I'm embarrassed that I messed up my period input and must have been staring at it for a lot longer than I'm willing to admit. Thanks for your help!

Unfortunately my oscilloscope does not show what it should according to the app. However I'm connecting to my prototyping board so there may be something going on there that is not visible from the schematic. What I will try next is to put the circuit by itself on a bread board and see if I can get that to show up the same as the app. This is all just an experiment to see how close the oscilloscope and app graphs align. I'm hoping to change the capacitor and resistor and see the rise and fall curves look the same. I'm guessing the app would be using standard electronic formulas so it should plot accurately?

@sparkswillfly ... The EC app seems pretty good at showing these sort of details as they should be. I have re-arranged your schematic to show the circuit more clearly with the LED now switched out, because the parameters of the EC LED may present differently to that of your board LED. I have also altered your 150 resistor to be 20k so that the RC tau is now 10 times greater than the period time of 2ms. With that alteration we can clearly see that we have a passive integrator network here which shows a nice triangle output from the 50% square wave (positive only) input. The triangle should settle at 2.5v centre, being half of your 5v pulse input, and the peak here is about 50mV either side of that centre. You board setup really ought to show something very similar (probe compensated etc). You could then switch in the LED of each (as per reqd. resistor adjustment), and see how they differ. http://everycircuit.com/circuit/6717515548590080

Thanks 2ctiby I'll give that a try tonight (Australian East Coast time) when I get home. I appreciate your time helping me out here!

I'm close to what it should look like but I'm generating the logic pulse from a uC and a transistor which may be altering things slightly as current does not want to flow back through the transistor but appears to in the app. Not too sure how to copy the square wave signal you have, perhaps a 555 timer instead?

I guess with the 20k ohm resister there I could run straight from the uC port without any trouble.

One way or another, you will probably need to obtain a good square wave at the start. Here is a version of a 555 being used for your setup ... but you may need to fiddle around with the component values to get what you are after. http://everycircuit.com/circuit/6197037318799360 variable op-amp multivibrator is another option.

After the triangle trace has settled at 2.5v centre, you could adjust the 20k resistor down to zero and watch the trace shape alter through the usual curve (cap charging) shape towards the square shape of the input. That alteration happens due to the period time taking a comparatively larger slice out of the RC tau time now that R is lower, and so making the charge curve more visible.... rather like looking at a straight road (the triangle sides), compared with looking at the Earth curvature (the larger curve section).... Getting a nice triangle straight sides shows a good integration of a square wave.... If that triangle were to be put in to a second RC setup (instead of your LED), then the triangle would be integrated nicely in to a nice sine wave shape. A not-so-good triangle would not give such a nice sine wave shape, and so a third similar RC setup may need to be added to improve the sine shape.(eg if we were aiming to get a good sine shape, as for a Low Pass Filter). http://everycircuit.com/circuit/6126518183657472