Ok, so I finally got around to making my first prototype and the results were mixed. As a note, I couldn't find the TI TLV3072 that he was adamant on using and so instead opted to try using a basic LM393 comparator. Seems to have done the job. Now the results:
Even though I follow his circuit to the T, my circuit did not give me the same results as his. For a starter, my LED is on all the time rather than off, ie it turns off when the laser is pointed at the LDR rather than the other way around. I'm pretty sure this is a simple fix but I'm struggling to see where I made the mistake since I followed his circuit.
Secondly, my circuit acts in the same way as his in the sense that ambient light no longer affects my circuit. However, while both of his LDR acts a switch, only one of mine does. Now this is actually quite fortunate for me because it means that one of my LDR acts as a comparator for ambient light but at the same time it doesn't.
Wait what?
Yes it puzzled me too. While his LDRs always had to be in the same environment, my LDRs does not. This is fortunate for me because to be honest, I only wanted one LDR showing and the other one hidden.
Now here is the hard part, is any of you able to explain to me how my second conundrum is possible? Because I've thought it through and it just doesn't quite make sense to me. I've tried removing the non-acting LDR (replacing it with just a wire) and without it, my circuit no longer takes out the effects of ambient light, meaning that it is having an effect, albeit a different one. If any of you guys can explain it to me, it would be much appreciated.
Thanks guys!