Interfacing LDR with 8051

Yeah, I saw that website, its really useful.
But I am required to use a single supply op amp and no relay.
Is there anyway to test a schematic using some software program or something?

@ SkyTerror17
u can operate that circuit with 5 volt
12 volt is for relay
replace a relay and diode with 10k resistor and get logic on the collector of transistor

Oh okay I will try it and update you!

Just asking, what if my power supply is single supply? Does it still works?

@ SkyTerror17
in normal cases single power supply is need connect (-) in schematic to ground and (+) to 5 volt nothing else

Yah, I was alittle confused on that part. I did a schematic and place the components on the breadboard to test it out, still troubleshooting!

The pic below is a new schematic that I just made. I intend to have a 3.3V at the output when LDR is covered (dark) but still having some problems with the output voltage.

@ SkyTerror17
what is the problem u just to tune some values nothing else it should work

I intend to have a 3.3V at the output when LDR is covered.

SkyTerror17

Your setup will be low when the LDR is covered.
Either reverse Vr1 and the LDR or reverse the inputs to the op-amp.

Why drop the output to 3.3 volts ?
R3 and R4 are the wrong way round, and I would use lower values for each.

@majoka
Yeah, everything is almost done. I just have to tune the values of the resistor for R3 and R4 to reach the output voltage that I want!

@ExperimenterUK
Yeah, I swapped the LDR and VR1.
So does the R3 and R4, I even changed the values to 1k for R3 while 10k for R4.
Apologies as my group-mate got the concept wrongly!
We need to drop the output to 3.3V because our 8051 runs on 3.3V.
And we are gonna send a high or low input to it.

So does the R3 and R4, I even changed the values to 1k for R3 while 10k for R4.

SkyTerror17

10k is too high ..
1k and 1.8k would be better.