Hi Folks
I tried building that circuit too, but had numerous problems with it.
I ended up deciding to design my own, I wanted to add the amount of oxygen in blood (SpO2) too. I havent done any formal electronic study for a number of years...so it is extremely difficult for me.
I have good pulse output using 3 stage transistor amp, that currently illuminates an led. The very difficult part is the SpO2 levels.
The pic will have no diffuculty in counting the number of pulses produced by the amplifier output.
I guess the point I'm trying to make is, if this is your in your final year (of course) and your playing with pics, then you should have the level of expertise to design your own.
I have designed my own and its been over 15 years since I did electronics at school.(GCSE) I have only been playing with pics for a couple of months, and have never had any formal training in pics. Granted I'm struggling with one aspect of my design but I'll get there eventually with some help from forums. I use the forums to check my ideas, and to seek help, advice.
I dont use it to rip off other peoples work.
At the end of the day I'm only a hobbyist.
I have to agree with andy257 ripping off someone elses work is a no no!!!!!!
Use other peoples work to discover the theory behind a project by all means, but to simply just copy for a qualification is very sad indeed.
Regards
Kris