Here is another interesting circuit based on a PIC microcontroller. This time, the PIC16F877 is put to measure the beats per minute of the heart, and hence say if you are angry or not. I could add as well "if you are running or sitting", or "if you are scared or not", of if you just met the man/woman of your life... Anyway, the circuit uses the same technique as an older post (from embedded-lab) to measure the beats per minute, with an IR transceiver pair. I liked this method a lot, and so i feature this project to refresh your memory.