I'm sorry but this is incorrect. The number you get from the analogue read shows the strength of how hard you're pressing on the piezo element. To get the heartbeat, you want to measure the time between two spikes (where the pressure on the piezo is higher). How could the arduino possibly calculate the BPM if it doesn't factor in the time? I can see the data you got looked realistic, but that's just a coincidence.
Getting Started With Electronics
Tools + Supplies
Infinity Mirror - Simple an...View Instructable »
Thanks! No, the light is not that crisp, it's more diffused. Plus it's more on the side rather than in front of you.
Thanks! You can also have multiple EL wires in different color and use whichever you're in the mood for.
Glowing Hoodie (Machine Was...View Instructable »
Wireless Home Alarm System ...View Instructable »