Heart-Sound sensor

I need to know if the heart-sound sensor follows the same schematic of the Piezoelectric pulse sensor below.

I’ve connected it using the same connection. Seems to work when I put it on my neck, but no response other places. Anyone else tried succesfully? I don’t really see any difference on the two sensors. I bought both, and they seem very similar. Is it really a different sensor?

Here’s another link on the same sensor:


I bought today these sensors, I hope I get them soon…
Is there a schematic of the amplifier circuit used in this type of sensors?
I haven´t found anything in the wiki.

please help