Mechanic's stethoscope - photo

[Altair]

Mechanic's stethoscope.




Previously:

Teaching stethoscope - photo

[mlochala]

Nothing like the sensation of using one of those to diagnose a weird engine noise and then accidentally bumping a rotating pulley.

[nova_robotics]

I bought one years ago. Works good. Put it against an alternator and you can hear it cogging magnetically as it rotates past each phase.