All Vernier EKG sensors have proper isolation. The electrode inputs are isolated from the power supply for the sensor.
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Below are some suggestions for improving the readings you get from the Heart Rate Monitor:
A) Do not move while taking data.
B) When you first begin taking readings, wait a minute or so for the signal offset circuit to adjust.
C) Sitting ...
The adjustable end stop was not designed for anything beyond gentle collisions when using the magnets. The track-jumping behavior is expected.
To use the end stop with higher-speed collisions, remove magnets from the end-stop, and use the plunger ...