On http://www.allaboutcircuits.com/vol_2/chpt_13/6.html
Regarding Hall effect sensors, it says
“The voltages at the two outputs are complementary.”
What do they mean by that? Doesn’t a Hall only have (2 power connections plus) one output? And what do they mean by “complementary”?

 

Complementary means opposite to each other. When one output is "high" the other is "Low".

There are 2 Hall sensors in that example.

 

Complementary means opposite to each other. When one output is "high" the other is "Low".

There are 2 Hall sensors in that example.

I see 3 Hall sensors. And since they are 120 degrees apart, how can one be high and the other low?

 

Hello,

In the shown picture is the first one on that page, in that picture the hall sensors have one output.

Later on that page this picture is shown:

In that picture the hall sensors have two outputs that are complementary.

The following page from allegro will tell you about the function of the hall sensor:
http://www.allegromicro.com/en/Desi...ions/Hall-Effect-IC-Application-Guide.aspx#Q5

Bertus

 

Thank you. I get it now. It's simple. I wonder why it took so long for BL motors to catch on?