Shaft Rotation Direction Change Sensor Needed

Thread Starter


Joined Jul 7, 2009
I need a sensor to detect a change of direction in a rotating shaft. When the sensor detects the sudden change in direction it would trigger action of an electromagnet. The sensor would monitor either the shaft or a disk attached. A 12 volt dc power source would be used in the circuity.


Joined Jan 18, 2008
It sounds like you are trying to make a electromagnetic brake. You can tell direction of something like a winch drum very simply using one magnet on the drum and two Hall sensors. There are some limitations/restrictions to that method, as it is based on measuring a simple time interval. However, if you think it might be applicable to your problem, let us know here, and I will post more detail.



Joined Aug 7, 2008
Read: AAC, Vol., IV, Digital, Ch. 11, Counters, Synchronous. last paragraph for inf. on shaft encoders.If the code disc is half black, it will take 1/2 turn to detect direction change, to detect sooner, need more segments.