In this work, we made a simple electronic tool called a 'magnetic polarity detector' which can determine the magnetic poles of permanent magnets or electromagnets. We used it in some student experiments in the physics laboratory. For example, determining the magnetic poles of permanent magnets and a current-carrying coils or electromagnets. Although this instrument is made of cheap materials and is very simple, we have found that it works quite well in the laboratory and contributes to the demonstration of magnetic poles. We think that it will be useful in examining the magnetic field created by a current-carrying coil and teaching the right hand rule. Therefore, a simple tool that aids in the physics lab, we think it would be useful to use as a tool.