The PT-1 provides a simple and easy way to determine the relative polarity of coil windings. It allows for an in-process test that takes a minimum of time to perform. By placing a coil on the platform and making connection to the start and end of a winding, a test signal is induced in the winding. The induced signal is low level and completely safe for the operator. By comparing the test signal phase of the coil under the test output, the relative polarity is indicated by the Red/Green LED. The tester operates by inducing a signal voltage in the coil under test by means of a magnetic flux field. The field is generated by a coil located in the probe base. The coil configuration is designed to provide optimum field distribution. We have also applied this basic circuit to a 5-channel scanning unit.