The comparator circuit controls the lighting of a go/no {TAIL ~ go indicator LED}, which instructs {HEAD ~ the operator} as to which side of the readhead is more sensitive to extraneous magnetic flux 
The comparator circuit controls the lighting of a go / no { TAIL ~ go indicator LED } , which instructs { HEAD ~ the operator } as to which side of the readhead is more sensitive to extraneous magnetic flux
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH