Abstract: A thin film magnetic data transducer which prevents capacitive coupling between the transducer and the disk of a disk drive system, has a magnetic circuit which is maintained at the same potential as the disk, usually ground potential. With the disk and the magnetic pole tips of the magnetic circuit at the same potential, capacitive charging and consequent current flow or arcing or discharge noise between the two are prevented. Noise from current due to the variable capacitive coupling of the coil to the disk during disk rotation is also eliminated. The thin film magnetic transducer is fabricated by depositing successive layers of an electrical insulating material, a magnetic material, insulating material, electrical conducting material for a planar coil, insulating material and magnetic material, in the order named on a substrate.

Abstract: A digital phase lock loop utilizing a programmable delay line to phase shift the output of a crystal generated reference clock signal and lock it to digitized data transitions recorded on a suitable medium is provided. The output of the delay line is compared to the digitized data transitions in a phase detector to determine if the delay line output leads or lags the data transitions. The delay line is then reprogrammed to reduce the phase difference between the data transition and the delay output to a minimum value.