VTR CONTROL HEAD DRIVER

摘要

PURPOSE:To keep a recording current for the control track of a VTR constant and to stably perform magnetization by keeping a current being allowed to flow in a head coil constant. CONSTITUTION:Constant current sources 16, 18 are provided that are the constant current sources to make PNP TRs 1, 3 into constant currents and which supply the base currents for diodes 5, 8, 10, and 13, NPN TRs 6, 11, constant current sources 15, 17, and npn TRs 7, 12 which drive npn TRs 2, 4 that are drivers, and the TRs 2, 4. Then, the PNP TR part of a current driver to allow current to flow in the head coil 20 is made into the constant current. Therefore, the current in the head coil 20 can be kept constant even when a source voltage is fluctuated or the resistance of the head coil itself is fluctuated. In such a way, it possible to permit the current to flow in the head coil 20 and to stabilize the magnetization of a control track.