Signal reproducing circuit for magneto-resistive head including control circuit for reducing transient period between write period and read period

A signal reproducing circuit comprising:

• first and second power supply lines having different potentials;
• a magneto-resistive effect head having one end thereof coupled to the first power supply line, for reproducing data recorded on a magnetic recording medium in a read operation;
• a first constant current source coupled between another end of the magneto-resistive effect head and the second power supply line, for supplying the magneto-resistive effect head with a sense current in the read operation;
• first and second transistors having collectors thereof coupled to the first power supply line, respectively, and responsive to voltage signals obtained from the one end and the another end of the magnetoresistive effect head, respectively;
• second and third constant current sources coupled between each emitter of the first and the second transistors and the second power supply line, respectively, for supplying the first and the second transistors with a first predetermined constant current, respectively, in the read operation;
• a capacitor connected between the emitter of the first transistor and the emitter of the second transistor;
• fourth and fifth constant current sources between each emitter of the first and the second transistors respectively and the second power supply line for increasing the emitter currents of the first and the second transistors to a second predetermined constant current during a predetermined period in a transition from a write state to a read state;
• and
• a timer circuit which starts its operation when a read/write control signal is changed in level in the transition from the write state to the read state and which controls the fourth and the fifth constant current sources to be brought to an ON state during the predetermined period.