This part is a kind of semiconductor called BT134-600.

Function of this product has TRIAC.

Manufacturers : SemiHow

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Some of the text within the PDF file :

BT134- 600 BT134-600 4 Quadrants Sensitive TRIAC FEATURES  Repetitive Peak Off-State Voltage : 600V  R.M.S On–State Current (IT(RMS) = 4A)  Sensitive Gate Trigger Current - 5[mA] of IGT at I, II and III Quadrants. - 12[mA] of IGT at IV Quadrant. VDRM = 600 V IT(RMS) = 4 A ITSM = 33 A IGT = 5mA/12mA Symbol TO-126 Applications Heating control, Lighting control, Motor control such like dimmer, sensor light, Humidifier, etc. General Description Semihow’s sensitive TRIAC product is a glass passivated device, has a low gate trigger current, high stability in gate trigger current to variation of operating temperature and high off state voltage. It is generally suitable for power and phase control in ac application. Absolute Maximum Ratings (TJ=25℃ unless otherwise specified ) [ ... ]

BT134-600 PDF Datasheet Download