This part is a kind of semiconductor called 2N4870.

Function of this product has Unijunction Transistor.

Manufacturers : Multicomp

Image and pinout :

Some of the text within the PDF file :

Unijunction Transistor Description: A PN unijunction transistor in a TO–92 type package designed for use in pulse and timing circuits, sensing circuits and thyristor trigger circuits Absolute maximum Ratings : (Ta = +25°C unless otherwise specified) Power Dissipation, Pd : 300mW Derate Above 25°C : 3.0mW/°C RMS Emitter Current, Ie(rms) : 50mA Peak Pulse Emitter Current (Note 1) Current, ie : 1.5A Emitter Reverse Voltage, Vb2e : 30V Interbase Voltage, Vb2b1 : 35V Operating Junction Temperature Range, Tj : -65°C to +125°C Storage Temperature Range, Tstg : -65°C to +150°C Electrical Characteristics: (Ta = +25ºC Unless otherwise specified) Parameter Instrinsic Standoff Ratio Interbase Resistance Interbase Resistance Temperature Coefficient Emitter Saturati [ ... ]

2N4870 PDF Datasheet Download