BD139 NPN Bipolar Medium Power Transistor 80V 1.5A TO-126 Package

This is a 8MHZ Crystal. This is a low cost crystal oscillator with?oscillation frequency of 8Mhz. Crystal are normally required to provide?clock pulses to your micro controller or other IC's which require external clock?source. An oscillator crystal has two electrically conductive plates, with a slice or?tuning fork of quartz crystal sandwiched between them. The crystal oscillator?circuit sustains oscillation by taking a voltage signal from the quartz?resonator, amplifying it, and feeding it back to the resonator. Quartz has the?further advantage that its elastic constants and its size change in such a way?that the frequency dependence on temperature can be very low.