The prime objective of this article is to know about crystal oscillator module. A Crystal Oscillator Module is often a self contained Crystal Controlled Oscillator, housed in the sealed metal can. It is powered by a 5V DC supply, and usually produces the TTL compatible square wave output signal in a nominated frequency. Some Modules that operate at very good frequencies produce an ECL works output clock. The consistency of operation is possibly printed, or stamped with top of the metal could.