text: Not to a pendulum but to control oscillations in a circuit sense, on ecould use a phase lock loop (pll).  Its whole life revolves around using a reference oscillator, locking onto it and outputting a new oscillation of frequency f or some multiplier of f.\nThe major components are as follows\n1) Phase Detector:  It determines if you are locked or not\n2) Charge pump: Produces an up or down control signal depending on the output of the Phase Detector to either speed up or down f\n3)Voltage Controlled Oscillator (VCO):  Takes the up/down control signal from the Charge Pump and produces a new f that is either faster or slower.  This is the output of your new oscillator.\n4)Feedback loop: Taken from the VCO, it is compared with the reference oscillator you started with and determines if the two are locked.  If they are, you have a locked pll and can know that the output from the VCO is a good clean clock.\n\nThis is a reeeeaaaallll basic overview.  Some pll designer will probably come in and correct me!