1015 – Ausbausystem: PLL – Technik (PLL Technology)
The phase locked loop technology is a very common and useful circuit. It is used to control the frequency of an oscillator so well that it will always coincide exactly with the frequency and phase of a reference oscillator. Special blocks were designed for this model and include a 4 bit binary counter, an astable / monostable multivibrator, and an optocoupler.
A nice facet to this model includes a fiber optic cable (shown above) which couples the LED block and transistor opto block.
The instruction manual can be downloaded/reviewed here.