Programmable Interval Timer- 8254

The 8254 is a programmable interval timer/counter designed for use with Intel microcomputer systems.It is a general purpose, mulch-timing element that can be treated as an array of I/O ports in the system software.The 8254 solves one of the most common problems in any microcomputer system, the generation of accurate time delays under software control. Instead of setting up timing loops in software, the programmer configures the 8254 to match his requirements and programs one of the counters for the desired delay.
After the desired delay, the 8254 will interrupt the CPU. Software overhead is minimal and variable length delays can easily be accommodated.

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Armature Winding ,Pole Pitch, Coil Span, Commutator Pitch

Now we are going to discuss about armature winding in details. Before going through this section, we should understand some basic terms related to armature winding of dc generator . Pole Pitch Definition of Pole Pitch The pole pitch is defined as peripheral distance between center of two adjacent poles in dc machine. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. This is naturally equal to the total number of armature slots divided by number of poles in the machine. If there are 96 slots on the armature periphery and 4 numbers of poles in the machine, the numbers of armature slots come between two adjacent poles centers would be 96/4 = 24. Hence, the pole pitch of that dc machine would be 24. As it is seen that, pole pitch is equal to total numbers of armature slots divided by total numbers of poles, this can alternatively referred as armature slots per pole . Coil Span or Coil Pitch Coil of

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