Category Archives: Diploma


Switching and linear regulator use fundamentally different techniques to produce a regulated output voltage from an unregulated input.Each technique have advantages and disadvantages.So the application will determine will determine the moist suitable choice.

Linear power supplies can step-down an input voltage to produce a lower output voltage.This is done by operating a bipolar transistor or MOSFET pass unit in its linear operating mode.

Operating in this mode means that there is always a headroom voltage.Vdrop,between the input and the output.The linear regulators are 35 to 65 percent efficient and linear are cost-effective in step-down applications.

A low drop-out (LDO) regulator uses an improved output stage that can reduce VDROP to considerably less than 1.0V.This increases the efficiency and allow the linear regulator to be used in higher power applications.Designing with a linear regulator is simple and cheap,requiring few external components.A linear design is quieter than switcher since there is no high-frequency switching noise.

Switching power supplies operate by rapidly switching the pass units between two efficient operating states that is CUT OFF,where there is a high voltage across the pass unit but no current flow.

And the second is SATURATION,where there is high current the pass unit but at very small voltage drop.Switching power supplies are much more efficient,ranging from 65 to 95 percent.

The downside of a switching design is that it is considerably more complex.In addition,the output voltage contains switching noise,which is must be removed for many applications.

Although there are clear differences between linear and switching regulators,many applications require both types to be used.For examples,a switching regulator may provide the initial regulation,and then a linear regulator may provide post-regulation for a noise-sensitive part of the design,such as a sensor interface circuit.

What is a recorder

A recorder is a measuring instrument that display a time varying.Signal in a form easy to examine and re-examine,perhaps long after the original signal has ceased to exist.In other word a recorder is a device whose function is to record the value of quantity as it is being measured.Such device may include graphic recording devices,computer printers,tape recorders,or cathode ray tube.

Recording preserves the experimental data in a manageable and usable form.A recording system is very useful as (i)It preserves information which could be obtained at any instant from indicating instruments and (ii)It gives informations about waveforms and transient behaviour or phase relationship in different parts of a circuit.

A recorder records electrical and non-electrical quantities as a function of time or relates two signals to each other.Electrical quantities,such as current,voltage etc.,can be recorded directly while non-electrical quantities,such as pressure,temperature,speed,flow etc.,are recorded indirectly by first converting them into the form of electrical signal with the help of sensors or transducers.

Recording devices are of two types namely (i)analog recorders and  (ii) digital recorders.


In the year 1974 B.C.C.L introduced a payroll system which used the computer concept.Subsequently the computerization was introduced for ledger,relative reports etc.In the year 1982 first computer was installed at Kalyan Bhawan from Calcutta for data processing.Till now the Headquarters of B.C.C.L has been centralized through networking.Each area of B.C.C.L  has its own EDP department of data processing.

COALNET  project for the networking of all areas with the B.C.C.L headquarters & networking  of all subsidiary of Coal India Limited & Ministry of coal is being worked out.Coalnet already networks many areas with the B.C.C.L  Headquarters & will very soon it will network the whole data processing of B.C.C.L.


  • Payroll system
  • House maintenance system
  • Daily attendance record system
  • LTC/LLTC system
  • Non-executive & executive information system
  • Online road sales system
  • Fund management system
  • Sales billing & dispatch accounting
  • Production information system
  • Financial accounting system
  • Coat & budget system
  • Patient registration at central hospital Dhanbad