Magnetic Amplifier-final.pptx

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MAGNETIC AMPLIFIER

Submitted by:Dharmendra Chaurasia 1109131037

Contents  Introduction  History  Amplifier  Magnetic amplifier  Saturable reactor  Principal of magnetic amplifier  Working of magnetic amplifier  Application, strength & limitation  Uses in radio, aircraft & computing  Conclusion

INTRODUCTION 1.An electromagnetic device for amplifying electrical signal. 2. A magnetic amplifier uses the principle of transformers along with the concept of magnetic saturation of the core. 3.Does not require any moveable part. 4. The magnetic amplifier has certain advantages over :a)High efficiency b)Reliability c)Ruggedness

HISTORY 1. Developed as early as 1885 in united state. 2. At that time mainly used for electric machinery and theater lighting. 3. During world war II Germans used it in long range rockets to regulate frequency output of an a.c. generator. 4. Early time its uses as early development of voice transmission by radio.

Amplifier

1. An electronic amplifier is an electronic device that increases the power of a signal. 2. It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude. 3. An amplifier modulates the output of the power supply. 4. There are four basic types of electronic amplifier:a) Voltage amplifier  b)Current  amplifier c)Trans-conductance amplifier  

Magnetic amplifier

 The magnetic amplifier is an electromagnetic device for amplifying electrical signals.  The magnetic amplifier was invented early in the 20th century.  It was used as an alternative to vacuum tube amplifiers where robustness and high current capacity were required.  In World War-2 Germany used this type of amplifier, and it was used for instance in the V-2 rocket.  The magnetic amplifier was most prominent in power control and low-

The saturable reactor The saturable reactor is the device from which the magnetic amplifier has been fundamentally developed.  The three essential elements of saturable reactor are:

The saturable reactor (continued…)

Principal of magnetic amplifier 1. A mag-amp device may look like a transformer but the operating principle is quite different from a transformer essentially the mag-amp is a saturable reactor. 2. It makes use of magnetic saturation of the core. 3. For controlled saturation characteristics, the magnetic amplifier employs core materials which have a specific B-H curve shape that is highly rectangular, in contrast to the slowlytapering B-H curve of softly saturating core materials that are often used in normal transformers.

Working

1.The typical magnetic amplifier consists of two physically separate but similar transformer magnetic cores each of which has two windings - a control winding and an AC winding. 2. A small DC current from a low impedance source is fed into the series-connected control windings. The AC windings may be connected either in series or in parallel, the configurations resulting in different types of mag amps. 3.The amount of control current fed into the control winding sets the point in the AC winding waveform at which either core will saturate. In saturation, the AC winding on the saturated core will go from a high impedance state ("off") into a very low impedance state ("on") - that is, the control current controls at which voltage the mag amp switches "on".

The typical magnetic amplifier circuit shown above has the following components: 1.R1 - load resistance 2.G - gate winding 3.C - control winding 4.Ec - excitation 5.Es - input from AC source 6.Is - amplified AC current 7.Ic - control DC current

Application  As modulation and control amplifiers in the early development of voice transmission by radio.  As voice modulator and magnetic amplifiers were used in the keying circuits of large high-frequency alternators used for radio communications.  Magnetic amplifier is useful for control of lighting circuits, for stage lighting and for advertising signs.  Saturable reactor amplifiers were used for control of power to industrial furnaces.

Usage in computing

 Magnetic amplifiers were widely studied during the 1950s as a potential switching element for mainframe computers.  Mag amps could be used to sum several inputs in a single core, which was very useful in the arithmetic logic unit (ALU).  The mag amp was able to combine the advantages of tubes and transistors in an era when the latter were expensive and unreliable.

Strength  A static device with no moving parts.  Has a good tolerance to mechanical shock and vibration.  It requires no warm-up time.  Multiple isolated signals may be summed by additional control windings on the magnetic cores.  The magnetic amplifier is also used as a transducer in applications such as current measurement and the flux gate compass.

Limitations  The gain available from a single stage is limited and low compared to electronic amplifiers.  Solid-state amplifiers can be more compact and efficient than magnetic amplifiers.  The bias and feedback windings are not unilateral, and may couple energy back from the controlled circuit into the control circuit.  This complicates the design of multistage amplifiers when compared with electronic devices.

 Although, magnetic amplifier is an Conclusion outdated technology in present trend, It is the first device which can replace fragile vacuum tube in almost all its function.  It has good mechanical strength and maintenance free.

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