Difference between step-up transformer and voltage amplifier

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Altec Peerless 4722 MC Step-up transformer
Altec Peerless 4722 MC Step-up transformer

Voltage amplifier? Similar or not?

A step up transformer basically increases the magnitude of primary applied voltage that is increases the amplitude of voltage wave form. A voltage amplifier does exactly the same.

Than a very strange but thinkable question comes what is the difference between the two and can we use a small step up transformer in place of voltage amplifier and vice-versa?


Transformers are unable to amplify (step up) an ac input Voltage without reducing (stepping down) it`s current capability.Amplifier can amplify both current and Voltage at the same time. We can have 1V at 1uA to drive the input but might also get many volts at many Amps at the output.
Transformer`s coil windings never requires a dc Voltage to operate. Sometimes a dc Voltage might be present in a transformer winding for auxiliaries but the dc is not required for the operation of the transformer.Amplifier almost always requires a dc working supply Voltage to operate.
Transformer has more winding added to its secondary winding to obtain Voltage amplification.An Amplifier actually modulates a fixed dc source Voltage in response to an ac input Voltage to obtain output Voltage amplification.
A transformer`s input current is proportional to its load current.Amplifier’s input current is normally almost independent of its load current.
A transformer is like a gearbox, whereas an amplifier is like an engine. The gearbox converts energy like a transformer.Amplifier is like an engine, which consumes fuel to give output. Similarly amplifier consumed DC supply to give output.
A step up transformer can amplify a specified type of input which is the sinusoidal input or time varying input and add to that the range of input the transformer is very flexible in range.Amplifier can amplify any signal and while the amplifier would have a limited range then in the saturation state.
In an ideal transformer output impedance is equal to the source impedance times the square of the turns ratio.An amplifier can have output impedance that is independent of the source impedance.

How amplifier works - The concept
How amplifier works - The concept

Transformer is not an amplifier, because:

The output and input powers are same and there is not any another source other than the signal (that is incoming AC voltage), Amplifier can amplify the signal voltage without reducing the output current.

Transformer follows the principle of induction where as Amplifier follows the principle of boosting the signal (voltage or current). Actually, the amplifier generates a completely new output signal based on the input signal. We can understand these signals as two separate circuits.

The output circuit is generated by the amplifier’s power supply, which draws energy from a battery or power outlet.

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About Author


Asif Eqbal

Asif Eqbal - Bachelor of Engineering in Electrical & Electronics engineering, from Manipal University, (Karnataka), India in 2006. Presently involved in the design of EHV outdoor substation and coal fired thermal power plants for more than seven years. Motto of joining EEP as a contributor is to share my little engineering experience and help the budding engineers in bridging the conspicuous gap between academics and Industrial practice. “If you have knowledge, let others light their candles with it, so that people who are genuinely interested in helping one another develop new capacities for action; it is about creating timeless learning processes".