Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

A Step up Transformer and a Voltage Amplifier

Status
Not open for further replies.

purifier

Full Member level 4
Joined
Nov 30, 2004
Messages
220
Helped
9
Reputation
18
Reaction score
8
Trophy points
1,298
Activity points
2,576
Can someone help me out please? I wanted to know the exact difference between a Step up transformer and a Voltage Amplifier?
 

purifier

Full Member level 4
Joined
Nov 30, 2004
Messages
220
Helped
9
Reputation
18
Reaction score
8
Trophy points
1,298
Activity points
2,576
I could get this for the transformer:

An electromagnetic device for changing the voltage of alternating current electricity. Every transformer has a primary coil and one or more secondary coils. The primary coil receives electrical energy from a power source and couples this energy to the secondary coils by means of a changing magnetic field. The energy appears as an electromagnetic force across the coil, and if a load is connected to the secondary the energy is transferred to the load. The voltage at which electric power is used in motors and lamps is less than that required for distribution. It is necessary to raise the voltage at the generating station to the value required for transmission, which is called "step up" the voltage. Then to lower it at the point of consumption to the values required by the motors and lamps, which is called "step down". The transformer is what makes these changes in voltage.

But what is the basic difference and in what circumstances do we use the Step Up Transformer and the Voltage Amplifier?
 

checkmate

Advanced Member level 3
Joined
Feb 25, 2004
Messages
833
Helped
178
Reputation
356
Reaction score
125
Trophy points
1,323
Location
Toilet Seat
Activity points
7,815
Op amps amplify voltages just like transformers. But it does not output a lot of current. A transofrmer on the other hand can transfer lots of power to the secondary coils. That is why an op amp is never used to drive motors or provide a power rail. If you read the datasheet, the max output current is usually less than 100mA.
 

IanP

Advanced Member level 5
Joined
Oct 5, 2004
Messages
7,942
Helped
2,307
Reputation
4,616
Reaction score
531
Trophy points
1,393
Location
West Coast
Activity points
66,459
Some other differences betwee a transformer and voltage amplifier:

Transformer from its nature isolates primary(s) from secondary(s). There are isolated amplifiers but they are not used very often.

Ideal transformer transfers the same amount of energy: what is comming in has to come out; input energy of an amplifier is low, and output(=input*gain) is higher.



PS: I woud not use the word "amplify" with transformers. Transformer doesn't amplify; it transfers or coverts energy...
 

Borber

Advanced Member level 5
Joined
Dec 31, 1999
Messages
1,602
Helped
234
Reputation
470
Reaction score
111
Trophy points
1,343
Location
on third flor
Activity points
11,862
Main difference between step up transformer and amplifier is that transformer is passive component and amplifier consists basically of active elements such as transistors, fets or tubes and passive components. Step up transformer "amplifies" the signal because secondary winding has more turns than primary. Ratio of secondary and primary voltages is proportional to ratio of turns in secondary and primary windings Vp/Vs=Np/Ns. Amplifiers exploit the property of active devices which convert small input power signal to higher output power signal by converting DC power from supply.
 

platonas

Full Member level 3
Joined
Aug 14, 2004
Messages
161
Helped
7
Reputation
14
Reaction score
1
Trophy points
1,298
Location
Universal Citizen
Activity points
1,977
Propably you mean as far as voltage output levels are concerned.
The step up transformer just rises the voltage according to the turns ratio. The power at the output is less than or equal (ideal transformer) to the power given at the input. That means I*V (input)=I*V (output) hence you have higher voltage but less current, hence it has a higher output impedance than that of input.

The voltage amplifier has simmillar characteristics but it could be of low output impedance (like the power amplifiers) so, it can have also a current amplification if it is designed so. The ratio of "Power input=Power output" does not apply here.
You can have 1V at 1uA to drive the input but you might get many volts at many Amps at the output.

Depending on the requirements of your design you may deside which one to use. Is up to the specific desinger and needs.
 

nand_gates

Advanced Member level 3
Joined
Jul 19, 2004
Messages
892
Helped
174
Reputation
348
Reaction score
51
Trophy points
1,308
Activity points
6,803
Let me summerize whatever is said above...

Transformer is a passive device hence no power gain like that of voltage
amplifier.
 

sefton

Member level 2
Joined
Dec 26, 2004
Messages
48
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,288
Activity points
524
IanP got it right, but let me put it like this: A transformer is like a gearbox, whereas an amplifier is like an engine. The gearbox converts energy like a tranformer. You can have high revs, low torque in (high voltage, low current) and low revs, high torque out (low voltage, high current). The engine creates rpm and torque, but consumes fuel, the same way that an amplifier needs a power supply.
 

usernam

Full Member level 5
Joined
Mar 9, 2004
Messages
268
Helped
18
Reputation
36
Reaction score
2
Trophy points
1,298
Activity points
2,081
Also a transformer involves the interaction of magnetic fields which is absent in voltage amplifiers.
 

maharshi_qis

Full Member level 5
Joined
Feb 14, 2007
Messages
241
Helped
13
Reputation
26
Reaction score
6
Trophy points
1,298
Activity points
2,462
a t/f is a device which will raise the primary volt to high value but the power would b const or generally alwz < primary power..
But amplifier is amplifies voltage by increasing power..
 

engr_najam

Full Member level 2
Joined
Aug 10, 2006
Messages
129
Helped
7
Reputation
14
Reaction score
1
Trophy points
1,298
Activity points
1,939
a step up voltage transformer can amplify voltage at the loss of current, while an amplifier can amplify current, a voltage or both
 

mr_anderson

Advanced Member level 4
Joined
Jan 23, 2007
Messages
100
Helped
5
Reputation
10
Reaction score
4
Trophy points
1,298
Activity points
2,005
a step up transfoer can amplify a specified type of input which is the sinusoidal input as i know and if u want to amplify another type of input i donot know but there are some limitations with very narrow duration pulses ( check out the pulse transformer ) while the amplifier can amplify any signal and add to that the range of input the transformer is very flexible in range while the amplifier would have a limited range then itz in the saturation state ,
 

Kral

Advanced Member level 4
Joined
Mar 28, 2005
Messages
1,326
Helped
280
Reputation
558
Reaction score
85
Trophy points
1,328
Location
USA
Activity points
13,417
purifier,
An amplifier can have an output impedance that is independent of the source impedance. A ideal transformer output impedance is equal to the source impedance times the square of the turns ratio.
.
For example, a transformer with a 1:100 voltage step-up (turns) ratio that is driven by an input with a source resistance of 1000 Ohms will have an output resistance of 1000 X (100^2) = 10,000,000 Ohms.
Regards,
Kral
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top