Rectifier

[ROOP]

can anyone explain the basic use of a transformer in a rectifier

[dalemiller]

can anyone explain the basic use of a transformer in a rectifier

Well, an assembly we might call a rectifier might get such a name because alternating current (AC) of known voltage is available near where some direct current (DC) is desired within a reasonable range of voltage. The transformer contributes a few things of practical importance: hopefully it adapts available ac voltage up or down to the voltage you wish it were, and it allows for DC isolation from the source of AC. It can be arranged to step voltage up or down for output AC voltages to as many outputs desired for the rectification circuitry. It is easy to overlook that it offers safety in that it can be arranged so as to prevent electric shock of creatures inadvertently connected between its output voltages and earth, chassis, or vehicular ground.

Edited October 2, 2010 by dalemiller

[ROOP]

yeah so can we make a rectifier without a transformer? suppose i have an ac source of 5v and want to make it to dc. so without the transfor i can right

[dalemiller]

yeah so can we make a rectifier without a transformer? suppose i have an ac source of 5v and want to make it to dc. so without the transfor i can right

Yes, but there might be a transformer in your circuit anyway, within your AC source. You will still have an AC component with your DC unless you have a filter and/or regulator. If you don't need smooth DC please disregard all that.

 

We could be more helpful if you mentioned what use you would have for the DC.

[Fredrick Boggs]

Rectifier transformer is converting AC energy into DC energy. But power transformer converting step up or step down AC energy without changing frequency. The purpose of the rectifier section is to convert the incoming AC from a transformer to other AC power source to some from of pulsating DC.

 

 

 

 

 

[Miles Guidon]

The answer to your question is "yes". If you have 5V AC, you can absolutely use a rectifier to get DC without a transformer. There is no need for a transformer at all.

 

I think the confusion is stemming from the fact that you do usually see a transformer before a rectifier, but only because that transformer is performing a "step-down" from a higher AC voltage to a lower AC voltage (both voltages are AC on either side of the trasnformer, before the rectifier), say from 120V AC to 30V AC. This 30V AC can then be rectified to give you a DC voltage.

 

The order without a transformer:

AC voltage --> rectifier --> DC voltage (with some ripple)

 

The order with a transformer:

AC voltage A --> transformer --> AC voltage B --> rectifier --> DC voltage (with some ripple) [A and B are the magnitudes of the AC voltages on either side of the transformer].