Supply Types

Let’s talk about what type of supply you can get easily first and then how to get something else from it.

The easiest way to get electrical supply is from your home outlet which is an Alternating Supply (or AC Supply).

The voltage you get is around 220Volts (In India) through which many of your electrical equipment’s work whether it could be a fan in your ceiling, Tube light or a Bulb.

While an alternating supply changes with time from a negative value to a positive value, there’s another kind of supply called DC or Direct Current Supply which has a constant voltage.

The best part is, not many, but, most of the electrical equipment’s these day’s work with DC supply including mobile phones, computers, LED’s, CFL’s, etc… i.e. the voltage at the terminals of equipment must remain constant with time.

Now the question is, how much amount of supply you need. Well, you can judge a supply by its voltage and the maximum amount of current it can deliver.

You can get the voltage and maximum current requirement as mentioned in the equipment itself.

Now the problem is to get a DC supply of required voltage from an AC supply of 220Volts, isn’t it?

Let’s take an example:

Your mobile phone must be charged as soon as its battery gets discharged, and for this purpose, we plug an adapter into it, while the other side of the adapter is plugged into the AC Socket.

So what does an adapter do exactly?

It converts the AC Supply in the socket into a DC Supply of certain voltage required for the mobile phone.

Thus, an Adapter is nothing but an AC to DC Converter.

Which means for all your applications which need dc supply, you just have to get the suitable adapter (AC to DC) whose rating matches your requirements.

Look upon the rating of a phone charger given:

Input: 240Volts AC

Output: 5Volts DC

The maximum current output of 550mA, which means it can supply a maximum current of 550 milliamps only.     

 Similarly, you can have a look at your mobile phone charger ratings or other adapters which might be connected in your Laptop, TV, etc...

Let’s take another example:

You have a CFL in your hand and you want to turn it on. What will you do? Simply, you would plug it in the bulb holder which also has an AC supply of 220Volts.

But as I said above, a CFL works on DC Supply, so how is that possible?

Well it has got an AC to DC converter build inside, which at first converts 220Volts AC voltage into a DC voltage suitable for the Bulb rod.

In the same way, most of the equipment has got AC to DC converter build inside.

A very simple AC to DC converter circuit is shown below:

Further, we will look at the ways to convert AC Voltage available in the home into a DC voltage of certain value.