Setting up power supply and using a multimeter:

Now after having an overview of breadboard let’s move forward to next step that is making a power supply on the board. Before starting let me tell you what is a power supply and why it is “a must to have” part of any circuit.

Power Supply: 

If you are familiar with the hardware of computer you probably had heard about its one of the many sections called as “Power supply”. Well if you are not familiar with it, it’s not a big deal. Every electronic gadget that you come across in your day to day life like mobile phones or computers or washing machine or television or any other gadget, they all consist of power supply unit. But here a question arises that “Why the heck we need a power supply??  Can’t we just start making some cool stuff directly?”  The answer to this question is simple, we know that all electronic circuits work on some power or electricity (Obviously we know that!). Now the circuits and projects we are going to make in upcoming blogs takes up 5v (volts). The supply is DC (Direct Current) in nature and the battery we are going to use is of 9 volts or may be more that means our circuit will either get ruined up or will not work according to our expectations (Yes this happens when dealing with IC’s etc). So the work or use of power supply unit is to convert this high voltage to the level, our circuit loves to work with.

Our power supply unit will have two main units an IC 7805 and capacitors. And why they are important in our circuit, read on…

7805 voltage regulator IC:

7805 integrated circuit is meant for converting a high input voltage to 5 volt output. The IC works in the range of 5 volts to 24 volts. As I explained before that we are going to use voltage source higher than that of circuit requirement, so in order to have voltage level of 5 volts we are using 7805 IC. The last two digits of his IC i.e. ‘05’ indicate the value of output voltage. The pin diagram is shown below. 

 

To count the legs, hold the IC such that its metal part is facing towards you. Now simply count from right to left. The pin at extreme right is pin number 1 input voltage supply i.e. our battery’s positive terminal will go here which can be of any value from 5 volts to 24 volts. The middle pin is the ground pin. The negative terminal of the battery or voltage source goes here and the left most pin i.e. pin number 3 is the output voltage which is 5 volt. These 5 volts are the needed voltage for our circuit and we will supply it throughout the breadboard

Capacitor:  

Components like IC’s etc create noise while working, well this is not noise in the form of sound but in the form of spikes that are created in a dc current.

 

These spikes seriously ruin the circuit. Moreover, when these spikes are generated by components, the power supplying unit is not able to adjust itself according to the brief period of change in voltage due to spikes. Hence to overcome this effect, a simple dielectric capacitor is used. The capacitors are capable of storing charge. They act as local energy storage in the circuit. These capacitors in a way, protects power supply from the circuit’s noise, they decouple both of them and hence these capacitors are also called as “Decoupling capacitors” These capacitors are capable to respond the instantaneous change in current. Hence they play a vital part in power supply unit.

For an instance you have came across the effect of decoupling capacitors. When you turn off your computer or television, you can see that after being plugged-off, the monitor takes time to turn off may be few seconds. This is the effect of capacitor. The time delay is due to the stored energy in capacitor and it takes time to discharge. As the capacitors get discharged, monitor turns off.

We will not be able to see this effect in our circuit because capacitor we are going to employ will have values in few micro farads they are capable of storing small charges as our power or voltage source is also small.

So, this was all about the theory part of power supply. Let’s begin making one.

Components you will require in making power supply are:

1.      IC 7805.

2.       Capacitor 10uF electrolytic type.

3.       Single core wire.

4.       Multimeter

5.       Battery/Power supply (must be 6 volts or up to 24 volts.)

6.       Wire stripper

7.       Enthusiasm/Will Power (well this is most important one!!)

I have linked some of the components to the Radio Shack if n your locals. (Except 8^thone…J )

If you are ready with you components, let’s start making it step by step:

Step 1)

Connect both source buses to each other so that our supply current can flow throughout the board. Remember that breadboard’s source buses are divided into two halves. There are ten blocks of buses. Among them first half i.e. five blocks of buses are connected to each other and then second half having rest five blocks are connected to each other. Refer to the figure below to clean up the mess.  Click here to know more on breadboard basics. We need to connect both these halves as shown in figure below.

Step 2):  

Now connect 7805 IC just like it is shown below. For the ease of understanding we are connecting it to the extreme left of the breadboard. After becoming a pro in breadboard connections you can connect the IC anywhere you want in the circuit. The IC is connected in our “component bus”.  Now our IC has settled down. It’s time to connect to the source bus with 7805. Well it is very simple. As I told you before, we want to flow 5 volt in our circuit and we also know that pin number three of IC 7805 gives out 5 volts. So we need to connect this pin number three with the source bus.

 

The source bus has two lines of holes. As you can see in above photo, the 5 volt output pin is connected to the lower line of source bus and the ground of IC 7805 is connected to the top line of source bus. The top bus is grounded so now it is termed as “Ground or gnd” and the lower one is connected to +5 volt supply so it is called as “VCC”.

Step 3): 

This step is similar to step 2. All you need to do is connecting the output and ground pin to the other half of the bread board as shown below. Now take out the multimeter and check out if connections are alright. To do so, cut out a small single core wire and insert it to the right most hole. Say you have connected it in VCC. Set the multimeter to diode mode. In this mode whenever the strobes of multimeter are touched together or to some conducting surface, a beep sound is produced. So, connect or touch one of the strobe of multimeter with the wire you have just connected temporarily at right most hole and touch the other strobe to the pin number three of the IC7805, if you hear a beep sound, your connections are alright and if not, then keep patience and check the connections again. In similar manner check for ground bus connection. Pull out the wire you just inserted in VCC and plug it into the ground bus and again check the connections by touching the strobes to the wire and the middle pin of 7805 IC. 

Do not forget to check the connections at both the source buses and for both VCC and gnd. This check through is very important and if not taken care off can result in messing up of whole circuit. The upcoming tutorials will have some seriously simple yet complex looking circuits and this check through will help you complete your circuit in single shot. (As it is very irritating when you discover that your circuit has some error…well computer programmers can understand this feelings…doesn’t matter how patience you have!).

Step 4):

  

Now comes the capacitor part. It is also very simple just connect the capacitors in both the source buses. Remember that capacitor is electrolytic in nature so pay careful attention towards the polarity of capacitors. To locate positive and negative terminals of capacitor, examine the capacitor’s body. You will see a thin strip stating ‘-’ (minus) sign. The lead below this strip is negative and of course another one is positive. Insert positive of electrolyte in VCC line and negative terminal in the ground line.

Refer to the photo below showing the implementation of capacitors.

Step 5):

That’s it, your power supply is now ready. It’s time to check out whether our board has 5 volts throughout the board or not. Connect the battery’s positive terminal to pin number 1 of the IC7805 and its negative terminal to the pin number 2 i.e. ground pin of 7805. This will initialize your IC and a steady output voltage of 5 volt is provided at pin number 3. Let’s verify this, to do so, set your multimeter to ’20 volts’. Now touch the negative strobe (mostly black one) to the middle pin i.e. ground terminal of IC7805 and positive terminal to the right most hole of the source bus as shown below. You will find the reading between 4.8 to 5.2 volts.

Watch out the video to have a clear view: