Electronic assignment help

Building the Regulator

To build the regulator, you need three parts:

· A 7805 5-volt voltage regulator in a TO-220 case (Radio Shack part number 276-1770)

· Two electrolytic capacitors, anywhere between 100 and 1,000 microfarads (typical Radio Shack part number 272-958)

The 7805 takes in a voltage between 7 and 30 volts and regulates it down to exactly 5 volts. The first capacitor takes out any ripple coming from the transformer so that the 7805 is receiving a smooth input voltage, and the second capacitor acts as a load balancer to ensure consistent output from the 7805.

The three leads are, from left to right, input voltage (7 to 30 volts), ground and output voltage (5 volts).

The 7805 has three leads. If you look at the 7805 from the front (the side with printing on it), the three leads are, from left to right, input voltage (7 to 30 volts), ground, and output voltage (5 volts).

To connect the regulator to the transformer, you can use this configuration.

The two capacitors are represented by parallel lines. The "+" sign indicates that electrolytic capacitors are polarized: There is a positive and a negative terminal on an electrolytic capacitor (one of which will be marked). You need to make sure you get the polarity right when you install the capacitor.

You can build this regulator on your breadboard. To do this, you need to understand how a breadboard is internally wired.

On the outer edges of the breadboard are two lines of terminals running the length of the board. All of these terminals are internally connected. Typically, you run +5 volts down one of them and ground down the other. Down the center of the board is a channel. On either side of the channel are sets of five interconnected terminals. You can use your volt-ohm meter to see the interconnections. Set the meter's dial to its ohm setting, and then stick wires at different points in the breadboard (the test leads for the meter are likely too thick to fit in the breadboard's holes).

In the ohm setting, the meter measures resistance. Resistance will be zero if there is a connection between two points (touch the leads together to see this), and infinite if there is no connection (hold the leads apart to see this). You will find that points on the board really are interconnected as shown in the diagram. Another way to see the connections is to pull back the sticker on the back of the breadboard a bit and see the metal connectors.

Now connect the parts for your regulator:

1. Connect the ground wire of the transformer to one of the long outer strips on the breadboard.

2. Plug the 7805 into three of the five-hole rows.

3. Connect ground from the terminal strip to the middle lead of the 7805 with a wire -- simply cut a short piece of wire, strip off both ends and plug them in.

4. Connect the positive wire from the transformer to the left lead (input) of the 7805.

5. Connect a capacitor from the left lead of the 7805 to ground, paying attention to the polarity.

6. Connect the 5-volt lead of 7805 to the other long outer terminal strip on the breadboard.

7. Connect the second capacitor between the 5-volt and ground strips.

You have created your regulator. It might look like this when you are done (two views):

In both of the figures, the lines from the transformer come in from the left. You can see the ground line of the transformer connected directly into the ground strip running the length of the board at the bottom. The top strip supplies +5 volts and is connected directly to the +5 pin of the 7805. The left capacitor filters the transformer voltage, while the right capacitor filters the +5 volts produced by the 7805. The LED connects between the +5 and ground strips, through the resistor, and lets you know when the power supply is "on."

Plug in the transformer and measure the input and output voltage of the 7805. You should see exactly 5 volts coming out of the 7805, and whatever voltage your transformer delivers going in. If you do not, then immediately disconnect the transformer and do the following:

· Pull out the capacitors. Plug the transformer back in for a moment and see if that changed anything.

· Make sure the ground wire and positive wire from the transformer are not reversed (if they are, it is likely the 7805 is very hot, and possibly fried).

· Make sure the transformer is producing any voltage at all by disconnecting it and checking it with your volt meter. See the previous page to learn how to do this.

Once you see 5 volts coming out of the regulator, you can test it further and see that it is on by connecting an LED to it. You need to connect an LED and a resistor in series -- something that is easy to do on your breadboard. You must use the resistor or the LED will burn out immediately. A good value for the resistor is 330 ohms, although anything between 200 and 500 ohms will work fine. LEDs, being diodes, have a polarity, so if your LED does not light, try reversing the leads and see if that helps.

It might seem like we've had to go to a tremendous amount of trouble just to get the power supply wired up and working. But you've learned a couple of things in the process. Now we can experiment with Boolean gates!

http://www.electronicshub.org/understanding-7805-ic-voltage-regulator/

A regulated power supply is very much essential for several electronic devices due to the semiconductor material employed in them have a fixed rate of current as well as voltage. The device may get damaged if there is any deviation from the fixed rate. The AC power supply gets converted into constant DC by this circuit. By the help of a voltage regulator DC, unregulated output will be fixed to a constant voltage. The circuit is made up of linear voltage regulator 7805 along with capacitors and resistors with bridge rectifier made up from diodes. From giving an unchanging voltage supply to building confident that output reaches uninterrupted to the appliance, the diodes along with capacitors handle elevated efficient signal conveyal.

Description:

As we have previously talked about that regulated power supply is a device that mechanized on DC voltages and also it can uphold its output accurately at a fixed voltage all the time  although if there is a significant alteration in the DC input voltage.

ICs regulator is mainly used in the circuit to maintain the exact voltage which is followed by the power supply. A regulator is mainly employed with the capacitor connected in parallel to the input terminal and the output terminal of the IC regulator. For the checking of gigantic alterations in the input as well as in the output filter, capacitors are used. While the bypass capacitors are used to check the small period spikes on the input and output level. Bypass capacitors are mainly of small values that are used to bypass the small period pulses straightly into the Earth.

A circuit diagram having regulator IC and all the above discussed components arrangement revealed in the figure below.

Regulated Power Supply Circuit – ElectronicsHub.Org

The working of the components coupled in the circuit above is revealed in the following table:

Component	Function
C1	This capacitor is known as bypass capacitor and is employed to bypass extremely tiny duration spikes to the ground with no distress the other components.
C2	C2 is the filter capacitor employed to steady the slow changes in the voltage applied at the input of the circuit. Escalating the value of the capacitor amplify the stabilization as well as the declining value of the capacitor reduces the stabilization. Moreover this capacitor is not alone capable to ensure very constricted period spikes emerge at the input.
C3	C3 is known as a filter capacitor employed in the circuit to steady the slow alterations in the output voltage. Raising the value of the capacitor enlarges the stabilization furthermore declining the value of the capacitor declined the stabilization. Moreover this capacitor is not alone capable to ensure very fine duration spikes happen at the output.
C4	C4 is known as bypass capacitor and worked to bypass very small period spikes to the earth with no influence the other components.
U1	U1 is the IC with positive DC and it upholds the output voltage steady exactly at a constant value even although there are major deviation in the input voltage.

As we have made the whole circuit till now to be operated on the 5V DC supply, so we have to use an IC regulator for 5V DC. And the most generally used IC regulators get into the market for 5V DC regulation use is 7805. So we are connecting the similar IC in the circuit as U1.

IC 7805 is a DC regulated IC of 5V. This IC is very flexible and is widely employed in all types of circuit like a voltage regulator. It is a three terminal device and mainly called input , output and ground. Pin diagram of the IC 7805 is shown in the diagram below.

Pin Diagram of IC 7805 – ElectronicsHub.Org

 The pin explanation of the 7805 is described in the following table:

PIN NO.	PIN	DESCRIPTION
1	INPUT	In this pin of the IC positive unregulated voltage is given in regulation.
2	GROUND	In this pin where the ground is given. This pin is neutral for equally the input and output.
3	OUTPUT	The output of the regulated 5V volt is taken out at this pin of the IC regulator.

In the circuit diagram C2 as well as C3 are filter capacitor while bypass capacitors are the C1 and C4.The electrolytic polarized capacitors are employed for this purpose. For the purpose of filter capacitors normally 10mfd value of the capacitor used. And in these projects we also used 100mfd value of the capacitor. While in all kinds of circuit the value of bypass capacitor is 0.1 mfd. And in generally un-polarized mainly disc capacitors employed for this purpose.

Currently we have the circuit for the 5V DC positive regulation and we are also familiar with the component values used in the circuit. In the table below we have mentioned the value in detail of all the components used in the circuit of 5V DC positive regulator.

SNO	COMPONENT	TYPE	VALUE
1	C1	CAPACITOR	0.1 mfd
2	C2	CAPACITOR	1000 mfd
3	C3	CAPACITOR	1000 mfd
4	C4	CAPACITOR	0.1 mfd
5	U1	POSITIVE DC REGULATOR	7805

Example of 7805 Regulator:

How to Get Constant DC Power Supply from AC?

7805 Voltage Regulator Circuit Diagram – ElectronicsHub.Org

Also read the related post: Variable Voltage  Power Supply from Fixed Voltage Regulator

The output generated from the unregulated DC output is susceptible to the fluctuations of the input signal.IC voltage regulator  is connected with bridge rectifier in series in these project so to steady the DC output against the variations in the input DC voltage.To obtain a stable output of 5V, IC 7805 is attached with 6-0-6V along with 500mA step down transformer as well as with rectifier.To suppress the oscillation which might generate in the regulator IC, C2 capacitor of 0.1 uF value is used. When the power supply  filter  is far away from the regulated IC capacitor C2 is used.Ripple rejection in the regulator is been improved by C4 capacitor(35uf) by avoiding the ripple voltage to be amplified at the regulator output.The output voltage is strengthen and deduction of the output voltage is done capacitor C3(0.1uF). To avoid the chance of the input get shorted D5 diode is used to save the regulator. If D5 is not presented in the circuit, the output capacitor can leave its charge  immediately during low impedance course inside  the regulators.

http://www.analog.com/static/imported-files/pwr_mgmt/PM_vr_design_08451a.pdf

General Design Fundamentals

A voltage regulator generates a fixed output voltage of a preset magnitude that remains constant regardless of changes to its input voltage or load conditions. There are two types of voltage regulators: linear and switching.

A switching regulator converts the dc input voltage to a switched voltage applied to a power MOSFET or BJT switch. The filtered power switch output voltage is fed back to a circuit that controls the power switch on and off times so that the output voltage remains constant regardless of input voltage or load current changes.

What are some of the switching regulator topologies?

There are three common topologies: buck (step-down), boost (step-up) and buck-boost(step-up/stepdown). Other topologies include the flyback, SEPIC, Cuk, push-pull, forward, full-bridge, and half-bridge topologies.

How does switching frequency impact regulator designs?

Higher switching frequencies mean the voltage regulator can use smaller inductors and capacitors. It also means higher switching losses and greater noise in the circuit.

What losses occur with the switching regulator?

Losses occur as a result of the power needed to turn the MOSFET on and off, which are associated with the MOSFET’s gate driver. Also, MOSFET power losses occur because it takes a finite time to switch to/from the conduction to non-conduction states. Losses are also due to the energy needed to charge and discharge the capacitance of the MOSFET gate between the threshold voltage and gate voltage.

http://www.rakeshmondal.info/IC-7805-Voltage-Regulator

IC 7805 voltage Regulator

Voltage regulator IC's are the IC’s that are used to regulate voltage.

IC 7805 is a 5V Voltage Regulator that restricts the voltage output to 5V and draws 5V regulated power supply. It comes with provision to add heatsink.

The maximum value for input to the voltage regulator is 35V. It can provide a constant steady voltage flow of 5V for higher voltage input till the threshold limit of 35V. If the voltage is near to 7.5V then it does not produce any heat and hence no need for heatsink. If the voltage input is more, then excess electricity is liberated as heat from 7805.

It regulates a steady output of 5V if the input voltage is in rage of 7.2V to 35V. Hence to avoid power loss try to maintain the input to 7.2V. In some circuitry voltage fluctuation is fatal (for e.g. Microcontroller), for such situation to ensure constant voltage IC 7805 Voltage Regulator is used. For more information on specifications of 7805 Voltage Regulator please refer the data sheet here (IC 7805 Voltage Regulator Data Sheet).

IC 7805 is a series of 78XX voltage regulators. It’s a standard, from the name the last two digits 05 denotes the amount of voltage that it regulates. Hence a 7805 would regulate 5v and 7806 would regulate 6V and so on.

The schematic given below shows how to use a 7805 IC, there are 3 pins in IC 7805, pin 1 takes the input voltage and pin 3 produces the output voltage. The GND of both input and out are given to pin 2.

 

Save this picture for reference.

 

7805 VOLTAGE REGULATOR IC CIRCUIT

 

 

Introduction to voltage regulator | Description voltage regulator:-

Voltage Regulator is one of the most important and commonly used electrical components. Voltage Regulators are responsible for maintaining a steady voltage across an Electronic system. Voltage fluctuations may result in undesirable effect on an electronic system, so to maintaining a steady constant voltage is necessary according to the voltage requirement of a system.

Let us assume a condition when a simple light emitting diode can take a max of 3V to the max, what happens if the voltage input exceeds 3V ?, ofcourse the diode will burn out. This is also common with all electronic components like, led’s, capacitors, diodes etc. The slightest increase in voltage may result in the failure of entire system by damaging the other components too. For avoiding Damage in such situations voltage regulator are used for regulated power supply.