The TS needs to be sure to have @jayanthd write up the report for them and to get his contact info, too, so that a call can be made when the instructor asks anything not in the report.

@jayanthd: The rules of Homework Help prohibit doing a student's work for them, so your BOM has been deleted and so will any schematics you post. We are here to help steer them to solving their problems for themselves. Please act accordingly.

 

You really should have included this information in your first post. Just think of all of the posts recommending that you get wall-warts and such that could have been avoided. Also, knowing that you need to include both discrete components and IC's narrows the possibilities as well. Furthermore, the fact that you need to build and demonstrate the supply in the schematic narrows the field to supplies that are relatively easy to construct for someone new to electronics.

The next question is whether you want it to be adjustable between 9V and 12 V? If not and if a fixed-voltage supply is adequate, then pick one.

You also need to pick a current capacity. Is 3 A enough, or do you need 5 A?

With all of that in mind, and given that 3 to 5 amperes is a significant, but not outrageous, amount of current, I would recommend using a circuit based on either an LM317 adjustable voltage regulator or a LM7809/LM7812 fixed voltage regulator. To get that kind of current, use a circuit that uses a bypass transistor (which will check of the box of needing to use discrete components nicely, since it's possible that capacitors/resistors/diodes and the like are not what that requirement had in mind).

Look at the data sheets for the IC's I mentioned. They generally contain several power supply circuits and sometimes decent explanations of how they work.

Thanks you,
Fixed 12v 3 amperes output is okay for me.
Thats what Im searching of how to get a 3 amperes output,
Can you recommend me for the current booster transistor and how it connects to the circuit.

 

@iamprincejoy: I would strongly recommend against just having someone provide you with a schematic and parts list, unless your goal is to learn little to nothing and possibly get a failing grade when you aren't able to adequately explain how your supply works, since that appears to be a key element of this assignment.

Wouldn't it be better if you could describe exactly what each component in your design does and how it does it and why that component was chosen?

Thank you for that sir, I appreciated.

 

Thank you for that sir, I appreciated.

@Mods

But can I explain the circuit here ?

All you need is a 220V to 12V step down transformer. You need a 6A or 8A bridge rectifier at the secondary side of the transformer to build a bridge rectifier power supply.

12V * 1.4142 = 16.9704V

In bridge rectifier there will be two diode drops (refer datasheet of bridge rectifier for drop voltage)

assuming 0.7V drop per diode total drop = 1.4V

16.9704 - 1.4 = 15.57V is what you get at the output of the bridge rectifier after filtering it qith a 1000 uF 63V (63V because you will be using LM2576 Buck regulator to get 12V 3A output)

Buck regulator is used because power loss will be less. If you use standard LDO type regulators then if difference between input and output voltages are large then large voltage has to be dropped by the regulator and power loss will be high and you will be needeing a good heatsink for the regulator.

You still need a heatsink for LM2576HV-12

HV version of the regulator I chose because you can input max 60V into the regulator.

Refer to LM2576-5.0 or LM2576-12 datasheet and you will have the regulator circuit.

You can use a 1k resistor and Green Led (2.1V Vf) and make a indicator at the output of the power supply.

You will be also needing two terminal blocks, one at the input of transformer and one at the output of the power supply.

For making indicator calculation is

R = (V - VLed) / ILed

R = (12V - 2.1V) / 10mA = 990 Ohms.

You can use 1k which is a standars value resistor.

2.1V is Led Vf

12V is regulator output.

 

Decide and tell if you want LDO type regulator based power supply or Switching Buck Regulator type power supply.

http://www.electronics-tutorials.ws/blog/variable-voltage-power-supply.html

 

@Mods

But can I explain the circuit here ?

All you need is a 220V to 12V step down transformer. You need a 6A or 8A bridge rectifier at the secondary side of the transformer to build a bridge rectifier power supply.

12V * 1.4142 = 16.9704V

In bridge rectifier there will be two diode drops (refer datasheet of bridge rectifier for drop voltage)

assuming 0.7V drop per diode total drop = 1.4V

16.9704 - 1.4 = 15.57V is what you get at the output of the bridge rectifier after filtering it qith a 1000 uF 63V (63V because you will be using LM2576 Buck regulator to get 12V 3A output)

Buck regulator is used because power loss will be less. If you use standard LDO type regulators then if difference between input and output voltages are large then large voltage has to be dropped by the regulator and power loss will be high and you will be needeing a good heatsink for the regulator.

You still need a heatsink for LM2576HV-12

HV version of the regulator I chose because you can input max 60V into the regulator.

Refer to LM2576-5.0 or LM2576-12 datasheet and you will have the regulator circuit.

You can use a 1k resistor and Green Led (2.1V Vf) and make a indicator at the output of the power supply.

You will be also needing two terminal blocks, one at the input of transformer and one at the output of the power supply.

For making indicator calculation is

R = (V - VLed) / ILed

R = (12V - 2.1V) / 10mA = 990 Ohms.

You can use 1k which is a standars value resistor.

2.1V is Led Vf

12V is regulator output.

Thanks sir.
I need a circuit first so that if it is approve by my professor and thats the time I will build the circuit.

 

Thanks sir.
I need a circuit first so that if it is approve by my professor and thats the time I will build the circuit.

Don't you want the explanation of the working of the circuit I provide. How will you explain the working to your professor ?

Mods said that if I post circuit then they will delete it because it is your homework. Maybe you have disabled PMing. Send a PM to me and I will reply to it with a circuit.

Or email me at Okada2019@gmail.com

and I will provide you the circuit if providing circuit in forum or through PM is not allowed or against the rule of the forum for homework work.

 

Don't you want the explanation of the working of the circuit I provide. How will you explain the working to your professor ?

Mods said that if I post circuit then they will delete it because it is your homework. Maybe you have disabled PMing. Send a PM to me and I will reply to it with a circuit.

Or email me at Okada2019@gmail.com

and I will provide you the circuit if providing circuit in forum or through PM is not allowed or against the rule of the forum for homework work.

I already send a message to you sir. Thank you

 

Hello,

@jayanthd , Did you see post #2 of the forum rules for the Home Work Help forum?
https://forum.allaboutcircuits.com/...-in-the-homework-help-forum.3002/#post-357336

Do not provide complete solutions here via email or PM !!

@iamprincejoy , As this is your homework project, you will have to show us what you have done to solve your problem.
From there we can discuss improvements and give suggestions for the project.

Bertus

 

@bertus

OP has not mentioned whether she is High School student or engineering student.

If OP is a high school student then we need to help her with a simple and good circuit as his/her's professor requires.

I prefer LT1083-12 based 12V 3A power supply as OP need fixed 12V 3A power supply.

 

OP has not mentioned whether she is High School student or engineering student.

Professors typically teach at the collegiate level. If the OP is not an engineering student, why did the professor ask them to design a power supply?

If OP is a high school student then we need to help her with a simple and good circuit as his/her's professor requires.

There is a world of difference between HELP and do. You can provide references for them to read to guide them. You can answer their specific questions about a circuit. You can ask them to provide a block diagram and the functional description of each block. You could have provided the block diagram with generic function descriptions to kick start their thinking. I for one would have defended you if you took that action. There simply isn't too many people using block diagrams these days because functionality can be a single chip and in some cases the whole unit.

If your going to do their thinking for them, well, that would be against the rules of the homework or any other related course work.

Do what you want offline. No one can stop you. The TS ultimately bears the responsibility for work they can not explain, whether it's the current circuit or future work should you continue to design for them.

 

Professors typically teach at the collegiate level. If the OP is not an engineering student, why did the professor ask them to design a power supply?



There is a world of difference between HELP and do. You can provide references for them to read to guide them. You can answer their specific questions about a circuit. You can ask them to provide a block diagram and the functional description of each block. You could have provided the block diagram with generic function descriptions to kick start their thinking. I for one would have defended you if you took that action. There simply isn't too many people using block diagrams these days because functionality can be a single chip and in some cases the whole unit.

If your going to do their thinking for them, well, that would be against the rules of the homework or any other related course work.

Do what you want offline. No one can stop you. The TS ultimately bear the responsibility for work they can not explain, whether it's the current circuit or future work should you continue to design for them.

Ok. I got the point.

 

Here's something for the TS to read ... and @WBahn alluded to it in his earlier post. Did the TS search for any documentation based on WBahn's suggestion?

 

Hello,

@JoeJester , Did you see the info I gave in post #8?

Bertus

 

This will be fine as OP wants 12V 3A PSU.

www.ti.com/lit/ds/symlink/lm350a.pdf

 

Hello,

@JoeJester , Did you see the info I gave in post #8?

Bertus

Yes I did, however, I didn't visit the link until now. It was a very nice page and should have satisfied the TS's initial inquiry and provided more questions to the forum from the TS.

Yes, I should have read it earlier, and yes, you should get the credit for providing the right assistance.

 

LM338K will be better. If professor puts 3A load then LM350 (if used) will be running at max load current. It may file even though datasheet tells guaranteed 3A output.

So, LM338K will do. Just two resistors are needed to fix the output voltage to 12V.

Refer LM338K datasheet and make your circuit.

 

Thanks you,
Fixed 12v 3 amperes output is okay for me.
Thats what Im searching of how to get a 3 amperes output,
Can you recommend me for the current booster transistor and how it connects to the circuit.

You really need to be developing the ability to research information instead of just asking others to hand it to you.

You live in an age of easy access to literally a whole world of information at your fingertips.

http://bfy.tw/DO6Q

There are several useful links there, at least in the search results I got.

The first one: https://people.eecs.ku.edu/~callen58/501/LinearRegulators.pdf has some good foundational information but goes off in a direction that I don't think is really right for you.

The one from UNC Charlotte (uncc.edu) is a lot closer to where I think you are at the moment.