Power supply

Status
Not open for further replies.
A

adrianvon

Member
Hi all,

I am planning to build a power supply for a project that i am currently doing. The input will be connected to the mains (230VAC) and therefore a transformer is needed. I want to use the 7812 and 7805 as voltage regulators and i want the current to be 2A.

Does someone knows of a good tutorial for building such power supply with formulas used to determine the components used??

Thanks in advance.
Adrian
 

The 78XX series are not guaranteed to do 2A of load current.

I believe you want the LT1085 or LT1086 series devices.
 
Last edited:
Hi,

Thanks for the reply. I was planning to use pass transistors to increase the output current, but i will consider using the mentioned components.
 
adrianvon said:
Hi,

Thanks for the reply. I was planning to use pass transistors to increase the output current, but i will consider using the mentioned components.
Click to expand...
The problem with pass transistors is that they are not generally over-current or over-temperature protected as the regulator circuit is.
 
The problem with pass transistors is that they are not generally over-current or over-temperature protected as the regulator circuit is.
Click to expand...

Hi,

Thanks for that info. I will use the LT1085 or LT1086 instead of using pass transistor.

Does anyone know of a good tutorial to guide me on building a similar supply please? Or any formulas for determining the components values please (such as smoothing cap etc) ??

Thanks
 
Hi adrianvon,

The 7812 and 7805 are manufactured for an output current of 2A as well as for 1A.

The 2A regulators you need are 78S12 and 78S05.

Select a smoothing capacitor of 4,700uF at the input pins of the regulators. Also use 100nF caps from input to ground and from output to ground to avoid oscillations caused by sudden load changes.

Boncuk
 
Last edited:
Hi,

Thanks for your reply Boncuk . I will do some research on those transistors and on different types of transformers.
 
Status
Not open for further replies.

Similar threads

  • Question
Bench Power Supply
2
Replies
20
Views
2K
Tony Stewart
F
Handy Bench Power Supply
Replies
8
Views
2K
schmitt trigger
S
F
A Simple Power Supply Project
Replies
1
Views
1K
Tony Stewart
A
  • Question
13.56 mHz RF Power Supply
Replies
15
Views
3K
Tony Stewart
P
  • Question
power supply
2
Replies
32
Views
7K
Jverive
J
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…