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12 volt\2amp switching power supply

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rozmad

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Hi Friends

I have a 12 V\2A power supply switching design need. Possible to design a simple circuit using UC3842 or transistor. Complete with transformer calculations and illustrations.
plz help
thank all
 

You should start with the datasheet of the UC3842 and read it thoroughly. Go through a few application notes. Check existing designs and then you can proceed. This way, you'll learn everything and can do all necessary calculations, etc, by yourself.

For information about flyback circuits and design using the UC3845, you can refer to Marty Brown's "Power Supply Cookbook". Also search different online forums, including edaboard.

You can then acquire enough information to build the power supply from scratch.

Hope this helps.
Tahmid.
 

I have a 12 V\2A power supply switching design need. Possible to design a simple circuit using UC3842 or transistor. Complete with transformer calculations and illustrations.
 

I have this. But in russian language )
 

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Hi all
i want to make this project also
but i have only tl494 ic on the market. i read its datasheet carefully and i understood most of it
i also read most of Marty Brown's "Power Supply Cookbook" chapter3.

now let me ask that i can not understand the voltage and current feedback in this datasheet pic
Pulse-Width-Modulated-Push-Pull-Converter-Circuit-Diagram.jpg
 

voltage and current feedback in this datasheet pic
Click to expand...
If voltage becomes less 0V on pin 15 (-0,24V on 1R Isense resistor) pulse width decreases and the same things occurs when voltage on pin 1 exceeds 5V.
 

thanks

i know that 1R resistor is used as a sense resistor to measure current and the 22k and 4.7k voltage divider circuit is for voltage feedback
but i can not understand the connection between the feedback PWM comparator input and the inverting inputs of the error amplifiers, this is my question.

thanks
 

connection between the feedback PWM comparator input and the inverting inputs of the error amplifiers
Click to expand...
If spend small time possible easy to find, for example, this - https://www.edaboard.com/threads/260421/
or else https://www.allaboutcircuits.com/vol_3/chpt_8/4.html and so on, and so forth ).

But there is particularity beside Tl494 in the manner of bad recharging of capacitor in feedback and also due to absence of the built-in compensations chains, so it happens to create puzzle ).
 
Last edited:

Check out this thread

Here

It goes through a step by step approach to Switch mode power supplies. The cookbooks is a great starting point. Its very good.

Like Tahmid suggests get the Power supply cookbook by Marty Brown, Its good.

Hope it helps
Cheers
K
 

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