Discussion in 'General Electronics Discussion' started by fuzailmomin, Feb 20, 2014.

1. ### fuzailmomin

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Feb 20, 2014
I want to find calculate all the values of resistors and output of transistors. input voltage is 230v ac 50 Hz. we want to find values of resistors and capacitors so please give formulas for find this values. the IC is LM 723 (Voltage Regulator). Thank you.

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2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Everything you need to know is here.

If you're planning to use one of these chips, I have to tell you that I first used it in about 1979 and it has been superseded by several generations since then.

3. ### fuzailmomin

6
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Feb 20, 2014
thanks for reply but i want to find the values of resistors and capacitors so please give me formulas for finding and i have that chip (lm723) .please help me.

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,267
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Jan 21, 2010
Why do you want to replicate this old and crusty design?

Do you realise that the link I gave you contains most of the information you need?

OK, one more thing -- there are emitter resistors. You'll probably want them to drop about 0.1V to 0.3V at maximum current. (so a value of 0.1 ohms is probably OK). And the power transistors will need significant heatsinking.

What are you planning to use for Q2 and Q3? 2N3055? You need to carefully consider the choice of transistors as the 723 is very easily destroyed by excessive current. It will happily destroy itself if you overload the regulator.

C1 is normally 1000uF per amp.

R8 just exists to discharge C1, so any reasonably high value is OK. 1k to 10k perhaps -- make sure you are a little generous with the power rating.

5. ### fuzailmomin

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Feb 20, 2014
thank you very much sir. I got it and all three transistors are 2n3055 and these circuit is our project for final year diploma in power electronics. And thanks for your reply. The link u send me is helpful to us. And if any doubt then i will contact u via this website. Thank you

6. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
If all three transistors are 2N3055 then I predict that you will have problems.

Be very sure that you do not exceed the maximum current or power dissipation for the 723. The 723 is not very forgiving in this regard.

7. ### fuzailmomin

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Feb 20, 2014
ok sir now what to do? can i put resistor across 723?.or any idea?

8. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
You need to study the specs of the 723 and determine what transistors are best to use.

I'm not going to do all of your homework.

9. ### fuzailmomin

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Feb 20, 2014
Ok sir thank you very much for helping me. And sorry for wasting your precious time.and i will find in all from refrence books. Thank you

10. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Don't try to be smart.

You have told me this is for a project. It's supposed to be your own work. How will it help you in the long term if I give you the answers? All it will mean is that you can't do the things that this project is supposed to demonstrate your ability to do. When you end up with a job you'll be lost.

Do the hard work now.

11. ### fuzailmomin

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Feb 20, 2014
ok sir . I m really very sorry. i understand and i will do hard work and i will find this by doing hard work and next time i nver do like this.i m really sorry.

12. ### rhaugen

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Feb 21, 2014
Well said Steve !

Ray