I want to build a 12v to 14v converter with LM2577T-Adj but i found 12v to 16v scheme diagram, any one can help what part i should chance to...?
in this scheme to make 12v to 14v output...?

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It's going to be more than one... Check the datasheet, it's relatively straight forward, just follow the formulas and don't skimp on the inductor.
http://www.national.com/ds/LM/LM1577.pdf


If you wanted to be EXTREMELY el-cheapo, you can add 3 silicon diodes to the output to drop it by approximately 2.1V This however will vary with the current being drawn and isn't recommended. If you don't care about proper regulation, then this is okay, otherwise do it properly....

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hi,
Reduce R1 [12k] to about 10.5K.
This is the Vsamp feedback to the switcher.

Look at the Vout formula [near the Vout terminal]

Vout = 1.23 * [1 + 10.5/1] = 1.23 * 11.5 = 14.14Vout.........OK?

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Have you checked that the appliance designed to run from 14V won't run off 12V?

The chances are you're wasting your time as you don't need a switching regulator.

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thanks to remind me about the Vout formula....but i don't find the 10.5 resistor so use 22k and 2k and the result in the tester 14.3....
thanks to every body for the help...........

 

How would you step-up from 12V to 14V without some kind of switching power supply? ;-)
S.

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LM2577 is a switching regulator/PS. Check the data sheet.

http://www.alldatasheet.com/datashee...SC/LM2577.html

John

 

The chances are the device will work from 12V so a 14V supply is not required so building one would be a total waste of time.

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I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

Hero may be right here. But if you still want to do this, go to National's website and run their WebBench software. You can design and simulate your circuit before building it. It will assist with all the parts values.

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You probably can't.

Hero was saying that if you don't really need 14V then you don't need to worry about generating it.