Convert 21V to 15V dc to dc

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geminni

Member
2006-12-26 2:05 pm
I need a schematic to get 15V from 21V dc.
I know how to get that with LM7815 but with that I can have only 1A. I need something for 4Amps!
I need that for small power amplifier. I already have transformer with 15V secondary that gives mi 21V dc. Power IC's are rated at 15V so 21V will probably destroy them :)
 

FoMoCo

Member
2012-12-04 10:04 pm
I need a schematic to get 15V from 21V dc.
I know how to get that with LM7815 but with that I can have only 1A. I need something for 4Amps!
I need that for small power amplifier. I already have transformer with 15V secondary that gives mi 21V dc. Power IC's are rated at 15V so 21V will probably destroy them :)
Some of the older 7815 datasheets have a circuit that will allow you to "wrap around" a power transistor and get more current.
 
21V To 15V

I simulated a simple regulator with LT-spice.
 

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geminni

Member
2006-12-26 2:05 pm
I was not sure what was good for audio because some years ago I have made something with transistors but it was not good because it was bad for the sound so I did it with lm7815 and used it wisely! :D

Someone mentioned LM317 so I have found a schematics here:
24v to 12v converter | Power Supply Circuits
I did not used that much transistors of course :)

It worked fine under load of 3 amps so I just need to test it with amplifier and music.
 
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