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#1 |
diyAudio Member
Join Date: Mar 2007
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I need an adjustable voltage regulator like LM338 but LM338's datasheet confirms that maximum load is 35v. But i have 45v dc need to regulate about 34-36v.
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#2 |
diyAudio Member
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take a look at national semiconductor "Linear Brief 47" -- this will show you how to do it.
jack |
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#3 |
diyAudio Member
Join Date: Nov 2003
Location: England
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If you can make do with 700mA of current, you could go for the TL783... http://focus.ti.com/docs/prod/folders/print/tl783.html
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#4 |
diyAudio Member
Join Date: Mar 2007
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Thank you for reply. But i need to 5 amp regulator for using in regulated gainclone project.
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#5 |
diyAudio Moderator
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That amount of voltage drop and current in a regulator will likely dwarf the chip amp in complexity and heatsinking. Best use a different transformer, or look for a more suitable amp project. AAK's symasym version would work on those rails, and likely sound better than a chip amp anyway.
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#6 |
diyAudio Member
Join Date: Jun 2006
Location: North Californie
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Also, as eeka chu says above = take a look at page 10: http://focus.ti.com/lit/ds/symlink/tl783.pdf
High current and higher voltage (to 125 VDC), adjustable = no worry mate
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#7 |
diyAudio Member
Join Date: Apr 2007
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Consider using the LM317/LM337 regulators. They are available in both positive and negative polarities and are designed for floating applications. In other words, they can regulate any input voltage as long as the input to output voltage difference is less than aprox 35V. The output voltage is set by a ratio of two external resistors. I have used these devices in many applications, and they are reliable and easy to design with.
For a 5A supply, you will need to use an external pass transistor, but National Semi has an example shown in their application notes (look under LM317 or LM337 on their website). Hope this helps. JCM
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JCM |
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#8 |
diyAudio Member
Join Date: Jan 2005
Location: near london
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Hi
I have used lm devices with pass transistor as analogue guy says and I found it worked just fine. I used it for a JLH amplifier. Recently I prefer to simply use the pass transistor/mosfet with zeners to set the voltage without using the lm devices as I find this approach sounds the best. You can use either pass transistors or mosfets; either will work just fine. If you are not familiar with this concept there is a 4 page explanation of how to design and build a power supply using pass mosfets or transistors by Nelson Pass in the The Zen Variations part three "Active supply Regulation" at Passdiy. A superb article by Nelson as always and well worth a read if you have not done this before. I also add capacitors between the positive and negative rails and audio ground just before the amplifier modules. I do not know the details of your amplifiers but I usually use 1000uf capacitors in thsse locations. I also use high quality 105 degree capacitors. Don |
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#9 |
diyAudio Member
Join Date: Feb 2004
Location: Anonymityville
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I used LM317 and some 2N3055's to make a pass supply(with lots of help from friendly members).
http://www.diyaudio.com/forums/showt...03#post1046703 |
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#10 |
diyAudio Member
Join Date: Jun 2004
Location: Dorset, UK
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