Adjustable regulator for 50v

Dengbej · 14th April 2007, 03:23 PM

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.

jackinnj · 14th April 2007, 03:40 PM

take a look at national semiconductor "Linear Brief 47" -- this will show you how to do it.

jack

eeka chu · 14th April 2007, 11:49 PM

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

Dengbej · 15th April 2007, 12:39 AM

Thank you for reply. But i need to 5 amp regulator for using in regulated gainclone project.

pinkmouse · 15th April 2007, 01:05 AM

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.

FastEddy · 15th April 2007, 01:22 AM

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

analog_guy · 19th April 2007, 05:52 AM

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

AMV8 · 19th April 2007, 12:51 PM

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

theAnonymous1 · 19th April 2007, 02:40 PM

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

Bone · 19th April 2007, 05:52 PM

Why not use the LM317HV see http://www.national.com/pf/LM/LM317HV.html

Tony.

14th April 2007, 03:23 PM	#1
Dengbej diyAudio Member Join Date: Mar 2007	Adjustable regulator for 50v 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.

15th April 2007, 01:05 AM	#5
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	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. __________________ Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?

15th April 2007, 01:22 AM	#6
FastEddy diyAudio Member Join Date: Jun 2006 Location: North Californie	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 __________________ Over compression is a problem with modern CD recordings [recent changes]

19th April 2007, 05:52 AM	#7
analog_guy diyAudio Member Join Date: Apr 2007	Adjustable Regulator 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 __________________ JCM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

14th April 2007, 03:40 PM	#2
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	take a look at national semiconductor "Linear Brief 47" -- this will show you how to do it. jack

14th April 2007, 11:49 PM	#3
eeka chu diyAudio Member Join Date: Nov 2003 Location: England	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

15th April 2007, 12:39 AM	#4
Dengbej diyAudio Member Join Date: Mar 2007	Thank you for reply. But i need to 5 amp regulator for using in regulated gainclone project.

19th April 2007, 12:51 PM	#8
AMV8 diyAudio Member Join Date: Jan 2005 Location: near london	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

19th April 2007, 02:40 PM	#9
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	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

19th April 2007, 05:52 PM	#10
Bone diyAudio Member Join Date: Jun 2004 Location: Dorset, UK	Why not use the LM317HV see http://www.national.com/pf/LM/LM317HV.html Tony.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Can someone tell me what this adjustable pot is for ?	WBFAir	Subwoofers	4	31st March 2007 03:32 AM
Monolithic Non-adjustable Regulator chips	pjpoes	Parts	2	22nd February 2007 08:29 PM
Active XO adjustable	Scribble	Multi-Way	9	7th August 2006 09:45 PM
Adjustable port	Mos Fetish	Multi-Way	2	27th June 2004 11:58 PM
Need adjustable LPF for sub...	JojoD818	Solid State	5	7th October 2003 07:55 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read