voltage regulators

odysseybmx414 · 29th December 2005, 02:33 PM

ok i dont know much about regulated psu's except that they "regulate"
i have a transformer and after rectification puts out +-45VDC i want to bring this down to <80V total. i tried using diodes to lose a few volts (2 per rail) but still +-45VDC. my question is what regulators would be the best to use for such a voltage and to use on a couple OPA541 chips??

mateo88 · 29th December 2005, 06:28 PM

The simplest would be lm338's.

moutoulos · 29th December 2005, 07:43 PM

Οr... like this ...

Wombat2 · 30th December 2005, 04:49 AM

Lets give credit to Rod Elliottt for the above schematic for his pre reg P102

rodolfo · 30th December 2005, 05:47 AM

Quote:

Originally posted by moutoulos
�r... like this ...

r5 10(omegas) ?????
sorry

the eshe.... is ok....only resistor value ????

Keld · 30th December 2005, 05:53 AM

Quote:

Originally posted by rodolfo

r5 10(omegas) ?????
sorry
the eshe.... is ok....only resistor value ????

?????????????

Read more here: http://sound.westhost.com/project102.htm

boholm · 30th December 2005, 06:36 AM

Quote:

Originally posted by odysseybmx414
i tried using diodes to lose a few volts (2 per rail) but still +-45VDC.

I take it you did not put a load on it? There have to run a current thru' the diodes, before they come with the 0.7 volts. So try and put a load on it and see what happens. 10K 1 W should do it for testing.

lineup · 30th December 2005, 08:05 AM

Is this a possible 4 transistor regulator?

Best if average input voltage is:
1.10 x (Vout + 2)
to account of eventual mains AC 10% drop.

For negative supply transistors are mirrored, NPN to PNP and PNP to NPN.
I have difficult to find out values.
Especially capacitors values.
Values are also much dependent of max output current and amount of ripple at input voltage.

AndrewT · 30th December 2005, 08:26 AM

Hi,
the +-45Vdc is when you have open circuit load.

What is the minimum draw when the circuit is connected?

The open circuit voltage will drop as the load increases and may fall just far enough to lie within the range required. Then your diode drops can be used for final adjustment.

odysseybmx414 · 30th December 2005, 02:51 PM

i connected psu to a opa541 2 channel amp ( one per ch. ) and the voltage dropped to +-41V still too much i played to loud volume and the least voltage i got was +-40V i dont want to take chances on blowing my chips.are you sure the 338's will handle the voltage?

29th December 2005, 02:33 PM	#1
odysseybmx414 diyAudio Member Join Date: Feb 2005 Location: Watertown, NY	voltage regulators ok i dont know much about regulated psu's except that they "regulate" i have a transformer and after rectification puts out +-45VDC i want to bring this down to <80V total. i tried using diodes to lose a few volts (2 per rail) but still +-45VDC. my question is what regulators would be the best to use for such a voltage and to use on a couple OPA541 chips??

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29th December 2005, 06:28 PM	#2
mateo88 diyAudio Member Join Date: May 2004 Location: Argyle, Texas	The simplest would be lm338's.

30th December 2005, 04:49 AM	#4
Wombat2 diyAudio Member Join Date: Nov 2003 Location: Brisbane	Lets give credit to Rod Elliottt for the above schematic for his pre reg P102

30th December 2005, 08:26 AM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the +-45Vdc is when you have open circuit load. What is the minimum draw when the circuit is connected? The open circuit voltage will drop as the load increases and may fall just far enough to lie within the range required. Then your diode drops can be used for final adjustment.

30th December 2005, 02:51 PM	#10
odysseybmx414 diyAudio Member Join Date: Feb 2005 Location: Watertown, NY	i connected psu to a opa541 2 channel amp ( one per ch. ) and the voltage dropped to +-41V still too much i played to loud volume and the least voltage i got was +-40V i dont want to take chances on blowing my chips.are you sure the 338's will handle the voltage?