Regulated PSU from Pedja

mlampret · 12th April 2006, 06:10 PM

I just need some help about capacitor polarity on Pedja's circuit. Since the lower rail is -24V I'm a little bit confused about placing the capacitors correctly. I wonder if it's ok on the picture I attached.

The picture was taken from Pedja's page and I added some + signs where they (hopefully) should go.

Thanks
-Marko

Igla · 12th April 2006, 06:39 PM

Hi Marko !
You forgot to attach the picture.If you are talking about LM338 circuit;
the positive side of the circuit: capacitor + side should be on +24V and cpacitor - side on ground;
the negative side of the circuit : capacitors + should go to ground and capacitor - side to -24V.

Regards;
Matjaž

mlampret · 12th April 2006, 07:15 PM

Obviously the picture wasn't attached.

I've placed the caps in the same way as you said. I was a bit confused because a friend suggested it was opposite.

Hvala

-Marko

Nordic · 13th April 2006, 07:25 AM

if you are still confused, the ones on the negative regulator is the wrong way around...

also unless I'm way stoned, you are connecting the -24 to the +24V's ground rail...

Greg Erskine · 13th April 2006, 07:38 AM

hi mlampret,

The schematic in the first post looks fine to me. Have a look here for a comparison.

http://www.tcaas.btinternet.co.uk/jlhnewps.htm

regards

Andypairo · 13th April 2006, 07:52 AM

Quote:

Originally posted by Nordic
if you are still confused, the ones on the negative regulator is the wrong way around...

also unless I'm way stoned, you are connecting the -24 to the +24V's ground rail...

The only way to use positive regulators for both rails is to make 2 +24V regulators and to connect them in series, as it is done in the schematic.
You have 0, +24 and +48V.
Now call the +24 your GND and you have a split power supply

Don't try this unless you have 2 separate secondaries and bridges.

Nordic please smoke less

Cheers

Andrea

mlampret · 13th April 2006, 09:53 AM

I'm glad that I still know how to connect the caps correctly

Thanks for your help, guys.

Nordic · 13th April 2006, 11:08 AM

looked totaly weird there for a second.....
but it makes sense now...

Igla · 13th April 2006, 01:30 PM

And you should put C3 and C4 directly to IC pins.

mlampret · 13th April 2006, 03:03 PM

Igla: you mean I should put C3 and C4 directly onto LM3886T pins?

I made the connections so that 2x4700uF caps, LM338, C3 and C4 and LM3886T are as close together as possible, while keeping the transformer away from the chips. And I'm planning to put the heatsinks between the transformer and the chips.

13th April 2006, 07:38 AM	#5
Greg Erskine diyAudio Member Join Date: Jan 2002 Location: Sydney/Australia	hi mlampret, The schematic in the first post looks fine to me. Have a look here for a comparison. http://www.tcaas.btinternet.co.uk/jlhnewps.htm regards __________________ Greg Erskine

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12th April 2006, 06:39 PM	#2
Igla diyAudio Member Join Date: Jun 2003 Location: Slovenia	Hi Marko ! You forgot to attach the picture.If you are talking about LM338 circuit; the positive side of the circuit: capacitor + side should be on +24V and cpacitor - side on ground; the negative side of the circuit : capacitors + should go to ground and capacitor - side to -24V. Regards; Matjaž

12th April 2006, 07:15 PM	#3
mlampret diyAudio Member Join Date: Apr 2006 Location: Tolmin	Obviously the picture wasn't attached. I've placed the caps in the same way as you said. I was a bit confused because a friend suggested it was opposite. Hvala -Marko

13th April 2006, 07:25 AM	#4
Nordic diyAudio Member Join Date: Sep 2005	if you are still confused, the ones on the negative regulator is the wrong way around... also unless I'm way stoned, you are connecting the -24 to the +24V's ground rail...

13th April 2006, 09:53 AM	#7
mlampret diyAudio Member Join Date: Apr 2006 Location: Tolmin	I'm glad that I still know how to connect the caps correctly Thanks for your help, guys.

13th April 2006, 11:08 AM	#8
Nordic diyAudio Member Join Date: Sep 2005	looked totaly weird there for a second..... but it makes sense now...

13th April 2006, 01:30 PM	#9
Igla diyAudio Member Join Date: Jun 2003 Location: Slovenia	And you should put C3 and C4 directly to IC pins.

13th April 2006, 03:03 PM	#10
mlampret diyAudio Member Join Date: Apr 2006 Location: Tolmin	Igla: you mean I should put C3 and C4 directly onto LM3886T pins? I made the connections so that 2x4700uF caps, LM338, C3 and C4 and LM3886T are as close together as possible, while keeping the transformer away from the chips. And I'm planning to put the heatsinks between the transformer and the chips.

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