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Posts posted by Emiliano86
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hi ante,
The ripple appeared when I'd connected a load at maximun voltage that it gives (in my case 27V) and at 2.35 Amp, i know that it is very uncommon situation, it was only a test, ofcoures that without load it does'nt gives ripple.
The solution is to connect a higer voltage transformer, change the opamp, and improove the filter, like said audiogoru, instead of using a 24VAC trafo, a 30VAC one (or 16 + 16), but in that case the opamp MUST be changed by other with a higer volt range .
Good luck!!..
thanks audiogoru for your help!!!!....thank you ;) -
Pinky...i am planing to build this project, a regulated PSU with the LM317, i was searching on the net and i found a very similar regualtor the same voltage butinstead of 1.5 A, it can manage 3 A.......but bell I have some questions......for the LM317 PSU:
1 - if Iwant a 30VDC at maximun output, with 1.5A (very demandin), which is the transformer I need, because I have a 12 - 12 V 75VA?, or I have to use a 30 V one?...
2 - I am very intereting on the idea that you told at the beginig of the forum, that we can use a 12+12 transformer and a circuit to conect the 24V when i need more than 12.....but I can't find a circuit.... or something symilar, to have an idea.....Have you got a circuit or soemthing like that, or a croquis...???
3 - another question I have is about the ripple.....how can I improve the filter section in the ciruit to make better the ripple rejection?.....is a good idea use a choke input filter?......please help me...
4 - may be the LM317 could be replaced by the lm350K.......
Thank you very much!!!....and sorry for my bad english....... -
yes...but the problem is that it is imposible to find that OA in my country......I don't know what to do!!!!!!!......
I A M F R I E D!!! -
hi audiogoru!!......how are you?.....i am fighting with this PSU.....i could repair the current and voltage regualtor, i 've added two more 2n3055 transistors and it works fine.....it gives 3.25487 amps.....but the real bad thing apperared qhen i connected and test it in the osciloscope.........it was a desaster!!!!....the ripple is incredible!!!......and to get the thinsh wors it get to acsilate at maximun power 25VDC x 3.10amp......
I don't know .....
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YES AUDIOGORU.....AT FIRST I WORKS WHAT THE I PUT A BIG LOAD....THANK AUDIOGORU!!.. ;D
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Audiogoru, I have a problem, when I turn on the Power Supply the output is constant at 29,8 VDC.
My transformer is : 24 VAC - 75W
The DC Voltage at the base of 2N3055 is 32 VDC
I am using the TL081C OA
The voltage at pin 6 of U2 is 27 VDC
The voltage at the pin 3 of U2 is 9,3 VDC
I don't know what to do. When I disconect the 2N3055 th PSU get normaly.....
please help me!!!!!
thanks. -
thanks , MP ;D
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gonza.....why don't you try with the pcb pulicated on this web.....i used it and it worked!!!.......i'm doing some adjustments!.....but it works!!.....
(i'm from argentina too!!) -
audiogoru!!...i need your help....i built this PSU...and he led voltmeter with the 7107.....but when i connect it with that PSU..it turns off.....i think that it could be because :
1- I have a 70 VAC at the output when i have 30 VDC..
to make the dual polariti supply I took 24VAC from the transformer and I rectifier and filtered, and there i connected the two regalutaros with some resistors...
thanksss.... -
hello, my name is Emiliano, and I have a problem with this circuit:
"I've built the project -0 to 30 PSU-, and I decided to built this Voltmeter to conect it directly to the output from the PSU, but when i do that the Voltmeter turns off, I test the Voltmeter with another power and i worked.....I think that it could be because in te PSU project I have 70,02 V AC at max power (30,1 V DC)"...I don't know!!!......please if you can help me......
thankssss.........
LM317 Variable power supply
in Projects Q/A
Posted
hello...i have read all the comments adn i have some questions:
1- i want to design a pSU with 1.2-30V output at the maximun load possible, so what can i do to improve the ripple rejection?, more filter caps?
2- if the soulutio is to use more filer caps, i must use a bigger bridge, do not I?
3- if i use a 15 + 15 seconadary transformer, i can use only one side of it if i need a voltage in the ouput between 1.2 - 15V, and the two sides of the transformer if i need more than 15V, i think that it can improove the current output, but how can i do a voltage detector or selector or something like that?....
OK Thanks!!!!
:)