Voltage regulator LM317 help - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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
Reply
 
Thread Tools Search this Thread
Old 6th January 2013, 01:42 PM   #1
ulle is offline ulle  Norway
diyAudio Member
 
Join Date: Dec 2010
Question Voltage regulator LM317 help

I have bought a low noise regulator as replacement for a standard LM317. I am not sure about the wiring and would really appreciate som help.
This is what I have measured on the LM317 that is assembled today:

Input - pin 1: 12v
Output - pin 2: 5v
Adjust - pin 3: 3.8v

As far as I understand I have to make some adjustment to the new regulator to feed the power correctly??

Very Low Noise 40?V Adjustable Voltage Regulator Board 3 Amp | eBay

  Reply With Quote
Old 6th January 2013, 01:54 PM   #2
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
You need to adjust the new regulator to 5 volts before fitting. The PDF shows a 10 K preset to set the voltage.

Fitting should be straightforward. I would remove the LM317 and the components that set the voltage on your existing reg.

You must confirm the voltage is correct before fitting. Get it wrong and it could well damage whatever you are powering.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 6th January 2013, 02:01 PM   #3
ulle is offline ulle  Norway
diyAudio Member
 
Join Date: Dec 2010
Quote:
Originally Posted by Mooly View Post
You need to adjust the new regulator to 5 volts before fitting. The PDF shows a 10 K preset to set the voltage.

Fitting should be straightforward. I would remove the LM317 and the components that set the voltage on your existing reg.

You must confirm the voltage is correct before fitting. Get it wrong and it could well damage whatever you are powering.
The new regulator is adjusted to 5V but I am not sure about the fitting when I look at the wiring diagram for the new regulator. The 317 is not grounded and how am I to get 3.8V from pin 3 of the the new regulator? Input and output is easy but nr.3?
  Reply With Quote
Old 6th January 2013, 05:14 PM   #4
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
You don't need the 3.8 volts. Thats a voltage generated by the original LM317 on its adjust pin. Look at the data sheet for the LM317 to help make it clearer,
http://www.datasheetcatalog.org/data...r/DS009063.PDF

I would call pin 1 the adjust pin and 3 the input. SO CHECK THAT DATA SHEET FIRST
Look at figure 1 and the pin outs on page 12

All good ?

1. You take the LM317 out.

2. I would then remove the voltage setting components that go to pin 1 on the LM317. Probably two resistors as in the data sheet, one going to the 5 volt line and one to ground.

3. Connect your new reg. Make sure the grounds are correct and that they really do go to a ground NEAR THE OLD REG. That's important. Look for small decoupling caps near the LM317 and use those points as ground.

4. Connect the new regulator input to pin and that the input goes to pin 3 (where you measured 12 volts) of the LM317 pads.

5. Connect the output of the new reg to pin 2 of the LM317 pads.

Job done
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 6th January 2013, 06:17 PM   #5
ulle is offline ulle  Norway
diyAudio Member
 
Join Date: Dec 2010
Quote:
Originally Posted by Mooly View Post
You don't need the 3.8 volts. Thats a voltage generated by the original LM317 on its adjust pin. Look at the data sheet for the LM317 to help make it clearer,
http://www.datasheetcatalog.org/data...r/DS009063.PDF

I would call pin 1 the adjust pin and 3 the input. SO CHECK THAT DATA SHEET FIRST
Look at figure 1 and the pin outs on page 12

All good ?

1. You take the LM317 out.

2. I would then remove the voltage setting components that go to pin 1 on the LM317. Probably two resistors as in the data sheet, one going to the 5 volt line and one to ground.

3. Connect your new reg. Make sure the grounds are correct and that they really do go to a ground NEAR THE OLD REG. That's important. Look for small decoupling caps near the LM317 and use those points as ground.

4. Connect the new regulator input to pin and that the input goes to pin 3 (where you measured 12 volts) of the LM317 pads.

5. Connect the output of the new reg to pin 2 of the LM317 pads.

Job done
Just great Well explained and understandable for a "no tech" like me. Thank you very much for support. Guys like you make DIY for ever so fun!
  Reply With Quote
Old 6th January 2013, 06:30 PM   #6
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Your welcome
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LM317 tracking pre-regulator and current regulator yagoolar Power Supplies 33 6th October 2012 12:36 PM
TIP50 + LM317 High Voltage Regulator bee696 Tubes / Valves 11 17th January 2010 04:23 PM
The simplistic Salas low voltage shunt regulator vs. LD1085/LM317 dvb projekt Power Supplies 20 5th January 2010 02:29 PM
LM317 Regulator Problem Bryan Tubes / Valves 12 2nd December 2005 07:37 PM
LM317 current regulator Bas Horneman Tubes / Valves 22 17th January 2003 10:25 PM


New To Site? Need Help?

All times are GMT. The time now is 02:19 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2