V regulation for digital circuits - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

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 27th March 2008, 02:05 AM   #1
diyAudio Member
 
DECKY999's Avatar
 
Join Date: Jul 2007
Default V regulation for digital circuits

I know there were endless posts on these pages regarding usfulness of super (descrete) regulators in digital circuits and their possible advantages over standrad LM78xx chips.

I know that good old 78xx are not made for audio but how about using some more modern regulators.

What are people opinions on lets say LM2940 or LM1086. Or is there any other better alternative for regulating digital 5V supply that does not cost 30euro a piece?
  Reply With Quote
Old 27th March 2008, 11:05 PM   #2
rossl is offline rossl  United States
diyAudio Member
 
rossl's Avatar
 
Join Date: Nov 2004
Location: Central Ohio
You can use 78xx for digital. Use some good bypass capacitors.
  Reply With Quote
Old 28th March 2008, 01:57 AM   #3
diyAudio Member
 
hollowman's Avatar
 
Join Date: Jan 2007
Blog Entries: 3
Default Re: V regulation for digital circuits

Quote:
Originally posted by DECKY999
I know that good old 78xx are not made for audio but how about using some more modern regulators.
IMO, a better (but slightly more $$) option in upgrading from 7805 is the LM340-T5 (thx to CarlosFM of diyhifi for that suggestion).

Also, Martin Clark suggested the pre-tracker, found in LM317's datasheet:
- Ref 1
- Ref 2

I've used this pre-tracking regulator with success, but only for "higher" voltages (+/- 15VDC). Not sure how well it'll perform at 5VDC.

Also be aware that you can do quite a lot of tweakling to these regulator ckts afterwards, like snubbering. In DIY, you'll never get bored!
  Reply With Quote
Old 28th March 2008, 02:03 AM   #4
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Well, I tried those: LM317, LM2937, LT1086, LT1129 in CDT prototype and LM7808 was actually the best: http://www.diyaudio.com/forums/showt...36#post1468036
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 28th March 2008, 02:14 AM   #5
diyAudio Member
 
hollowman's Avatar
 
Join Date: Jan 2007
Blog Entries: 3
Quote:
Originally posted by Peter Daniel
Well, I tried those: LM317, LM2937, LT1086, LT1129 in CDT prototype and LM7808 was actually the best...
Peter/all:
The LT's and some low-dropouts are $$ and often claimed to be noisier. Is this what you found?
  Reply With Quote
Old 28th March 2008, 02:17 AM   #6
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
No, I wasn't concentrating on the noise; they just didn't sound as good.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 28th March 2008, 02:34 AM   #7
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Default Re: Re: V regulation for digital circuits

Quote:
Originally posted by hollowman

IMO, a better (but slightly more $$) option in upgrading from 7805 is the LM340-T5 (thx to CarlosFM of diyhifi for that suggestion).
LM340 is the same series as 78xx: http://www.national.com/ds/LM/LM340.pdf
In fact, if you try to order LM7815 from DigiKey, only LM340 comes out.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 28th March 2008, 02:44 AM   #8
diyAudio Member
 
hollowman's Avatar
 
Join Date: Jan 2007
Blog Entries: 3
Default Re: Re: Re: V regulation for digital circuits

Quote:
Originally posted by Peter Daniel
LM340 is the same series as 78xx: http://www.national.com/ds/LM/LM340.pdf
In fact, if you try to order LM7815 from DigiKey, only LM340 comes out.
Yup -- know about the "duplicity" WRT the datasheet (dunno what's up with that ??). I do know that Fairchild 7805's are different from National 7805/LM340T-5.0's: Digi-Key Part Numbers LM7805CT-ND vs. LM340T-5.0-ND, respectively.

IAC, my LM340-T5 looks like CalosFM's image capture of this reg. in this post. It is different from any 7805 I'm using or have ever used -- both in external labeling and performance.

I got mine from Digi-Key.
  Reply With Quote
Old 28th March 2008, 02:57 AM   #9
diyAudio Member
 
DECKY999's Avatar
 
Join Date: Jul 2007
Just to summarize (if I can) as far as the price/performance ratio is concerned good old 78xx are as good as it gets.

The only step-up from there would be some of the super-regulator varieties. However, if I can remeber old posts there were some suggestions that super regs have more or less the same noise levels at high frequencies as the 78xx and that for digital regulation they are waste of money. Does that stand or someone has different experiences?

Reragding the 78xx vs LM340T - they are on the same family spec sheet but the performance is smidgen different ; 40uV vs 50uV voltage noise and a bit better regulation on the LM340 side.

http://www.farnell.com/datasheets/64424.pdf

  Reply With Quote
Old 28th March 2008, 05:16 PM   #10
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Quote:
Originally posted by DECKY999
Just to summarize (if I can) as far as the price/performance ratio is concerned good old 78xx are as good as it gets.

The only step-up from there would be .......
Panasonic AN800x is worth consideration too. In my NOS DAC I prefer them over 78xx
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  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
“Ideal” power/regulation for higher-current digital-section ICs hollowman Digital Source 0 8th April 2008 05:07 AM
Decoupling caps-Alternatives to tantalum capacitors in digital circuits? Dr.H Digital Source 20 21st February 2005 06:01 PM
Capacitors for digital circuits- Tants vs electrolytics Dr.H Digital Source 7 12th February 2003 04:21 PM
Sulzer Regulators vs LT1085 in digital circuits Dr.H Digital Source 0 29th July 2002 06:56 AM
Regulators for digital circuits Peter Daniel Digital Source 49 5th July 2002 11:58 AM


New To Site? Need Help?

All times are GMT. The time now is 03:15 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2