24VDC to ~15VDC without a regulator - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 30th May 2012, 09:56 PM   #1
diyAudio Member
Join Date: Dec 2007
Location: Oslo
Default 24VDC to ~15VDC without a regulator


I have a simple audio preamplifier that uses two TL072 op amps, but my supply is ±24V and the TL072's has a max supply voltage of ±18V. The proper way to do this would be using regulators, but I have none available and getting them can take days where I live. A second possibility is using only the +24V rail and operating the opamps with biased inputs, but this involves a lot a coupling capacitors so I'd rather avoid it.

My question is this: is it safe/sane to use a simple voltage divider on both rails (eg. two 1.5k 1W resistors) to get the voltage down to say ±12V (which is ample for my circuit)? The op amps will drive only high impedance sources (>10k) so I would not expect the output current to load the voltage divider so much that the supply voltage drops noticeable, but I'm not 100% sure. What other considerations do I need to make?

Any thoughts are appreciated and my apologies if this already has been answered on the forums!
  Reply With Quote
Old 31st May 2012, 12:34 AM   #2
diyAudio Member
Join Date: Apr 2003
Location: Portland,Oregon
Blog Entries: 4
Send a message via AIM to DigitalJunkie
It could work. You'll probably want to try to use the lowest value resistors in the voltage dividers that you can,this will help get the supply impedance down a bit,and the voltages possibly more stable,at the expense of extra power (heat) in the resistors,and extra load on the power transformer.
  Reply With Quote
Old 31st May 2012, 01:37 AM   #3
wwenze is offline wwenze  Singapore
diyAudio Member
Join Date: Mar 2008
Add electrolytic caps between the +12V and ground (same for -12V) to reduce the power supply impedance for AC frequencies.
  Reply With Quote
Old 31st May 2012, 06:17 AM   #4
diyAudio Member
Join Date: Dec 2007
Location: Oslo
Excellent, thanks a lot guys! I will give it a try.
  Reply With Quote
Old 31st May 2012, 06:55 AM   #5
Elvee is offline Elvee  Belgium
diyAudio Member
Elvee's Avatar
Join Date: Sep 2006
Don't you have zeners available? That would be preferable to a resistive divider.
If you don't have any zeners, you could substitute Vbe multipliers. Or, if you have zeners of the wrong voltage, an hybrid Vbe+zener multiplier.
. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
  Reply With Quote


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
When you need +/- 15VDC and have only one pole jackinnj Power Supplies 21 9th November 2016 10:55 PM
+/- 15vdc psu help rockstudio Power Supplies 3 3rd March 2006 05:51 AM
15vdc amp bjackson Chip Amps 6 18th August 2005 12:52 AM
+/- 15VDC from +/-75Vdc Is there a better way? Zero Cool Power Supplies 19 1st July 2005 12:41 PM
Low power supply (+/-15VDC) SupraGuy Car Audio 5 25th August 2004 05:11 PM

New To Site? Need Help?

All times are GMT. The time now is 02:30 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2