Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

power up electronic devices with audio amplifier output
power up electronic devices with audio amplifier output
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 28th January 2018, 03:53 PM   #1
Joanito is offline Joanito  Portugal
diyAudio Member
 
Join Date: Mar 2017
Location: Maia, Porto
Default power up electronic devices with audio amplifier output

Hello people,

Can i use my commercial amplifier as a power supply, per example, for my laptop. I mean, if we provide at the input of the amplifier , per example , 700mVdc , then in a perfect world, in the output of the amp should be a dc signal with the amplitude controlled by the volume pot, right ? A good comercial amplifier can provide, per example, continuous 19vdc for a laptop (let's say about 4 A ) ? . If the ampllifier can drive loads of 4 ohm, it should also can power up the laptop, right ? What about if it is not a laptop and if it is a 12vdc led lamp ? It's easier for the amplifier because it's less current, right ?
The tension at the output of the amplifier will be a flat line, with little ripple, or not at all ( it will drop too much )?

Thanks guys.
  Reply With Quote
Old 28th January 2018, 04:44 PM   #2
nigelwright7557 is online now nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Its not a very safe way to power a laptop.
If you go over voltage you could fry the laptop.

You will need quite a high powered amp to power it.
Audio amps aren't usually set to a dc voltage, they are constantly changing with each output transistor taking turns driving the speaker.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 28th January 2018, 05:56 PM   #3
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
A voltage regulator is a DC power amplifier
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 28th January 2018, 06:04 PM   #4
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
power up electronic devices with audio amplifier output
As Nigel says... not recommended.

You will also find most amps are AC coupled in at least two places and so always have a gain of unity at DC.

Its definitely not a good idea imo.
  Reply With Quote
Old 28th January 2018, 06:29 PM   #5
Joanito is offline Joanito  Portugal
diyAudio Member
 
Join Date: Mar 2017
Location: Maia, Porto
Yes, but in last ressouce, if i dont have other power supply or transformer, it will work, right ? The amplifier that i have here is 100w 8 ohm per channel... so yes, it will reach 19vdc or 12vdc... And if i, some day, need to do this, i will put a multimeter measuring the voltage at the amplifier output ( i will see the voltage as i turn the volume pot ). I already tried for led lamp of 12vdc... But i tryed with a sine and square wave at various frequecies... the lamp lights and flashes according to the frequency... What i really want to know is if it will work reasonably with a dc signal... Again, in last ressource...

Thank You
  Reply With Quote
Old 28th January 2018, 06:42 PM   #6
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
No, because as Mooly says it will have unity gain at DC (almost guaranteed)
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 28th January 2018, 07:15 PM   #7
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
power up electronic devices with audio amplifier output
That's right, and just to add a bit more... if its AC coupled anywhere in the signal chain the DC gain is zero. Most power amps are unity gain due the feedback return network, add in the other AC coupling up front and we get zero gain at DC.
  Reply With Quote
Old 28th January 2018, 07:55 PM   #8
Joanito is offline Joanito  Portugal
diyAudio Member
 
Join Date: Mar 2017
Location: Maia, Porto
ok, i did a google search and i already understand what you guys mean... you mean only ac passes throu capacitor... I had not thought of that...

Thanks guys.
  Reply With Quote
Old 28th January 2018, 08:11 PM   #9
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
That's right, and even if the amplifier were dc coupled there is a capacitor in the feedback circuit which controls the gain so that that it can't amplify dc
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 28th January 2018, 08:23 PM   #10
Joanito is offline Joanito  Portugal
diyAudio Member
 
Join Date: Mar 2017
Location: Maia, Porto
ok, thanks
  Reply With Quote

Reply


power up electronic devices with audio amplifier outputHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Commercial Audio Brands: N-Ch/NPN only output devices in a push pull power follower tiefbassuebertr Solid State 0 11th May 2011 10:15 AM
fairchild semi, new audio output devices unclejed613 Solid State 85 29th July 2008 06:52 AM
how to mount output devices of amplifier? Wagener Solid State 8 9th April 2004 08:42 AM
Amplifier -adding extra output devices norvbul Solid State 1 30th April 2003 07:10 PM


New To Site? Need Help?

All times are GMT. The time now is 10:10 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki