Standby mode and speaker turn on delay together? - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 1st September 2012, 07:44 AM   #1
diyAudio Member
 
Join Date: May 2010
Default Standby mode and speaker turn on delay together?

Hi everyone!

My goal is to build an integrated stereo amp based on the LM3886, that will include a soft switch (that activates a relay witch connects the main transformer to the mains) , and a DC protection circuit with a turn on delay.

I relized that i can't use the same 12VDC power rail for the soft switch and the speaker protection together, because the soft switch transformer will have to be always on, and the DC protection circuit will have to be switched on when the main transformer is switched on, for the turn on delay to occur.

so how can i combine those two circuits together? do i need to use separate transformers or maybe use a voltage regulator to lower the voltage from the main transformer (about 30VDC for the LM3886) to 12V for the protection circuit? wouldn't it be wasteful?

I always wondered how does it designed in commercial amps?

tnks for the helpers
  Reply With Quote
Old 1st September 2012, 11:11 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
A separate small transformer to power the start up control circuits.

You can run the delay trigger from either the main transformer, or from a tapping on the soft start trigger output.

The delay circuit itself can be powered by either transformer. It's the trigger signals that need to be sequenced.
__________________
regards Andrew T.
  Reply With Quote
Old 1st September 2012, 03:30 PM   #3
diyAudio Member
 
Join Date: May 2010
Hi Andrew! I think i understood your second option, you ment that the softstart output will activate 2 relays, something like this:
Click the image to open in full size.
I didn't understand your first option though, the main voltage is 30V and the DC protection circuit voltage is 12V
  Reply With Quote
Old 1st September 2012, 04:55 PM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Use an lm7812, to cut the 30Vdc to 12Vdc.
__________________
regards Andrew T.
  Reply With Quote
Old 1st September 2012, 06:09 PM   #5
diyAudio Member
 
Join Date: May 2010
Witch option do you recommand using? is a regulator commonly used for this purpose?
and also i would like to know if using the 12V from the regulator will be ok for an active tone control?

tnks alot Andrew
  Reply With Quote
Old 4th September 2012, 07:42 PM   #6
diyAudio Member
 
Join Date: May 2010
Guys a little help please?
I need to know how this is supposed to be done, i don't really want to use the LM7812 becuse 30V is it's limit.
if you can refer me to a project where a similar thing has been done, it will also help.

tnks again
  Reply With Quote
Old 5th September 2012, 08:40 AM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
lm317 as a pre regulator.
__________________
regards Andrew T.
  Reply With Quote
Old 5th September 2012, 04:19 PM   #8
diyAudio Member
 
Join Date: Mar 2007
Location: California
Quote:
Originally Posted by TiGeRGuY View Post
Guys a little help please?
I need to know how this is supposed to be done, i don't really want to use the LM7812 becuse 30V is it's limit.
if you can refer me to a project where a similar thing has been done, it will also help.

tnks again
You can also use a LM7824 as a pre-regulator (use it first and send its output to the input of the LM7812). The LM7824 has an input voltage limit of 40V.

-Charlie
  Reply With Quote
Old 5th September 2012, 07:50 PM   #9
diyAudio Member
 
Join Date: May 2010
tnks for your answers! i read that linear regulators are very inefficient, is it the best option i have?
Based on what you say, if i'll open my old yamaha AV reciever i should find a regulator for this purpose?

i am very confused, i searched the web for weeks to find how this thing works and i just can't find anything.

i was also counting on using the "after turn on" 12V rail for a sound control (some little opamp's), and i always hoped it will run from a pure 12V rail.

if you say this is the method manufacurers use, i will go for it.
  Reply With Quote
Old 6th September 2012, 07:55 AM   #10
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
build something simple and get it working. Then expand your knowledge and try some simple experiments.
Then you should be ready to try working out what you need and how to implement the sequencing.

Trying to develop a specification before you know what can be done is almost impossible.
__________________
regards Andrew T.
  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
Speaker Turn On Delay and DC Protector Board Set (V2) Ana The diyAudio Store 165 16th March 2014 05:20 PM
need LM1876 mute mode and standby mode help JozzaG Chip Amps 21 19th January 2012 05:28 PM
Stuck in standby mode jmillerdoc Solid State 3 8th March 2010 06:45 PM
Aleph-x standby mode yup Pass Labs 16 19th January 2007 01:59 AM
Aleph-X standby mode (once again...) CheffDeGaar Pass Labs 3 3rd September 2003 07:03 PM


New To Site? Need Help?

All times are GMT. The time now is 01:10 AM.


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