Amps for PC Speakers - Page 21 - 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 15th June 2014, 09:57 PM   #201
diyAudio Member
 
Join Date: Feb 2011
Yess, there is a need for a switch. and it goes from pin 11 to V+.
not GND.

If You power on that powersupply, it may for a very short time while powering up exceed 18 volts. if the mute/standby/play pin is tied to V+ (even via cap+resistor) it can happen that You instantly kill the chip. Spikes can happen. And will.
  Reply With Quote
Old 15th June 2014, 10:24 PM   #202
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 10
Antonio, I would not be happy running the caps that close to their rating; a much bigger margin is more my style ...
__________________
Frank . . . the truth is, I just like a bit of ASMR ...
  Reply With Quote
Old 15th June 2014, 11:49 PM   #203
diyAudio Member
 
apassgear's Avatar
 
Join Date: Nov 2002
Location: Viña del Mar, Torreon
Ok so in one position connected to V+ and open on the other for stand by so I won’t need a power switch which at this moment of development is a plus.

Good advice, thks
  Reply With Quote
Old 16th June 2014, 12:21 AM   #204
diyAudio Member
 
apassgear's Avatar
 
Join Date: Nov 2002
Location: Viña del Mar, Torreon
Though it wasn’t the initial goal I’m doing a separate amp for the satellites since it won’t fit inside the original box which includes transformer electronics plus the woofer even for the smaller pcb I did before was going to be a hazel to have it almost touching the speaker and trafo.

Now we will have a 60 VA EI transformer, diode bridge with 10mF first smoothing a small choke and 2x 2.2mF plus one 270u Oscon at each power feed for decoupling.

Yes Frank, 15V sounds too close, need to continue adjusting the secondary to get around 14V DC at the amp feed point.
  Reply With Quote
Old 16th June 2014, 04:22 PM   #205
diyAudio Member
 
Join Date: Feb 2011
use a diode in series on V+ and it will drop enough to be safe.
  Reply With Quote
Old 17th June 2014, 12:41 AM   #206
diyAudio Member
 
apassgear's Avatar
 
Join Date: Nov 2002
Location: Viña del Mar, Torreon
Yes Arty, that will do but prefer it the hard way. That transformer has been set to different voltages in the past so one more time won’t hurt and it’s easy to do on an EI type with separate primary and secondary windings.

Antonio
  Reply With Quote
Old 19th June 2014, 10:54 PM   #207
diyAudio Member
 
apassgear's Avatar
 
Join Date: Nov 2002
Location: Viña del Mar, Torreon
Quite happy with how everything is coming up with the new build, in fact almost finish, missing da switch for the mute/stand-by. The supply was tested 2 days ago and ready to go at 14.3V with no load, and sagged to 12.8V @ 2.5A with R load.

So we might be hearing some music tomorrow...

Last edited by apassgear; 19th June 2014 at 11:00 PM.
  Reply With Quote
Old 20th June 2014, 09:27 PM   #208
diyAudio Member
 
Join Date: Feb 2011
that seems nice, can't wait to hear Your opinion about the amp it self, once it is finished

then we can get to some tweeking.
  Reply With Quote
Old 21st June 2014, 03:56 AM   #209
diyAudio Member
 
apassgear's Avatar
 
Join Date: Nov 2002
Location: Viña del Mar, Torreon
In a few moments I will start testing this small amp but in the meanwhile Arty what’s the deal with pin 12 (V ref)?

On page 4 c. paragraph of the Philips spec sheet says that harmonic distortion on low freq can be decreased if two diodes are connected to gnd from pin 12.

Then on page 7 note 8 says that ripple rejection can be dropped by 7dB, again if the 2 diodes are connected to gnd from same pin.

It’s an easy addition those 2 diodes to gain in HD and RR, my question would be if these diodes are connected in parallel in reverse polarity? The spec sheet doesn’t give a clue as far as I have seen.

Looking forward to tweaking tips!

Antonio
  Reply With Quote
Old 21st June 2014, 04:34 AM   #210
diyAudio Member
 
apassgear's Avatar
 
Join Date: Nov 2002
Location: Viña del Mar, Torreon
This time around test went smoothly. One side has less than 1 mV the other has 24 mV which is well within spec, in mute position is near 0 mV but didn’t record the number. Test was done with grounded source (0 Ohms) at the input and open outputs (no load).

Need to add a bleed resistor at the supply, those caps are really good they maintain the voltage for hours.

Next will be some

Antonio

Last edited by apassgear; 21st June 2014 at 04:36 AM.
  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
Big sale thread: PHL, Raven, Amps, In-wall/ceiling speakers, Amps, VideoRequest mbcouple Swap Meet 2 27th October 2008 10:27 PM
PC Cooling Fans for Tube Amps Dominguez Tubes / Valves 4 19th August 2007 01:06 AM
Why not mod a PC case for amps? UrSv Parts 15 14th February 2005 06:44 AM
DJ Speakers.... Worse than PC Speakers Mikett Multi-Way 34 14th January 2004 05:06 PM


New To Site? Need Help?

All times are GMT. The time now is 11:55 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