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

Chip Amps Amplifiers based on integrated circuits

Another BPA200 post: Need some advice on finalizing design
Another BPA200 post: Need some advice on finalizing design
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 7th February 2018, 05:34 AM   #1
sr2002 is offline sr2002  United States
diyAudio Member
 
Join Date: Jul 2005
Location: Texas
Talking Another BPA200 post: Need some advice on finalizing design

After building the BA100 with P2p a few years ago, I'm trying to challenge myself to build the BPA200. I am planing to use the diagram from the AN-1192 document. I have a few questions that I will list below:

1) I am planing to do P2p for BPA200 as well, any drawbacks to this? (considering the extra opamp stages, I'm wondering if this circuit is more prone to stray noise or inductance introduced by long traces or p2p connections)

2) Are there any further modifications recommended to the schematic from figure 13 in the document or is that design good enough?

3) For TVS1 and TVS2 I couldnt find the exact part number from the BOM so I ordered the following, please let me know if it would work/alternatives: Mouser part: 511-1.5KE100CA

4) LF411ACN is not readily available, so I substituted LF412ACN and LF411ACN with LF411CN and LF412CN. The only difference I saw as max input voltage and differential voltage on the non ACN part is slightly lower. Max supply voltage is also lower, but the 15v supply should be within range. Please let me know if this substitution would cause any issues

5) Another substitution I did was for the voltage regulators on the 15v supply. I am using instead MC78L15ABPG and MC79L15ABPRPG,

6) Any recommendations on Torroidal trafos to buy in the US? I am planing to buy two Avel Lind. 30+30v 330VA units (one for each channel)

7) Any recommendation for wire gauge for PCB power connections and speaker output connections?

8) Further down the road, looking for some enclosure recommendations, ideally ones that have heatsinks built into the side walls.

Whew! that was a lot to remember ... please feel free to chime in your opinions, any help is appreciated.

(Also, just FYI, I have already read through most of the posts related to this topic and my specific questions have not been answered, hence I am opening a new thread)
  Reply With Quote
Old 7th February 2018, 06:12 AM   #2
Mark Whitney is online now Mark Whitney  Netherlands
diyAudio Member
 
Mark Whitney's Avatar
 
Join Date: Feb 2013
Location: Netherlands
If this is for LM3886 then you want to use a 2x 20 to 24 VAC transformer.
__________________
Regards Mark.
  Reply With Quote
Old 7th February 2018, 06:16 AM   #3
sr2002 is offline sr2002  United States
diyAudio Member
 
Join Date: Jul 2005
Location: Texas
Oh yes, you are right. root(2)*VAC thing hence a 1.4142135624 x 24 about 34VDC. I have forgotten most of those equations ... Will probably get a lower value ... most likely 20VAC trafo in that case
  Reply With Quote
Old 7th February 2018, 06:21 AM   #4
globalplayer is offline globalplayer  Germany
diyAudio Member
 
globalplayer's Avatar
 
Join Date: Oct 2014
Location: =)
7) 13 AWG
__________________
◢◣◢◣◢◣◢◣◢◣
  Reply With Quote
Old 7th February 2018, 01:55 PM   #5
sr2002 is offline sr2002  United States
diyAudio Member
 
Join Date: Jul 2005
Location: Texas
Thank you ��. Any takers for the rest of the questions please?
  Reply With Quote
Old 8th February 2018, 03:53 AM   #6
sr2002 is offline sr2002  United States
diyAudio Member
 
Join Date: Jul 2005
Location: Texas
Bumping thread
Also another question I wanted to add:
The BPA200 schematic from figure 13 does not show the mute circuit. How does that need to be handled ? Do I connect pin 8 from all the Lm3886s to -V with a calculated resistor in series ? Or did there any additional components or topology required ?
  Reply With Quote
Old 8th February 2018, 09:14 AM   #7
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
9.)
I would link all the mute pins together. Then feed them to a common CR to give the delayed mute/unmute function.
Remember that each 3886 needs unmute current and that will affect the value of the resistor since it has to draw the sum of those unmute currents.

8.)
Leave selection of an equipment box until AFTER you have completed all your testing and modifications to get it working properly.
Then fold up the various modules into apackage that would fit a box and re-test to ensure the folding does not affect performance.
Once you have reached this stage measure the size rwequired to enclose the folded assembly and order your box.

7.) the average currents will all be quite low and it is these average currents that determine the heating effect in the wires.
The maximum Vdrop across a resistance is determined by the resistance value times the peak instantaneous current. This Vdrop is being totally dependent on resistance is a more useful concept.
On this basis, I find that resistance (in milli-ohms) along the wires traces/connectors to be a much more useful guide to selecting size for any duty.

5.)
the L version have a low dissipation limit. I suggest you don't use any more than 50% of Pmax.

4.)
the 411 is a jFET input single opamp. There are many other newer jFET input opamps that are equally good or better for servo duty.
The 412 is a dual version of the 411. You cannot swap between single and dual, the pin out is different.

Can you give me a link to where Ti have hidden National's BA100 ap note?
__________________
regards Andrew T.

Last edited by AndrewT; 8th February 2018 at 09:30 AM.
  Reply With Quote
Old 8th February 2018, 02:05 PM   #8
sr2002 is offline sr2002  United States
diyAudio Member
 
Join Date: Jul 2005
Location: Texas
Hi @AndrewT thanks for the detailed response. My follow up questions are:
9) how would I calculate the total Rm and Cm if I connect all mute pins for 4 LM3886s to -V @ 35VDC?

5) do you mind elaborating what you mean by Pmax? If you mean power dissipation, I was assuming these regulator ICs would be running pretty cool since all they are driving is the LF411 and LF422 which aren’t part of the driver stage. Any suggestions for alternatives that would work ? I am planing on using either +-24VAC 330VA x 2 or 1000VA x1 (due to cost of the particular trafos.

4) I was actually able to find the 411ACN and 412ACN as mention in the data sheet. Do you have any suggestions for alternative servos that are better ?

I don’t remember where I got the app notes from for BA100 but following is my thread all the way back from 2005: my new lm3886 amp!!!!!!!
  Reply With Quote
Old 8th February 2018, 05:18 PM   #9
00940 is offline 00940  Belgium
diyAudio Member
 
00940's Avatar
 
Join Date: Sep 2003
Location: Liège
Quote:
Originally Posted by AndrewT View Post
Can you give me a link to where Ti have hidden National's BA100 ap note?
I don't know for the BA100 (typo ?) but the BR100, PA100 and BPA200 are here:
http://www.ti.com/lit/an/snaa021b/snaa021b.pdf

I can't say I'm a big fan of the bpa200 design. Since there are already quite a few opamps used, I'd rather use a differential line driver in front and have all the amps either inverting or non-inverting. It would allow to have 4 identical small pcb for the amps (with onboard servoes) and a small pcb for the front end.

I'm also a bit perplexed by the fact that they left out all the "optionnal" stability components.
__________________
All that is excessive is insignificant. Talleyrand
  Reply With Quote
Old 8th February 2018, 05:27 PM   #10
sr2002 is offline sr2002  United States
diyAudio Member
 
Join Date: Jul 2005
Location: Texas
Do you have a better reference design that you suggest ? I already ordered parts for BPA200 ... but most of the expensive stuff should work any any design.
I liked the shine7 design but the schematic on their website is incomplete and I can’t patch the holes they left out.
  Reply With Quote

Reply


Another BPA200 post: Need some advice on finalizing designHide 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
BPA200 LM4780 Board (Unfinished) Design Protoboard Solid State 1 9th May 2015 09:18 PM
Finalizing TDA2050, LM3886 pra3718 Chip Amps 27 14th February 2013 01:05 PM
Finalizing FR125 configuration Voodoo Rufus Full Range 32 19th June 2006 08:40 PM
BPA200 PCB design nterikun Chip Amps 1 13th September 2005 09:39 PM
Finalizing box volume for SS8565-01s, does this look about right ? Jean Multi-Way 14 3rd May 2003 03:28 AM


New To Site? Need Help?

All times are GMT. The time now is 02:09 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki