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

LM3886 Power Supply Schematic?
LM3886 Power Supply Schematic?
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 16th January 2004, 02:30 AM   #1
newbie1 is offline newbie1  United States
diyAudio Member
Join Date: Jan 2004
Location: California
Default LM3886 Power Supply Schematic?


I am contemplating building a gainclone from the LM3886T chip. I have seen a lot of good schematics for the amp itself, but does anyone have any for the power supply? What about caps? I have seen people use 1000uF up to 10000uF any recommendations? I want to ultimately use this as a subwoofer amp. Does anyone have any opinions on how the the LM3886 would perform as a sub amp?

  Reply With Quote
Old 16th January 2004, 05:23 AM   #2
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
peranders's Avatar
Join Date: Apr 2002
Location: Göteborg, Sweden
LM3886 Power Supply Schematic?
Have you read this:
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote
Old 16th January 2004, 11:35 AM   #3
soundNERD is offline soundNERD  United States
diyAudio Member
Join Date: Sep 2003
Location: Illinois
The reason people use 1,000uf per rail is if they want poor bass responce, but excelent mids and highs. This is good if you have a subwoofer along with the speakers you drive with the 3886.

Otherwise, I reccommend a least 8,000uf.

Heres a pcb layout I designed. It can take any combination of up to 4 caps per rail:
Attached Files
File Type: zip power supply mirror.zip (7.1 KB, 607 views)
  Reply With Quote
Old 16th January 2004, 12:16 PM   #4
newbie1 is offline newbie1  United States
diyAudio Member
Join Date: Jan 2004
Location: California
Originally posted by crown300
What size sub? Type of enclosure?

for a 6.5" maybe one amp will do, but I prefer a bridge.
8" definately a bridge.
10" and up, not enough power.
Well, I was hoping to use a 4 ohm 12" sub. But I guess that's not going to happen huh? What are the bridging possibilities of the LM3886 for driving a 12" sub? If I am reading the docs from NS correctly there are configurations with multiple chips that can produce 200W, or is this a pipe dream?

  Reply With Quote
Old 16th January 2004, 01:39 PM   #5
macboy is offline macboy  Canada
diyAudio Member
Join Date: Oct 2003
Location: Ottawa, Canada
With a 4 ohm speaker, your options are a little bit more limited. You cannot simply use a bridged amp, since the effective load on each chip will be half the speaker impedance, or 2 ohms. That is simply too low if you expect to get high power output from the chips.

A much better option is to parallel two chips. This will make the effective load for each chip to be twice the speaker impedance, or 8 ohms. Now you just have to design the power supply according the to information for an 8 ohm load. The voltage of the supply is important; check out the graph "Output power vs. supply voltage" in the datasheet. Keep in mind that you have two amps, each effectively driving 8 ohms, so find the power output for an 8 ohm load and your power supply voltage, and then multiply by 2.

Another option is a bridged-parallel design. Both this and the parallel design are deailed in the National app note AN1192. Here, the effective load for each of the chips is the same as the speaker impedance, but you get around 4 times the output power as a single chip. Again, the voltage of the power supply is very important.

Don't forget when choosing a transformer that the final DC voltage after rectifying and filtering is 1.414 times as high as the AC voltage. This is because the DC voltage will be as high as the peak of the AC sinewave, but AC voltages are given as RMS values, which is like an average of the sine wave. So if you want +-35 Volts DC, you need a transformer with two 25 VAC secondaries, or a 50 VAC center tapped.
  Reply With Quote


LM3886 Power Supply Schematic?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
LM3886 Power supply jfnewell1965 Power Supplies 29 30th January 2017 10:56 AM
Power supply for LM3886 brconner Chip Amps 7 23rd June 2008 01:48 PM
Power supply for LM3886 gcds Power Supplies 10 24th March 2007 06:32 AM
LM3886 power supply suggestions? DrFrankenstein Chip Amps 7 7th February 2007 09:16 PM

New To Site? Need Help?

All times are GMT. The time now is 09:11 AM.

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