Single Sided LM3886

samsom · 15th August 2011, 09:08 AM

Hi Guys..Please check this Single layout for Me please

The Attachments include the pcb layout and schematic layout..Thanks in advance

pacificblue · 15th August 2011, 09:53 AM

No smoothing caps?
No decoupling caps?
What are the functions of R3, R4, R5, C8, C9 and C10?
Will R1=15k, R6=1k and R7=20k lead to low offset voltage at the output?
C4 is no electrolytic. C1 should not be electrolytic, but if you use one, it will certainly have a smaller footprint.
Most traces are too narrow as are the spaces between the power and speaker traces.
Many traces are unnecessarily long and meandering about like drunk.
Signal traces should be as far as possible apart from power and speaker traces to avoid cross-talk.
Too many unnecessary jumpers.
Pads with no obvious function.
Arbitrary mounting holes.

Aucosticraft · 15th August 2011, 10:46 AM

Huge lot discussions are already done on routing LM3886 PCB. search & read them, you will find lot of guidelines. and then refine your layout.

AndrewT · 15th August 2011, 10:54 AM

separate the Signal Ground from the Power Ground.

The Power Ground includes the Speaker Return and Zobel Return and Decoupling Ground and PIN7 and Mute ground and Safety Earth (on the metal Chassis) and Zero Volts. The Metal chassis must be connected directly and permanently to the mains cable PE.

The Signal ground must include the Input/Signal Return, the Rin Return, the NFB from C3 (DC blocker) and the RF attenuator (which is missing).

What is VR1?

samsom · 15th August 2011, 12:52 PM

Hi guys, Thanks for replies..

I used the following schematic for my design..Im not too familiar with what some of the components do...

Ive built lm3886's before and they work fine..but for some reason, they all seem to "blow up" when I raise the volume to a certain level.

After some trials I decided to buy this board from Ebay:

LM3886TF LM3886 Amplifier Board DIY Components KIT | eBay

It Worked fine until I raised the volume again.

I dont know If the power supply is the problem, Im using the following torroid:

P042K 160VA Toroidal Transformer 0-35, 0-35 Vac Outputs | eBay

with 1000uF 50V Caps

(VR1 is a 10k Pot)

pinkmouse · 15th August 2011, 01:11 PM

Your traffo is too big. 35V rectified (35x1.41) gives you rails of near enough 50V, way higher than the chips are rated for.

samsom · 15th August 2011, 01:13 PM

I would have thought so. I decided to look into building a voltage regulator..I was taught that zener diodes could be of some use but not really sure..

pinkmouse · 15th August 2011, 01:43 PM

I've never been a fan of regulating chip amps, but there are many threads here that discuss it if you search.

15th August 2011, 09:53 AM	#2
pacificblue diyAudio Member Join Date: May 2008	No smoothing caps? No decoupling caps? What are the functions of R3, R4, R5, C8, C9 and C10? Will R1=15k, R6=1k and R7=20k lead to low offset voltage at the output? C4 is no electrolytic. C1 should not be electrolytic, but if you use one, it will certainly have a smaller footprint. Most traces are too narrow as are the spaces between the power and speaker traces. Many traces are unnecessarily long and meandering about like drunk. Signal traces should be as far as possible apart from power and speaker traces to avoid cross-talk. Too many unnecessary jumpers. Pads with no obvious function. Arbitrary mounting holes. __________________ If you've always done it like that, then it's probably wrong. (Henry Ford)

15th August 2011, 10:46 AM	#3
Aucosticraft diyAudio Member Join Date: Nov 2009 Location: Pune	Huge lot discussions are already done on routing LM3886 PCB. search & read them, you will find lot of guidelines. and then refine your layout. __________________ There is always a first time....

15th August 2011, 10:54 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	separate the Signal Ground from the Power Ground. The Power Ground includes the Speaker Return and Zobel Return and Decoupling Ground and PIN7 and Mute ground and Safety Earth (on the metal Chassis) and Zero Volts. The Metal chassis must be connected directly and permanently to the mains cable PE. The Signal ground must include the Input/Signal Return, the Rin Return, the NFB from C3 (DC blocker) and the RF attenuator (which is missing). What is VR1? __________________ regards Andrew T.

15th August 2011, 01:11 PM	#6
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Your traffo is too big. 35V rectified (35x1.41) gives you rails of near enough 50V, way higher than the chips are rated for. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

15th August 2011, 01:43 PM	#8
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	I've never been a fan of regulating chip amps, but there are many threads here that discuss it if you search. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort


	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

15th August 2011, 12:52 PM	#5
samsom diyAudio Member Join Date: Jun 2011	Hi guys, Thanks for replies.. I used the following schematic for my design..Im not too familiar with what some of the components do... Ive built lm3886's before and they work fine..but for some reason, they all seem to "blow up" when I raise the volume to a certain level. After some trials I decided to buy this board from Ebay: LM3886TF LM3886 Amplifier Board DIY Components KIT \| eBay It Worked fine until I raised the volume again. I dont know If the power supply is the problem, Im using the following torroid: P042K 160VA Toroidal Transformer 0-35, 0-35 Vac Outputs \| eBay with 1000uF 50V Caps (VR1 is a 10k Pot)

15th August 2011, 01:13 PM	#7
samsom diyAudio Member Join Date: Jun 2011	I would have thought so. I decided to look into building a voltage regulator..I was taught that zener diodes could be of some use but not really sure..

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
The yet tiniest single-sided LM3886?	hurtz	Chip Amps	228	21st May 2012 01:54 AM
lm3886 single sided pcb	ryan750	Chip Amps	20	30th March 2012 04:11 AM
Bridged LM3886 from single-sided supply	ventle	Chip Amps	10	16th October 2010 11:14 AM
Lm3886 single sided my first try	ampimp	Chip Amps	0	14th October 2010 10:08 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read