i have just made the gc from http://sound.westhost.com/project19.htm but with the lm3886 instead and this psu http://sound.westhost.com/project04.htm but with 4700 caps instead.. im using a 2*24v 300va trafo
i have no pcb so i have just wired the components together..
the big problem is large noise/hum and a tiny bit of music...
i cant see what i have done wrong... can you experts give me a hint what i have done wrong???
sorry about my poor english
i have no pcb so i have just wired the components together..
the big problem is large noise/hum and a tiny bit of music...
i cant see what i have done wrong... can you experts give me a hint what i have done wrong???
sorry about my poor english
If you haven't downloaded the datasheet and the AN-1192 do it 
because there is everything you need.
http://www.national.com/an/AN/AN-1192.pdf
http://cache.national.com/ds/LM/LM3886.pdf
because there is everything you need.http://www.national.com/an/AN/AN-1192.pdf
http://cache.national.com/ds/LM/LM3886.pdf
Wuffer, if it helps to copy a 'tried and tested' design for the LM3886, here is the one that I built. I have not had time yet to write up the full description of the build on Decibel Dungeon.
The orange square is the signal star ground. And note that this was with a snubberized PSU. If you don't want to use that PSU, substitute the 100uF caps on the voltage pins for 1000uF and leave out the big caps at the bottom of the diagram.
The orange square is the signal star ground. And note that this was with a snubberized PSU. If you don't want to use that PSU, substitute the 100uF caps on the voltage pins for 1000uF and leave out the big caps at the bottom of the diagram.
An externally hosted image should be here but it was not working when we last tested it.
much closer now... i think the wire i have used is bad.. it influence the sound in a bad direction... not sure what to do...
damn the lm3886 is getting hot. hat hoped that a heatsink from a p4 could be used but no
but now there is music coming out of the speaker instead of noise.. now i just have to get the last noise away
damn the lm3886 is getting hot. hat hoped that a heatsink from a p4 could be used but no
but now there is music coming out of the speaker instead of noise.. now i just have to get the last noise away
Unlikely.wuffer said:
If the 3886 is getting hot, then your amp is probably oscillating badly. I've used heatsinks much smaller than a P4 one, and at low to medium volumes, the chip gets only slightly warm.Originally posted by wuffer damn the lm3886 is getting hot. hat hoped that a heatsink from a p4 could be used but no
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Tear it down and start again from the ground up. Nuuk's diagram looks solid; try following that.
Here is something else for you to look at Wuffer. It shows both channels of a 3886 GC and how to connect them together properly. If you follow this carefully, you should have a cool-running, non-oscillating, noise-free and musical GC!
An externally hosted image should be here but it was not working when we last tested it.
To makes things a little clearer:
The 0R22 resistor on the output should be rated at 3 watts. Many of us are using two 0R47 2 watt carbon film resitors in parallel.
The Zobel is a 100nF capacitor in series with a 2R7 resistor.
As Mateo88 says, the DC blocker is a capacitor (2.2uF-4.7uF) that lets the signal (AC) through but blocks DC.
Looking at a schematic will also be useful but the 'layout' diagrams are useful to show people where the parts go!
The 0R22 resistor on the output should be rated at 3 watts. Many of us are using two 0R47 2 watt carbon film resitors in parallel.
The Zobel is a 100nF capacitor in series with a 2R7 resistor.
As Mateo88 says, the DC blocker is a capacitor (2.2uF-4.7uF) that lets the signal (AC) through but blocks DC.
Looking at a schematic will also be useful but the 'layout' diagrams are useful to show people where the parts go!
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