Another ChipAmp running

[12 Cents]

Hello,

since I found this forum I wanted post some "Hello post" with a project worth showing. So please take this as a kind of introduction post from me, ok ?

The amplifier is a LM3886 in a datasheet-like fashion like proposed by Mr. SL. I left out Ci, 17mV DC offset at the outputs with a source attached. Without, ~70mV. It worked (almost) from the start and sounds just good.

My thanks go to the designers and manufacturers of these great little chips.

theduke

 

[12 Cents]

Also my true thanks go out to the makers and all the contributors of this forum. This is great.

 

[Mick_F]

It looks as if you have some quite big caps in the PS. Do you have some snubbers close to the supply bypassing caps of the amp to account for this? If not, there might be some serious improvement possible here.

Mick

 

[12 Cents]

Yes, I cloned Carlos' snubbered filter section with 2x10mF per rail. Slight problem: I measure 100mV less voltage on the negative rail (after the filter R's)

Regards,
theduke

Mick, I like your photography

 

[Mick_F]

I measure 100mV less voltage on the negative rail (after the filter R's)

Did you check the values of all capacitors and resistors involved? A difference of 100mV is less than one percent of the rail voltages and might be explained within the parts' tolerances.

Mick, I like your photography

Thanks

 

[12 Cents]

It must be the bleeders, which act as virtual ground creators in my case too. Should the circuit ground be earthed?

 

[12 Cents]

Feedback resistor, Mute resistor

 

[Mick_F]

Thats a good idea to put the mute resistor directly onto the pins.

Btw. Where do you buy your parts in Germany?

Mick

 

[12 Cents]

Bei Reichelt

The LM's are from a forum guy, brunoravera...

 

[slackman]

Hi Mick,
drop me a line if you're interested in LM-chips. I still have some samples stocked.

If you pay the transport fee, National will also send samples to you (I think). The only point is you must create an account and you should have a credit card...

My first sets (LM4780) i bought from Peter Daniel , really nice work and price is ok.

Heho Elektronik also has the LM3886 in T and TF for about 9,- Euros and some other LMs too (no 4780... ).

Michael

PS: Great photos, I like this style...

 

[Mick_F]

I should say that I am also aware that Farnell has a German site and sells the Chips (as well as many other things). I was just curious what your sources are.

Mick

 

[slackman]

Farnell only sells to companies - no deal for private ones. So if to 'build' a company, why not ordering samples?

I asked Reichelt several times to take the LM3886 and 4780 into stock - they don't want to.

Same with the LM338 power supply: they only have the expensive TO3 version, TO220 would cost 10th of the TO3 and layout is much more simpler/smaller.

I know Heho from past times (15 years ago), where i first came in contact with electronics.

Michael

 

[Mick_F]

Farnell only sells to companies - no deal for private ones.

I never had problems to order....

Mick