lm1875 fizzing away probelm

[PetruV]

This is my thread in which i will post all of my work and ask for all of my help.Sadly you cant change the name of the thread,go to last page to see my latest problems
Please excuse my excessive amount of demanded attention,that has been pointed out to me.

 

[PetruV]

An externally hosted image should be here but it was not working when we last tested it.

The black puddle above the 100k resistor at the input is a ground

 

[PetruV]

An externally hosted image should be here but it was not working when we last tested it.

 

[bobodioulasso]

Pin 1 must be at Vcc/2.
Why the two 100k resistors marked red on your schematic? They provide Vcc/2 at input pin.
You need them and the ground can't be as you made it.

 

[PetruV]

Pin 1 must be at Vcc/2.
Why the two 100k resistors marked red on your schematic? They provide Vcc/2 at input pin.
You need them and the ground can't be as you made it.

I was tired and i thought they werent needed and i wanted to see how it sounded,it took me 2 hours to solder all that crap in cause my soldering iron sucks and i never used perfboard

 

[bobodioulasso]

You must follow the schematic for single supply.
Have a look at datasheet.
When +/- supply is used those resistors are not needed because the input pin , referenced to ground is at Vcc/2.
When a single supply is used a Vcc/ 2 point is created with two equal resistors (and a cap).

 

[stratus46]

I was tired and i thought they werent needed and i wanted to see how it sounded,it took me 2 hours to solder all that crap in cause my soldering iron sucks and i never used perfboard

Helpful hint: When a manufacturer says parts are optional they can be safely omitted but don't make changes unless you fully understand.

G²

 

[PetruV]

Helpful hint: When a manufacturer says parts are optional they can be safely omitted but don't make changes unless you fully understand.

G²

I udestood it but i did the modification that was marked in red and it now works

 

[PetruV]

Now works did the scematic as in the image and adding the componets in red

 

[PetruV]

It broke,it makes a lot of sounds even when its not hoked up to my pc,i think it starts to oscilate making a very loud noise

 

[PetruV]

I think the chip is dead it makes a very loud thinking noise even when its not hooked up to my computer,when i conect it to my computer the noise still continues and distorts the music

 

[picowallspeaker]

I wouldn't use those ceramic capacitors . They are good for suppressing HF noise on the supply line, and they do the same duty well for reducing bandwidth at input (LP filter) of amplifier .
Use plastic dielectric ones...polyester, styrene, ecc for a Vl of 63-100 V.

 

[PetruV]

I wouldn't use those ceramic capacitors . They are good for suppressing HF noise on the supply line, and they do the same duty well for reducing bandwidth at input (LP filter) of amplifier .
Use plastic dielectric ones...polyester, styrene, ecc for a Vl of 63-100 V.

Oh thats why it sounded not bassy when it worked!

 

[PetruV]

Can someone post a good schematic here,with not a lot of components and mostly with the components that are on the schematic just swaped around

 

[bobodioulasso]

http://www.ti.com/lit/ds/symlink/lm1875.pdf

 

[PetruV]

I think il use danielwritesbac veroboard version,but my soldering iron burned up since i worked too much with it since i was desperate to her the amp,in coupe minutes il go to the shop with my dad and i will return most probably succesfull in one hour

 

[PetruV]

got a new soldering iron and its so good wow,much better than my old one

 

[picowallspeaker]

You can raise the value of the input capacitor .
That will increase bass . 1 till 3 uF are ok

 

[PetruV]

This is the schematic im building now,i got a new soldering iron and its so awesome!1!!1

 

[bobodioulasso]

This one is now symmetrical supply.