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Removing Noise in amplifier circuit

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vikky

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Sir,

I have designed a circuit to play music but as i increase the volume the noise also increases.I have attached the circuit.Pls advise me how 2 reduce the noise and increase the sound volume.

Thank You.
 

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jabberwocky_one

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What is the Wattage Rating for speaker ? How many watts do you intend to drive it to ? Will the LM386 able to handle the wattage at its output pin ?

VCC_ARROW, how many volts is that ? +12V/+3V/+5V ?

By noise, do you mean blarring like trumpets(distortion) or hissing ?
 
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muthukumar_ece2004

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Hi, how do you try this circuit either in bread board or perf board or PCB?

If you are using bread board or perf board means you have to provide proper isolation for the audio signal, you should need to provide ground connection over the board.
There is nothing to say the correction on circuit. You need to correct your way of approaching the circuit board. You must consider the isolation for the audio signal. If you
are using PCB means, there is no more consideration.
 

vikky

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Thank you jabberwocky_one and muthukumar_ece2004 for your kind response.

@muthukumar_ece2004

Sir,
I am doing it on PCB and speaker connection is located below LM386.

@jabberwocky_one

Sir,
Rating for speaker is .5W and 8ohms.VCC_ARROW is +5V.Input to AP89010(Voice IC) is 3.3V.there is hissing sound when volume increases.Will a transistor solve the problem.if so where shud i place it?

Thank u

Vikky
 

jabberwocky_one

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What is the purpose of R3, 368ohms ?
Wouldn't that force the volume control to be very loud ?

Where is your +5V coming from ? Perhaps adding a bypass capacitor if the source has ripple ?

A very lousy and cheap method to reduce noise on your output would be adding resistors in series with the speaker. (This also reduces volume output)
Value range: >50 ohm.

I just noticed that the AP89010 has a VOUT1 and VOUT2 that can be hooked directly to speakers.
Sorry, but if you dont mind me asking, why an amplifier is needed when the AP89010 can directly drive the speakers ?
 
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vikky

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What is the purpose of R3, 368ohms ?
Wouldn't that force the volume control to be very loud ?

Where is your +5V coming from ? Perhaps adding a bypass capacitor if the source has ripple ?

A very lousy and cheap method to reduce noise on your output would be adding resistors in series with the speaker. (This also reduces volume output)
Value range: >50 ohm.

I just noticed that the AP89010 has a VOUT1 and VOUT2 that can be hooked directly to speakers.
Sorry, but if you dont mind me asking, why an amplifier is needed when the AP89010 can directly drive the speakers ?
Thank you Sir.I tried connecting the capacitor and i am getting much better tempo.I connected 100uF.but still some noise is left.i do feel a transistor can do the trick.What do u feel?
I dont want 2 reduce the volume so i didnt try the speaker part.
If i gave it directly from AP89010 i will not get the desired volume so went for amplification.
 

jabberwocky_one

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Sorry, my knowledge only takes me up to this point.
Someone kindly take over.
 

BradtheRad

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1.

I've heard a few sounds from synthesizer chips. They seem to have white noise built into them. Because while the sound is playing I can hear white noise at the same time.

Is the synthesizer chip creating sound even when you're not playing a tone? Then it may be the source of the noise.

2.

There are such things as noisy transistors and noisy capacitors. There are even noisy resistors.

Particularly in the case of an aging electrolytic capacitor, it may inject continuous pops and crackles into an audio signal. The only solution is to replace the capacitor.
 

jabberwocky_one

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Now that you mentioned noise coming from synth chips, I've checked the datasheet for the AP89010 and I think he's running it out of spec for the Osc function (R4).
Datasheet here Page 15 Oscillator Table only states up to 25 kHz with a 43 kOhm resistor.
I don't see any maximum nor minimum rating for the Osc function so if the table's final item is assumed max then yeah he's running it out of spec.
 
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snirts

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Sir,

I have designed a circuit to play music but as i increase the volume the noise also increases.I have attached the circuit.Pls advise me how 2 reduce the noise and increase the sound volume.

Thank You.
just simply add big bvalue of capacitor that you use,..
 

elekrtonikel

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@vikky
you must add a blocking capacitor as near as possible between pin 12 and pin 4 of U2 to stabilize VCC. Capacity minimum .1µF , better 1µF tantalium type. Otherwise the U2 may produce radio frequencies in the background.
 

rimidub

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Sir,

I have designed a circuit to play music but as i increase the volume the noise also increases.I have attached the circuit.Pls advise me how 2 reduce the noise and increase the sound volume.

Thank You.
You should consider this: potentiometer which you use has it's internal resisttance, which is low for low level (counter clockwise position) and for high level (clockwise position). Worst case is when your potentiometer is in the center position, because then the current (bias current of the input) flowing through creates noise. You should use potentiometer with lower resistance (e.g.5..10Kohm), or try inserting capacitor in series with the output of the potentiometer. Potentiometer should be either mounted on the PCB or connected with shielded cables (coaxial).

Best regards
 

Syncopator

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vikky,

Disconnect the AP89010 and ignore it for now. Get the amplifier working satisfactorily first.

Only then reconnect the AP89010 and proceed from there.
 

BradtheRad

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This suggestion may not apply because your schematic shows you're running the amplifier at low gain.

However if you were running at high gain then you would need to reduce your incoming signal to a tiny fraction. Then whatever amount of white noise is generated in the amplifier, it will be at a greatly increased proportion, compared to the music.
 

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