DIY...Electronic...Repair...Amplifier.

DIY...Electronic...Repair...Amplifier.

How to add power supply filter capacitor to amplifier board.

I saw a new comment on my video, he asked me how to add a filter capacitor to amplifier board D.C. power supply. I think it's a good question so I will explain it here.


What is a power supply filter capacitor?

It is the capacitor that used to filter AC ripple from DC power supply present to amplifier board. If an amplifier has low capacitive power supply capacitor, it may present a little hum(50/60 Hz low-frequency sound) that you can hear in a quiet room.

The capacitor also stores power and bring it instantly to your amplifier when an amplifier needs more power for a short period of time such as  explosion sound in a movie.

However, If an amplifier has high-frequency power supply noise from a switching power supply, small capacitor need to parallel to a power supply and must be attached close to power amplifier IC as much as possible.

Below pictures are the place that you add power supply capacitor.

TA 2024 board amplifier power supply connection


PAM 8610 board amplifier power supply sign

Caution!! an electrolytic capacitor has polarity. DO NOT REVERSE BECAUSE IT CAN BE EXPLODE OR CAUSE A FIRE!!!

An image below shows capacitor polarity.























Below is the formula for DC smoothing capacitor

C = I x t/ΔV

C = capacitance in Farad (multiply 1,000,000 and you get uf value)
I = power supply ampere
t = time that capacitor supply current to load for 1/2 cycle
(8.3 ms for 60 Hz and 10 ms for 50 Hz 220 volts line)
ΔV = voltage drop while current flowing out from capacitor

example:
pam 8403 give 10 watts power @ 4 ohms that mean it consumes around 2 Amps at full power (add 10% for any lost in amplifier)so, I =2.2 amps

t 0.008 for 60 Hz AC line

ΔV = maximum voltage drop when current flow from capacitor to load = 1 volt max

C = 2 x 0.008 / 1

C = 0.016 Farad

Convert to uf = 0.016 x 1000000

C = 16,000 uf and that makes the caps bigger than amp board and you don't need it because in real life you don't need full clean DC for Pam 8403 to operate, you just need 1 / 100 for instant transient peak music so 160 uf is enough but commercial capacitor value is 100 uf or 220 uf so I pick 220 uf as minimum value.


See more tutorial.

HOW TO MAKE A DC POWER SUPPLY FOR YOUR AMPLIFIER




Enjoy electronic hobby with EASYANDWORKPROJECT.XYZ

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7/11/16, 6:37 AM ×

thanks for clear explanation

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12/6/16, 10:44 PM ×

I have D-amplifier that whenever I touch the volume knob it produces hum. Will this be helped by capacitor on powerinput?, aluminum casing? thanks

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12/7/16, 8:41 PM ×

Try ground potentiometer case to ground and see the result :D

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12/8/16, 2:37 AM ×

Thanks, that was the problem....

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Jacks Ace
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5/7/17, 8:37 PM ×

Any specific value for the farad?or just pick random value?i have pam8403

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5/7/17, 10:19 PM ×

For pam 8403 you need at least 220 uf to 2200 uf and you are free of hum.
I made so many amplifier and that is real life experience.
However, if you need formular.

C = I x t/ΔV

C = capacitance in Farad (multiply 1,000,000 and you get uf value)
I = power supply ampere
t = time that capacitor supply current to load for 1/2 cycle
(8.3 ms for 60 Hz and 10 ms for 50 Hz 220 volts line)
ΔV = voltage drop while current flowing out from capacitor

example:
pam 8403 give 10 watts power @ 4 ohms that mean it consumes around 2 Amps at full power (add 10% for any lost in amplifier)so, I =2.2 amps

t 0.008 for 60 Hz AC line

ΔV = maximum voltage drop when current flow from capacitor to load = 1 volt max

C = 2 x 0.008 / 1

C = 0.016 Farad

Convert to uf = 0.016 x 1000000

C = 16,000 uf and that makes the caps bigger than amp board and you don't need it because in real life you don't need full clean DC for Pam 8403 to operate, you just need 1 / 100 for instant transient peak music so 160 uf is enough but commercial capacitor value is 100 uf or 220 uf so I pick 220 uf as minimum value.

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Jacks Ace
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5/8/17, 3:58 PM ×

well described..thanks a lot for this info

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6/26/17, 11:27 PM ×

❓CAN I REPLACE SMD CAPACITORS FROM PAM8403 AMPLIFIER BOARD❓ SUDDENLY IT NOT WORKING, BUT IC GETTING HOT AFTER POWER CONNECT.... PLEASE ANSWER...

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10/20/17, 6:27 PM ×

Hello!
Can i solder power supply cap downside the pcb board?
Thank you!

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10/22/17, 4:27 AM ×

Thank you!

The first small caps near amp input they are decoupling caps?
in my version they are 1uf

I changed them to Vishay Ero 1818 mkt 1uf 63v

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10/22/17, 4:39 AM ×

i tried with supply cap and its working very nice
nothing- completly black background. But i soldered 6800 uf cap
I think its ok with this big cap for power supply?

Thanks a lot!

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10/22/17, 5:07 AM ×

No, I think decoupling- they are first to power input (first to the speakers terminal)

So, tell me Phethai abot small 1 uf caps please... :)

Regards!!!!

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10/22/17, 9:50 PM ×

It's ok to use 6800 uf cap for power supply. The bigger cap the better smooth DC current.

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10/22/17, 9:52 PM ×

Did you mean 1 uf from TA2024 or pam8610 board?

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10/22/17, 10:13 PM ×

Thank you Phethai for feedback

I mean front 1uf or in some versions bipolar elna blue 2.2uf caps at the front of ta2024

close to the pin's input.

This big cap working fine! But i wanted to be sure, and I also trust in your electro-wisdom.

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