Stereo Amplifier project help !!

Discussion in 'The Projects Forum' started by vikru_2008, Mar 10, 2012.

  1. vikru_2008

    Thread Starter New Member

    Mar 10, 2012
    10
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    i've been working on my stereo amplifier project using BA5406 power amplifier..
    the supply required is about 12V ,1.5 amp dc. I am using a regulated dc power supply for that....i assembled the circuit and adjusted 12v,1.5 amp on the power supply ..but as soon as i connect the supply to my circuit ,the supply voltage got reduced to below 5V and i am unable to increase the voltage beyond 4.5 volt..i need help with this ASAP ..i have to submit my project in 4 days time ..i've not yet assembled the project.. i m testing it on the breadboard.. the circuit diagram for my project is shown in this link

    http://www.quasarelectronics.com/kit-files/electronic-kit/3090h.pdf
     
  2. vikru_2008

    Thread Starter New Member

    Mar 10, 2012
    10
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    BUMP.....................
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,011
    3,233
    Sounds like a wiring error. Have you double-checked all your component connections and capacitor polarities?
     
  4. roadey_carl

    Active Member

    Jun 5, 2009
    116
    5
    post a pic of the circuit you have made! also if the voltage is dropping right down then something is pulling too much current... like crutschow said, check wiring and polarity of capacitors!
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    An audio amplifier iC like that old obsolete one (amplifier for a cassette tape player?)oscillates at a high frequency and uses a lot of power supply power when it is made on a breadboard. You are supposed to build it on a compact pcb using the manufacturer's suggested layout as shown on its datasheet.
     
  6. mateenyasin1

    New Member

    Mar 20, 2012
    6
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    Well i would say it would be cuz of the incorrect polarity of capacitors :p
     
  7. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    If you are drawing enough current to collapse the power supply rail, something should get hot to the touch.
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,047
    ...unless there's something wrong with the power supply, so that the voltage is collapsing at currents far below the 1.5A spec. Maybe there's nothing wrong with your amplifier.

    Have you measured current draw when you hook it up? Can the power supply light a 12V light bulb such as an automotive tail light?
     
  9. vikru_2008

    Thread Starter New Member

    Mar 10, 2012
    10
    0
    i've mounted the entire circuit on pcb now..tried using regulated power supply, 12v-1 A dc adapter still the problem persists.. the supply voltage is getting dropped from 12v to 4 v
    i checked the connection many times.. can u find any problem with the circuit?
    http://www.quasarelectronics.com/kit...-kit/3090h.pdf
     
  10. vikru_2008

    Thread Starter New Member

    Mar 10, 2012
    10
    0
    ya ..the power supply is working fine...i even tried using a regulated dc supply.. but having the same problem...can u find anything wrong with this circuit?
    http://www.quasarelectronics.com/kit...-kit/3090h.pdf
     
  11. vikru_2008

    Thread Starter New Member

    Mar 10, 2012
    10
    0
    yea i check all connections ..its same as shown in this ckt ..http://www.quasarelectronics.com/kit...-kit/3090h.pdf
    is there any problem with the circuit?
     
  12. vikru_2008

    Thread Starter New Member

    Mar 10, 2012
    10
    0
    i 've made the pcb layout using the same ckt as shown in the link http://www.quasarelectronics.com/kit...-kit/3090h.pdf
    the polarities are also correct..i dont know still why the ckt aint working?
    btw can anyone plz tell me what the exact reason behind supply voltage drop is ?
    i guess that wud give me some kind of solution ..
     
  13. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The amplifier IC made by Rohm has a serious error on the schematic of the IC in its datasheet. It shows the bootstrap capacitors pin 3 and pin 10 shorted to the positive power supply pin 1.
    If Rohm makes mistakes on the datasheet schematics of their ICs (SHAME on them) then maybe there are more mistakes in the IC.

    The schematic for the kit uses European Text (2R2) for the values of the 2.2 ohm resistors at the outputs of the amplifier IC.

    The schematic for the kit is missing very important one 0.1uF ceramic disc and one 100uF (or more) electrolytic supply bypass capacitors on the circuit board that keep the amplifier IC from oscillating.

    The amplifier has very high voltage gain and is non-inverting so it will oscillate if the input wiring is near the output wiring.

    Maybe your IC is counterfeit or is blown up?
     
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