Stereo Amplifier project help !!

Thread Starter

vikru_2008

Joined Mar 10, 2012
10
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
 

roadey_carl

Joined Jun 5, 2009
134
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!
 

Audioguru

Joined Dec 20, 2007
11,249
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.
 

wayneh

Joined Sep 9, 2010
16,384
...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?
 

Thread Starter

vikru_2008

Joined Mar 10, 2012
10
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.
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
 

Thread Starter

vikru_2008

Joined Mar 10, 2012
10
...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?
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
 

Audioguru

Joined Dec 20, 2007
11,249
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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