I have trouble uderstanding the power supply of one amp. I have disconnected the the supply from the audio amp section and then I connected an external supply to the audio amp and it worked just fine. Checks in the power supply include the MOSFETs, transformer, schottkey barrier rectifiers, filter capacitors and coils as well as the pulsewidth modulator IC.

The power supply just won't work. I have checked all solder joints. The protection feedback circuitry from the audio...

A: Look up the data sheets for the components and use a multi-meter to see if the components are within tolerances.

This will invlove removing each component for individual testing. Be careful with the double sided circuit board and the static sensistive MOSFETs.

This is for a portable speaker system, I need to use the two amps because the 1 amp overheats with the 9.6 volt battery. have a 9.6 volt battery supply and 2 portable amps that normally take 4 AA batteries. The battery I am using is a rechargable ni-cad. thanks.

A: You need to connect them the way that gets you the correct voltage for your amp. A series battery connection adds the voltages - a parallel connection keeps the voltage the same (you get twice the current capability though).

It might be a good idea to buy a cheap multimeter if you are going to experiment with stuff like this.

http://www.radioshack.com/product/index.jsp?productId=2103174

I'm trying to get info on the best sounding car amps.

A: This may help with some things (not reviews, but choosing type): http://spkrbox1.spaces.live.com

Overview

The circuit has been designed to produce an audio amplifier that can be used for low efficiency speakers or outdoor sound systems since it can deliver 300W of power.

TerminologyPower Amplifier – a type of amplifier built and designed for the purpose of delivering and supplying sufficient and maximum high output power to directly drive loudspeakers or loads, within a given percent of distortionBC547 – NPN small signal transistors designed for general purpose switching and amplification due to its low voltage, low current and three different gain selectionsMJ15003 – a ballasted epitaxial-base silicon NPN high power transistor used for series and shunt regulators, solenoid drivers, power switching circuits, high-fidelity amplifiers, and other industrial and commercial use due to its features such as high gain at high current, maximum safe-area-of-operation curves, low saturation voltages, rugged design, and high dissipation capabilityCircuit Explanation

The construction of the circuit consists of three parts which includes the input stage, the power stage, and the power supply. The input stage produces the high gain as it functions as the low power driver while it comprises of transistors Q1 to Q9 while the output stage provides massive power gain although it only has a voltage gain of four. The input stage has its own current source in each side as it functions as a complementary differential network. A collector current of approximately 0.7 mA is used to run the transistors at the input stage. The improvement of linearity and gain stabilization is done by the emitter resistors.

The transistors Q7 & Q9 are virtually two constant-current sources that conducts at 7 mA and is driven by the output of Q1-Q5. An out of phase modulation is performed by these virtual current sources during an input signal, where the collector current of one decreases while the other increases. A sufficient amount of gain is provided by this configuration.

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