Mini-MosFet Audio Amplifier

Power Amplifier Circuit diagram:

Power Amplifier Parts:

R1_______________2K2 1/4W Resistor
R2______________27K  1/4W Resistor
R3,R4____________2K2 1/2W Trimmers Cermet or Carbon (or 2K)
R5_____________100R  1/4W Resistor
R6_______________1K  1/4W Resistor
R7,R8__________330R  1/4W Resistors

C1______________22µF  25V Electrolytic Capacitor
C2______________47pF  63V Polystyrene or Ceramic Capacitor
C3,C4__________100µF  50V Electrolytic Capacitors
C5____________2200µF  50V Electrolytic Capacitor

Q1____________BC550C  45V 100mA Low noise High gain NPN Transistor
Q2___________IRF530  100V 14A N-Channel Hexfet Transistor (or MTP12N10)
Q3__________IRF9530  100V 12A P-Channel Hexfet Transistor (or MTP12P10)

This project was a sort of challenge: designing an audio amplifier capable of delivering a decent output power with a minimum parts count, without sacrificing quality.
The Power Amplifier section employs only three transistors and a handful of resistors and capacitors in a shunt feedback configuration but can deliver more than 18W into 8 Ohm with <0.08% THD @ 1KHz at the onset of clipping (0.04% @ 1W - 1KHz and 0.02% @ 1W - 10KHz) and up to 30W into a 4 Ohm load.
To obtain such a performance and to ensure overall stability of this very simple circuitry, a suitable regulated dc power supply is mandatory. This is not a snag because it also helps in keeping noise and hum of the preamp to very low levels and guarantees a predictable output power into different load impedances. Finally, as the amplifier requires only a single rail supply, a very good dc voltage regulator capable of supplying more than 2 Amps @ 40V can be implemented with a few parts also.

Setting up the Power Amplifier:

The setup of this amplifier must be done carefully and with no haste:

1. Connect the Power Supply Unit (previously tested separately) to the Power Amplifier but not the Preamp: the input of the Power Amplifier must be left open.
2. Rotate the cursor of R4 fully towards Q1 Collector.
3. Set the cursor of R3 to about the middle of its travel.
4. Connect a suitable loudspeaker or a 8 Ohm 20W resistor to the amplifier output.
5. Connect a Multimeter, set to measure about 50V fsd, across the positive end of C5 and the negative ground.
6. Switch on the supply and rotate R3 very slowly in order to read about 23V on the Multimeter display.
7. Switch off the supply, disconnect the Multimeter and reconnect it, set to measure at least 1Amp fsd, in series to the positive supply (the possible use of a second Multimeter in this place will be very welcomed).
8. Switch on the supply and rotate R4 very slowly until a reading of about 120mA is displayed.

Preamp Circuit diagram:

Preamp Parts:

P1______________50K  Log. Potentiometer (or 47K)
                     (twin concentric-spindle dual gang for stereo)
P2,P3__________100K  Linear Potentiometers
                     (twin concentric-spindle dual gang for stereo)

R1_____________220K  1/4W Resistor
R2_____________100K  1/4W Resistor
R3_______________2K7 1/4W Resistor
R4,R5____________8K2 1/4W Resistors
R6_______________4K7 1/4W Resistor
R7,R8,R13________2K2 1/4W Resistors
R9_______________2M2 1/4W Resistor
R10,R11_________47K  1/4W Resistor
R12_____________33K  1/4W Resistor
R14____________470R  1/4W Resistor
R15_____________10K  1/4W Resistor
R16______________3K3 1/4W Resistor (See Notes)

C1,C2,C9_______470nF  63V Polyester Capacitors
C3,C4___________47nF  63V Polyester Capacitors
C5,C6____________6n8  63V Polyester Capacitors
C7______________10µF  63V Electrolytic Capacitor
C8,C10__________22µF  25V Electrolytic Capacitors
C11____________470µF  25V Electrolytic Capacitor (See Notes)

Q1,Q3_________BC550C  45V 100mA Low noise High gain NPN Transistors
Q2___________2N3819   General-purpose N-Channel FET

1. Check again the voltage at the positive end of C5 and readjust R3 if necessary.
2. If R3 was readjusted, R4 will surely require some readjustment.
3. Wait about 15 minutes, watch if the current is varying and readjust if necessary.
4. Please note that R3 and R4 are very sensitive: very small movements will cause rather high voltage or current variations, so be careful.
5. Those lucky enough to reach an oscilloscope and a 1KHz sine wave generator, can drive the amplifier to the maximum output power and adjust R3 in order to obtain a symmetrical clipping of the sine wave displayed.

The Preamp sensitivity and overload margin were designed to cope with most modern music programme sources like CD players, Tape recorders, iPods, Computer audio outputs, Tuners etc. The source selecting switches and input connectors are not shown and their number and arrangement are left to the constructor's choice.
To obtain a very high input overload margin, the volume control was placed at the preamp input. After a unity gain, impedance converter stage (Q1) a negative-feedback Baxandall-type Bass and Treble tone control stage was added. As this stage must provide some gain (about 5.6 times) a very low noise, "bootstrapped" two-transistors circuitry with FET-input was implemented. This stage features also excellent THD figures up to 4V RMS output and a low output impedance, necessary to drive properly the Mini-MosFet Power Amplifier, but can also be used for other purposes.

Regulated Power Supply Circuit diagram:

Regulated Power Supply Parts:

R1_______________3R9 1 or 2W Resistor
R2______________22R  1/4W Resistor
R3_______________6K8 1/4W Resistor
R4_____________220R  1/4W Resistor
R5_______________4K7 1/2W Resistor

C1____________3300µF  50V Electrolytic Capacitor (or 4700µF 50V)
C2,C5__________100nF  63V Polyester Capacitors
C3______________10µF  63V Electrolytic Capacitor
C4_____________220µF  50V Electrolytic Capacitor

D1_____Diode bridge  100V 4A 
D2___________1N4002  200V 1A Diode
D3______________LED  Any type and color

IC1___________LM317T 3-Terminal Adjustable Regulator

Q1____________TIP42A  60V 6A PNP Transistor

SW2_____________SPST  Mains switch

T1_____________230V Primary, 35-36V (Center-tapped) Secondary,
                    50-75VA Mains transformer (See Notes)

PL1____________Male Mains plug with cord

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Comments:

A very good and powerful Regulated Power Supply section was implemented by simply adding a PNP power transistor to the excellent LM317T adjustable regulator chip. In this way this circuit was able to deliver much more than the power required to drive two Mini-MosFet amplifiers to full output (at least 2Amp @ 40V into 4 Ohm load) without any appreciable effort.

Notes:

• Q2 and Q3 in the Power Amplifier must be mounted each on a finned heatsink of at least 80x40x25mm.
• Q1 and IC1 in the Regulated Power Supply must be mounted on a finned heatsink of at least 45x40x17mm.
• A power Transformer having a secondary winding rated at 35 - 36V and 50VA (i.e. about 1.4Amp) is required if you intend to use Loudspeaker cabinets of 8 Ohm nominal impedance. To drive 4 Ohm loads at high power levels, a 70 - 75VA Transformer (2Amp at least) will be a better choice. These transformers are usually center tapped: the central lead will be obviously left open.
• For the stereo version of this project, R16 and C11 in the Preamp will be in common to both channels: therefore, only one item each is necessary. In this case, R16 must be a 1K5 1/2W resistor. The value of C11 will remain unchanged.

Audio Car Design

A stock car audio system refers to the Original equipment manufacturer (OEM) application that the vehicle's manufacturer specified to be installed when the car was built. A large after market industry exists where the consumer can at their desire replace many or all components of the stock system. In modern cars, the primary control device for an audio system is commonly referred to as a head unit, and is installed in the center of the dash panel between the driver and the passenger. In older vehicles that had audio components as an option, such devices were mounted externally to the top of or underneath the dash. Car speakers often use space-saving designs such as mounting a tweeter directly over a woofer or using non-circular cone shapes. Subwoofers are a specific type of loudspeaker for low frequency reproduction. Extremely loud sound systems in automobiles, which have been nicknamed "boom cars", may violate the noise ordinance of some municipalities.

Audio Car Design

Upgrade Car Audio Speakers First

There's nothing quite like the sweet sound of your favorite music coming clearly through your car's audio system. Unfortunately, the stock speakers in most older or inexpensive cars really are nothing quite like that. Unless you happen to get a new car with expensive factory audio upgrade, you're forced to listen to tinny, crackling distortions that drive any music lover nuts.

To get a complete stereo system upgrade worth paying for, you normally need to spend a few thousand dollars to replace everything from the head unit, the power wiring, speaker wires and speakers. And of course you would be adding aftermarket amplifiers, speaker enclosures and other accessories. That's a big project and a large bill to pay all at once.

There is some good news though. You can get a huge improvement in sound just by replacing the factory speakers that came with your car. The cheap speakers that come with most cars are made with the lowest quality material and construction methods to keep the costs down. You will typically find weak paper cones, poor wiring, and brittle glue holding it all together. These materials degrade quickly after much use since an audio speaker is really a moving part in your car, but the cheap ones are not very mechanically sound.

Even inexpensive aftermarket speakers will sound better than these. At the lowest end, an aftermarket speaker will have better quality cones, domes, and wiring. Paper may still be used in the cones and domes, but it will be treated and stiffened to provide better sound quality and more durability.

If you can spend a little more money, you can get into some more exotic materials such as carbon fiber or specially designed plastics. This type of speaker will give you even more range, durability, and have a higher threshold for power if you choose to add amplifiers to your system down the road.

Going up one more step, you can get speakers designed for stock speaker replacement that will have a special configuration that puts two speakers, typically a mid-range and tweeter, into the same space as a single speaker. And if you have a compatible vehicle, you can even get tweeter and mid-range speaker kits that have the tweeter in a separate enclosure for you place in an appropriate spot in your car.

It may seem like overkill to spend much money putting good speakers into your car without replacing the tuner or adding amps, but you will notice a big improvement with just this one change, and it paves the way to upgrading your system incrementally. By replacing the speakers first, you're able to enjoy better sound immediately while you take the time upgrade the rest of your system.

Reviews 2010 KIA Forte

The brand-new Kia Forte Koup is Kia's first two-door coupe and a sibling to the new Forte sedan, Which is Kia's replacement for its sad-sack Spectra and its answer to cars like the Honda Civic, the Toyota Corolla, and the Mazda3 . The "Koup" moniker is a melding of the "K" from "Kia" and the "OUP" from "coupe." The Forte Koup Will Be at Kia dealers by August or September.

The Kia Forte Koup's fresh, modern styling is definitely a strong point. Along with the Forte sedan, it represents a new design direction for Kia, Which is making a big effort to distinguish its products Visually from corporate parent Hyundai's. The Koup's mesh grille and air intake are part of a new Kia family signature look That you'll see on more cars in the future. A strong shoulder line running the length of the car and the standard 16-inch or optional 17-inch alloy wheels give the Koup a sharp street stance.

We drove two examples of the upper trim levels, the SX; one with a manual transmission and black cloth upholstery, the other with an automatic and black leather. Both Had Some sporty front seats with red stitching and bolstering. The overall cabin design is pleasing, and the build quality is very good. The interior plastics are a little hard to the touch but largely inoffensive. The driver's door armrest needs more padding. The center stack is well-particularly Designed and finished with a glossy black material. Stereo and HVAC controls are logical, and a superb six-speaker CD stereo with iPod/MP3 connectivity is standard. The SX's substantial dead pedal (on the far left of the driver's footwell, for resting your left foot Pls it's not on the clutch) is finished in polished metal like the other pedals.

KIA CAR FORTE

The base is equipped EX Koup with a 2.0-liter four-cylinder engine producing 156 hp and 144 lb-ft of torque, while the SX gets a Bigger, 2.4-liter four That bumps up to 173 hp and torque to 168 lb-ft . The Smaller engine is mated to a standard five-speed manual transmission or an optional four-speed automatic, while the 2.4-liter SX gets a six-speed manual as standard and an optional five-speed automatic. These mirrors powertrains Those of the Forte sedan; Forte both models are front-wheel-drive vehicles. EX Both models are rated at 25/34 city / highway EPA fuel economy. The more powerful SX is rated at 22/32 with the manual, 23/31 with the automatic.

The Forte Koup has a strut-type front suspension with coil springs, typical in this class of car, but it makes do with a beam-axle rear suspension, a technical detail That definitely falls short of cars like the Honda Civic and Mazda 3, Which have independent rear suspensions. Over smooth road surfaces, you'll never notice or care, but the going gets rough Pls, stiff springs and the beam axle conspire to send the rear end skittering sideways. Front and rear anti-roll bars are standard.

Overall, the Forte Koup driving meets the standards of this class of car. Body roll is reasonably well-contained, the steering has Some feel to it, if it's a little dead on-center, and there's a distinct lack of the sponginess in chassis and suspension That characterized previous models like the Kia Spectra. Our limited drive in Seoul, South Korea, from Kia's headquarters up to the DMZ was entirely During a major rainstorm, so We have had no opportunity to drive the car on dry pavement. It's fairly clear, though, that although the Kia Forte Koup is no sports car, it's got spirit Enough to keep most drivers happy.

Electronics Circuit Diagram

The following schematic illustrates the simple Audio Level Controller Circuit Diagram designed and produced by SHURE microphones and electronics components. All the capacitors in MFD unless shown otherwise and working voltages over 100 unless shown. All resistors 10% tolerance. The selected resistor is chosen to adjust point where regulating action starts to corresponds to distance selector switch settings.

SHURE Model M62 Audio Level Controller Circuit Diagram