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Car Mini-MosFet Audio Amplifier Circuit

2015-01-06 03:27  
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The circuitmust haveanappropriate DCpower supply.This helpsthepreamplifiernoise andhumto verylow levels,to ensurea predictableoutput powerinto differentload impedances.With theamplifierrequires onlyasingle railsupply,avery gooddcvoltage regulatorcan providemore than 2 Amps@ 40 vcan achieveseveral partsalso.Despite thepower amplifier sectionof the circuitemploying onlythreetransistorsand a fewresistors and capacitorsin ashunt feedbackconfigurationbut can bedelivered more than18 winto 8 ohmsand<0.08%@ 1 khzconsistent withthe onsetofclipping(0.04% @ 1 w - 1khzand0.02% @ 1 w - 10 khz)and30 winto a 4ohm load.The amplifier isconnected tothe powersupply unit(before thetest, respectively)to the power amplifier, but notpre-amplifier: Inputpower amplifiermust beopen.Connectasuitableloudspeakeror 8ohm20 wresistoramplifieroutput.R3 andR4are very sensitive:very smallmovementwill causea relatively highvoltage orcurrent changes,so be careful.

Mini MosFet Power Amplifier

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)
Preamp Circuit diagram:In a unity gain, impedance converter stage (Q1) a negative feedback bass and treble, "added the fifteenth century type tone control phase. As at this stage to provide some gain (approximately 5.6 times) a very low noise, "self" two input transistors and field-effect transistor circuit implementation. This stage features also excellent tensile data up to 4 v RMS output and a low output impedance, necessary for the correct driving mini mosfet power amplifier.Preamp for the Mini-MosFet Amplifier

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

The circuit by simply adding a PNP power transistors excellent LM317T  adjustable regulator chip to achieve a robust power supply section. So that this circuit can provide more energy than needed to drive two mini mosfet amplifier output completely (at least 2 Amps @ 40 v 4 ohm load) without any apparent effort. Q1 and IC1 in the power supply must be installed in a finned radiator x40x17mm at least 45. Stereo version of this item, the preamplifier R16 "are given in the common channel and C11: thus, only one each of which is necessary in this case, must be 1 for R16" is given in 1 / 2W resistors. Values ??remain unchanged C11.

Regulated Power Supply for the Mini-MosFet Amplifier

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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