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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of

45 Watt Class B Amplifier

 

Parts:

 
R1______________18K  1/4W Resistor
R2_______________3K9 1/4W Resistor
R3,R6____________1K 1/4W Resistors
R4_______________2K2 1/4W Resistor
R5______________15K 1/4W Resistor
R7______________22K 1/4W Resistor
R8_____________330R 1/4W Resistor
R9,R10__________10R 1/4W Resistors
R11,R12_________47R 1/4W Resistors
R13_____________10R 1W Resistor


C1_______________1µF 63V Polyester Capacitor
C2_____________470pF 63V Polystyrene or Ceramic Capacitor
C3______________47µF 25V Electrolytic Capacitor
C4______________15pF 63V Polystyrene or Ceramic Capacitor
C5_____________220nF 100V Polyester Capacitor
C6_____________100nF 63V Polyester Capacitor

D1,D2,D3,D4___1N4148 75V 150mA Diodes

Q1,Q2________BC560C 45V 100mA Low noise High gain PNP Transistors
Q3,Q4________BC556 65V 100mA PNP Transistors
Q5___________BC546 65V 100mA NPN Transistor
Q6___________BD139 80V 1.5A NPN Transistor
Q7___________BD140 80V 1.5A PNP Transistor
Q8__________MJ2955 60V 15A PNP Transistor
Q9__________2N3055 60V 15A NPN Transistor
 
 
 

Power supply circuit diagram:

 

Parts:

R1_______________3K3  1/2W Resistor

C1,C2_________4700µF 50V Electrolytic Capacitors
C3,C4__________100nF 63V Polyester Capacitors

D1_____________200V 8A Diode bridge
D2_____________5mm. Red LED

F1,F2__________4A Fuses with sockets

T1_____________230V or 115V Primary, 25+25V Secondary 120VA Mains transformer

PL1____________Male Mains plug

SW1____________SPST Mains switch

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