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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

Audio Amplifier


Audio Amplifier
The principal component of the amplifier kit is the LM 386 IC. This IC is specifically designed as a low wattage amplifier for small scale projects. The signal enters through R1, the 10Kohm potentiometer. This also serves as a volume control for the circuit. The signal is introduced to pin 3 of the IC.
The amplifier output is passed directly to speaker through C2. The capacitor is used to isolate the speaker from the dc power that drives the amplifier.

The circuit composed of R2, the 1K ohm resistor, and C1 the 10uF capacitor, establishes the gain of the amplifier. For this circuit, the gain is set at 50.To increase the gain you can either increase the value of the capacitor or decrease the value of the resistor.

The 0.uF capacitor placed across the power source is used to eliminate noise that can be generated by power source.