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

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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
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Automatic Room light and fan control with visitor counting

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This system will control the room light and fan by taking inputs as person count, room light intensity and room temperature.

Working:  When there is no person entered in to room then person count will become zero and then it will not check intensity and temperature, so that bulb and fan will be in OFF mode.  If a person enters into a room then the person count will be increased by '1' and if person exits a room then person count will decrease. If person count is greater than zero then it will check intensity and temperature. If the room intensity is less than the threshold then the bulb will glow otherwise will be in OFF mode only and if the room temperature exceeds the threshold temperature then the fan will start moving otherwise will be in OFF mode only.

Pictorial view of system arrangement 
  
  to download C-code
  to see its working video-1
to see working video-2

Here is the main flow chart


 
This flow chart is used to indicate person count, but in practical we dont need to implement this part

 Output Results:
case'1': when there is no person in the room
LEDs showing count value is '0'

case'2': when there are two persons in the room, room condition the intensity is less and temperature is greater than the threshold temperature


                       
NOTE:
1. Threshold values may be different in practical 
2. push buttons will be replaced by IR sensor network in practical 
3. person count LEDs are not needed in practical


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