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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

Simple Electronic Thermostat using IC LM56

Here a schematic of a really simple electronic thermostat using IC LM56. LM56 is a terribly correct twin output low power thermostat from National Semiconductors.LM56 has varied helpful options like internal temperature sensor, 2 internal voltage comparators, internal voltage reference etc. 2 stable temperature trip points (VT1 and VT2) are created by dividing the LM56′s 1.250V internal voltage reference using 3 external resistors (R1, R2 and R3).
There are 2 digital outputs for LM56 .Output1 becomes LOW when the temperature will increase higher than T1 and goes HIGH when the temperature decreases below (T1±Hysteresis Temperature). within the same method, Output2 becomes low when the temperature goes on top of T2 and goes HIGH when the temperature goes below (T2±Hysteresis Temperature).
By connecting a cooler because the load for relay L1 and a heater as the load for relay L2, a really easy and helpful temperature control system will be created.

  • The circuit can be assembled on a Vero board.
  • Use 5V DC for powering the circuit.
  • L1 and L2 can be 5V relays.Their current ratings must be selected according to the load they switch.
  • Do not give more than 10V to LM56.

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