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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

12 Volt Automatic Lamp Fader

12 Volt Automatic Lamp Fader

This circuit is agnate to the "Fading Red Eyes" ambit (in the LED section) acclimated to achromatize a brace of red LEDs. In this version, the lamps are achromatic by capricious the assignment aeon so that college ability beaming lamps can be acclimated after abundant ability loss. The switching waveform is generated by comparing two beeline ramps of altered frequencies. The college abundance access waveform (about 75 Hz.) is produced from one area of the LM324 cloister op-amp active as a Schmitt activate oscillator. The lower abundance access controls the crumbling amount and is generated from the high two op-amps agnate to the "fading eyes" circuit.

The two access waveforms at pins 9 and 1 are compared by the 4th op-amp which generates a capricious assignment aeon ellipsoidal waveform to drive the achievement transistor. A additional transistor is acclimated to alter the waveform so that one accumulation of lamps will achromatize as the added accumulation brightens. The 2N3053 will handle up to 500 milliamps so you could affix 12 strings of 4 LEDs anniversary (48 LEDs) with a 220 ohm resistor in alternation with anniversary accumulation of 4 LEDs. This would absolute about 250 milliamps. Or you can use three 4 volt, 200 mA Xmas timberline bulbs in series. For college ability 12 volt auto lamps, the transistor will charge to be replaced with a MOSFET that can handle several amps of current. See the cartoon beneath the schematic for accessible hookups.

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