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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

TICKING BOMB


This circuit produces a sound similar to a loud clicking clock. The
frequency of the tick is adjusted by the 220k pot.
The circuit starts by charging the 2u2 and when 0.65v is on the base of
the NPN transistor, it starts to turn on. This turns on the BC 557 and
the voltage on the collector rises. This pushes the small charge on the
2u2 into the base of the BC547 to turn it on more.
This continues when the negative end of the 2u2 is above 0.65v and
now the electro starts to charge in the opposite direction until both
transistors are fully turned on. The BC 547 receives less current into
the base and it starts to turn off. Both transistors turn off very quickly
and the cycle starts again