Featured Post

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

on
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
2

Night security light

on


Description.
 Here is a simple circuit switches on a light around 2 hours after midnight, the time at which most of the robberies taking place.
This simple circuit is build around a CMOS IC 4060 to obtain the required timing. During day time the LDR has low resistance and keeps the pin 12 of the IC1 high, preventing the IC1 from oscillating. When it is dark the LDR resistance becomes high and the pin 12 of IC1 becomes low and the IC starts oscillating, which indicated by the flashing of LED D3.The values of the timing components R1, R2, C4 are so selected that the out put pin3 of IC1 goes high after 8 hours. That means the high output drives the triac to switch on the lamp around 2’O clock. At morning, the LDR resistance drops and the pin 12 of IC1 goes high and stops the oscillation, making the lamp OFF. The switch S1 can be used to manually ON the lamp. The capacitor C2 prevents false triggering.
Circuit diagram with Parts list.






Notes.
  •  Assemble the circuit on a good quality PCB or common board.
  • The LDR can be general purpose LDR.
  • The light sensitivity can be adjusted using the preset R6.
  • The IC1 must be mounted on an IC holder.

Comments

Post a Comment