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# mini project low voltage protection system using annunciator

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#### archanapurvi

##### Newbie level 1
Hi in our college for our first year mini project , we were given a problem statement and based on it we have to find a solution , but i am not able to so here is the problem statement
"low voltage protection system using annunciator
generate 5volt power supply from 230volt ac and activate beeper when
power supply is below 180volt.choose components with appropriate
materials.list the important property based on which the material is
chosen for the components .draw the waveforms of current and voltage
at specific branches and node.find the laplace transformations ."
:-(;-)

Build yourself the 5 volts power supply, do a search on google for a circuit. You will need something like a 6V mains transformer - be very careful of the 230V connections to it. tape a piece of plastic over the terminals, else touching them might kill you. In the power supply there will be some diodes, converting the AC to DC, from the positive output of the diode connect a resistor join this to a resistor going to earth. Make one of these resistors about 10K ohms. Now ios the cunning bit, with 230V AC in (careful with your measurements!!), select the other resistor to give about 2.3V DC. Note what the actual voltage is. Now you know what the equivalent voltage would be for 180V in (1.8V!!).
Now google for a COMPARATOR circuit, use the above point as one input and a pot across the 5v line for the other. If you have it correct, when the input 230V is 230 V the comparator should give you a +5V output and when it falls to 180VAC the output falls to 0V.
Get hold of your annunciator and if it does not draw too much current connect it between the 5V line and the comparators output. Else put in a current amplifier (one extra transistor)
Frank

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