19-12-2012, 02:11 PM
Beeper Circuit
Beeper Circuit.doc (Size: 32 KB / Downloads: 24)
This circuit produces the sound of a beeper when the water level reaches upto the required limit. Basically the circuit consists of a 555 timer oscillator which is turned ON and OFF periodically.
The second IC is turned ON and OFF by the first IC.
The first IC determines how fast the second IC is turned ON/OFF and second IC determines the tone of the final output
Aim of the circuit:- to make a water level indicator.
Hints for making circuit:- Pin no. 6 and pin no. 2 works together as twins. The second IC works only if it has resistance greater then 50k between the trigger and discharge and the first IC works only if it has resistance greater than 2.2k between the trigger and discharge. The output of 1st IC is given to the reset of second IC. Control voltage of both IC should be connected with the smallest value of capacitor and goes to ground. The final output of the circuit is taken across the 1uf capacitor and its another terminal is connected to the output device. Threshold of 1st is connected with another electrolytic capacitor to the ground and threshold of 2nd is connected with another ceramic capacitor to the ground. Discharge and reset of 1st IC are connected with a resistance and that resistance is also connected to supply input. For 1st IC pin 8 and pin 4 are shorted. Pin no. 3 of 1st IC and pin no. 4 of second are also twins.