Indian Institute of Technology Hyderabad Anti sleep Alarm for Students M. Rohit Reddy- cs12b1022 Soumith Raju K – cs12b1037 T Rohit Reddy – ee12b1035

Circuit Diagram:

Uses: This circuit saves both electricity and time for students. It helps to prevent them from dozing off while studying. It is also useful for drivers. It can be used in heavy vehicles which travel during nights.

Components Bread board IC1 (CD4093),IC2(CD4020) Piezo elec buzzer Relay switch 60watt 230v bulb 12v DC adapter and AC power supply Resistors and variable resistors(22kohm), transistors, diodes, capacitors Push on button Connecting wires

How does our circuit works ???  Every 30 min, the buzzer sounds just like snooze.  The buzzer sounds for 1 minute until the push on button is not pressed.  If the push on button is pressed, the buzzer resets for the next 30 minutes.  If the button is not pressed, the bulb goes off.

The circuit is built around schimdt trigger NAND gate IC1, timer IC2, transistors BC547, relay RL1 and buzzer. IC1 is used to generate clock for the timer IC2. The time period can be calculated as T=1.38 x R x C, R= R1 + VR1, C=C2. The timer IC 2 is 14 stage ripple counter.

Around half an hour after the reset, transistors T1,T2 and T3 drives the buzzer to sound and intermediate beep. If IC2 is not reset at that time, around one minute later, the output of gate N4 goes high and transistor T4 conducts. As the output of gate N4 is connected to the clock input (pin10) of IC2 through diode D3, further counting stops and relay energizes to deactivate all the appliances. This state remains same until reset.

Time calculations: R= R1 + VR1 = 15 kilo-ohms C= C2= 10 micro-farad T= 1.38 RC = 0.21 seconds, as IC2 is a 14 stage ripple counter, the time delay is calculated as follows: t1= 2**13 (2 to the power 13) * 0.21= minutes. And time delay to put off the bulb is t2= 2**8 (2 power 8) * 0.21 = 53.8 seconds

**Thank you**