This circuit saves both time and electricity for students.
It helps to prevent them from dozing off while studying,
by sounding a beep at a fixed time interval, say, 30 minutes.
If the student is awake during the beep, he can reset the circuit to beep in the
next 30 minutes. If the timer is not reset during this time, it means the student
is in deep sleep or not in the room, and the circuit switches off the light and fan
in the room, thus preventing the wastage of electricity
Circuitry
Things Needed for Making this Antisleep Alarm for Students
timer IC CD4020 (IC2), transistors BC547, relay RL1 and buzzer.
The Schmitt-trigger NAND gate (IC1) is configured as an astable multivibrator
to generate clock for the timer (IC2). The time period can be calculated
as T=1.38×R×C. If R=R1+VR1=15 kilo-ohms and C=C2=10 μF, you’ll get
‘T’ as 0.21 second. Timer IC CD4020 (IC2) is a 14-stage ripple counter.
Around half an hour after the reset of IC1, transistors T1, T2 and T3 drive
the buzzer to sound an intermediate beep. If IC2 is not reset through S1
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 (pin 10) of IC2 through diode D3, further counting stops and relay
RL1 energises to deactivate all the appliances. This state changes only when
IC1 is reset by pressing switch S1.
Assemble the circuit on a generalpurpose PCB and enclose it in a suitable
cabinet. Mount switch S1 and the buzzer on the front panel and the relay
at the back side of the box. Place the 12V battery in the cabinet for powering
the circuit. In place of the battery, you can also use a 12V DC adaptor.
It helps to prevent them from dozing off while studying,
by sounding a beep at a fixed time interval, say, 30 minutes.
If the student is awake during the beep, he can reset the circuit to beep in the
next 30 minutes. If the timer is not reset during this time, it means the student
is in deep sleep or not in the room, and the circuit switches off the light and fan
in the room, thus preventing the wastage of electricity
Circuitry
Things Needed for Making this Antisleep Alarm for Students
- Relay
- Bulb
- Transistor or SCR
- Push to ON /OFF switches
- Resistance & capacitor
- Pizzo buzzer
- Doide
- IC: IC CD4020
timer IC CD4020 (IC2), transistors BC547, relay RL1 and buzzer.
The Schmitt-trigger NAND gate (IC1) is configured as an astable multivibrator
to generate clock for the timer (IC2). The time period can be calculated
as T=1.38×R×C. If R=R1+VR1=15 kilo-ohms and C=C2=10 μF, you’ll get
‘T’ as 0.21 second. Timer IC CD4020 (IC2) is a 14-stage ripple counter.
Around half an hour after the reset of IC1, transistors T1, T2 and T3 drive
the buzzer to sound an intermediate beep. If IC2 is not reset through S1
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 (pin 10) of IC2 through diode D3, further counting stops and relay
RL1 energises to deactivate all the appliances. This state changes only when
IC1 is reset by pressing switch S1.
Assemble the circuit on a generalpurpose PCB and enclose it in a suitable
cabinet. Mount switch S1 and the buzzer on the front panel and the relay
at the back side of the box. Place the 12V battery in the cabinet for powering
the circuit. In place of the battery, you can also use a 12V DC adaptor.
you have sort out the problem of electricity but may i ask what will we do to switch the lights ON again? coz the switch is already in ON state!!:o
ReplyDeleteReset it by giving standard input to pin no. 11
ReplyDeletepin diagram
ReplyDeletecan i reduce the timer from 30 minutes to 10 minutes? what kind of component that i need to change.
ReplyDeleteanyone?
ReplyDeleteIncrease resistance lets say aproxx 40k of R1
ReplyDeleteor decrease the c capacitor to 2Micro F only C2 and C3
sorry for late reply
ReplyDeletedo u have the simulation for this circuit?
ReplyDeleteright now i don't have ...but i will try to create it .. okkay
ReplyDeletei'm using proteus 7 professional to do the simulation. but, it does not work. even my hardware connection also fail. suddenly, the source become hot. if your simulation run perfectly, do u mind share it with me? (send it to my email, mananto_566@yahoo.com). i really appreciate if u could do that. i'm currently doing this circuit for my final year project.
ReplyDeletei am using Tina Simulator ... it work fine in it .. and also in TopSpice
ReplyDeletetry c 25Mico f and R 100kohm.
ReplyDeletetry in Tina or topspice
can anyone please describe it step to step
ReplyDelete1)the parallel capacitor role in astable
2)how each connection of IC2 is working
3)why capacitor is used across push button
4)D4 diode function?
please help me
please step to step description is required in simple wordings!
ReplyDeleteIf any one wants to make a little extra money..contact me but I need it on urgent basis