9-Way Clap Switch Circuit Diagram With the help of this circuit you can control your home appliances without getting off from your bed. You have to just clap or puff in front of the microphone and the device connected to it become "on" or "off". Features of this clap switch circuit are as follows:-
1. You can simultaneously "on" and "off" one, two or three devices.
2. You are not required to move from your place to "on" or "off" the devices.
3. It will give you visual indication of the appliances also.
The clap switch circuit is build around two IC's -
1. NE555 Timer IC which is configured in monostable mode.
2. 7490 IC which is a decade and binary counter. It contains four master slave flop and also contain divide by two and divide by five counter. It can be used as divide by 9 counter by connecting Q0 with clock input pin1 (CP1) and providing clock pulse to CP0 that is on pin14. It can also be used as divide by 6 counter by connecting Q0 with CP0 and giving input pulse at CP1.
7490 IC will provide you the 9 different combination to "on" and "off" the four different application in 9 claps. Similarly 7492 IC is also available which will provide you 11 different combination of output for controlling the four appliances. And another is 7493 which provide 15 different ways to control the four appliances.
When you clap in front of the Mic, clapping sound is converted into electrical energy by the microphone. These weak signals are then amplified by the transistor which acts as preamplifier. Sensitivity of the signals can be improved with the help of VR1. Now the transistor T1’s output is feed to monostable circuit which is wired NE555 IC. Whenever you clap in front of microphone, output pin 3 of IC1 goes high and this is fed to clock input of IC2 pin 14. The output of IC2 is now provided to transistor T2-T4 through 100 ohm resistor to derive the corresponding relay connected to it. We have also connected different colour LED to indicate the state of the different appliances. If LED glows means that device is "on". If LED does not glows means device is "off".
The output stage of IC7490 (Q0-Q3) for different numbers of clap are shown in tableNo. Claps
of Q0
Q1
Q2
Q3
0
0
0
0
0
1
1
0
0
0
2
0
1
0
0
3
1
1
0
0
4
0
0
1
0
5
1
0
1
0
6
0
1
1
0
7
1
1
1
0
8
0
0
0
1
9
1
0
0
1
Here logic 1 indicates that corresponding transistor conducts to energise the corresponding relay and activate the device connected to it. And logic 0 describes that device is inactive.
The 74LS90 is a simple counter, i.e. it can count from 0 to 9 cyclically in its natural mode. It counts the input pulses and the output is received as a 4-bit binary number through pins QA, QB, QC and QD. The binary output is reset to 0000 at every tenth pulse and count starts from 0 again. A pulse is also generated (probably at pin 9) as it resets its output to 0000. The chip can count up to other maximum numbers and return to zero by changing the modes of 7490. These modes are set by changing the connection of reset pins R1 - R4. For example, if either R1 & R2 are high or R3 & R4 are ground, then it will reset QA, QB, QC and QD to 0. If resets R3 & R4 are high, then the count on QA, QB, QC and QD goes to 1001.
The other high counts can be generated by connecting two or more 7490 ICs. For example, if two 7490 are connected in a manner that input of one becomes the
output of other, the second IC will receive a pulse on every tenth count and will reset at every hundredth count. Thus this system can count from 0 to 99 and give corresponding BCD outputs.
7490 has an inbuilt divide by two and divide by five counters which can be connected in different fashion by changing the connections. It can be used as a divide by 10 counter by connecting QA with (clock) input2, grounding all the reset pins, and giving pulse at (clock) input1. This enables the cascade connection of the inbuilt counters. It can also be used as a divide by 6 counter by connecting Q A with input2, grounding R3 & R4, and giving pulse at input1.
By connecting QA with input1, 7490 can be used for BCD counting whereas by connecting QD with input2, it can be used for bi-quinary counting. Bi-quinary is a system for storing decimal digits in a four-bit binary number. The bi-quinary code was used in the abacus. Pin Diagram:
Pin Description: Pin No 1 2 3 4 5 6 7 8
Function Clock input 2 Reset1 Reset2 Not connected Supply voltage; 5V (4.75V – 5.25V) Reset3 Reset4 Output 3, BCD Output bit 2
Name Input2 R1 R2 NC Vcc R3 R4 QC
9 10 11
Output 2, BCD Output bit 1 Ground (0V) Output 4, BCD Output bit 3
QB Ground QD
12 13 14
Output 1, BCD Output bit 0 Not connected Clock input 1
QA NC Input1
