Connect and share knowledge within a single location that is structured and easy to search. I'd like to know how a 'hand clap' switch works. How is the clapping sound detected? How can it be differentiated from whistling, people talking, a barking dog, Can it be another kind of sound?
The most famous example of this was "The Clapper". See the patents for the details: 1 and 2. What's typical for clapping hands is that it's a sudden short, but strong sound. The sound of a barking dog may look somewhat similar, but the peaks will be longer. A possible way to detect it is to trigger an MMV with the input signal if it's higher than a certain threshold, and see if this high level is still present when the MMV times out.
If it isn't it was probably clapping hands. You'll have to experiment with threshold level and MMV time. The response of a hand clapper is basically the impulse response of your transfer function. We can theoretically calculate the output clock signal status using the following formula. On receiving input signal on the first clap, Q1 gets activated, LED 1 d1 starts glowing.
The switch circuit is controlled by a relay and the output is obtained from pin2. Similarly, on receiving another clap, pin4 gets activated and LED2 d2 if connected glows and LED1 stops glowing, likewise, this process continues. It is a concept which controls turns on or off the light or electronic appliances by clapping action.
It is similar to oscillator like monostable, which has only one stable state. The term transistor was originally derived from the phase transfer resistor, as the resistance of the output electrode was controlled by the input circuit. We used bipolar junction transistor BJT. Bipolar junction transistor consists of a pnp transistor and b npn transistor.
In a pnp transistor, a thin layer of n-type semiconductor is sandwiched between two layers of p-type semiconductor. Relays are one of the oldest, simplest, and yet, easiest and most useful devices. Before the advent of the mass produced transistor, computers were made from either relays or vacuum tubes, or both.
A relay, quite simply, is a small machine consisting of an electromagnet coil , a switch, and a spring. The spring holds the switch in one position, until a current is passed through the coil. The coil generates a magnetic field which moves the switch.
It's that simple. You can use a very small amount of current to activate a relay, and the switch can often handle a lot of current. The relay we are going to look at is the Bosch 5 pin relay. Bosch is a German manufacturing conglomerate who also happen to own Bosch Telekom and Blaupunkt , but they are not the only manufacturer of this relay. The Bosch 5 pin relay is the most widely usedand versatile relay, and it can handle up to 30 amps, which is more than suitable for most applications.
Looking at the diagram to the right, we see the pin out of the relay. Note that each pin is numbered, 85, 86, 87, 87a, and The 30 pin is set perpendicular to the other pins to let you know where each pin is at although, most relays are labeled at the bottom. Normally, it doesn't matter which way you pass the current, because if you hook it up backwards, the coil will still activate the relay.
However, relays sometimes have an odd tendency to turn themselves back on briefly. To counter this, a diode a one way switch is placed between 85 and This is referred to as a tamping diode. A diode wall have a very high resistance in one direction, and a very low resistance in the opposite direction. When a tamping diode is used, it is important that you hook the coil up according to polarity. If a tamping diode is used, and you hook it up backwards, you will essentially be shorting a wire out, which sucks, because you can and will burn something up.
If the coil is not activated, 30 will always be connected to 87a. Think of that pin as"87, always connected". When current is applied to the coil, 30 is connected to Here, polarity does not ever matter. You can connect30 up to positive or negative, and that is what you will get out of 87 or 87a. As you can see, the coil is in no way connected to the switch part of the relay. This can allow you to completely isolate one circuit from another.
You can even use a separate power supply to control the relay. The clap sound sensed by condenser microphone is amplified by transistor T1. IC1, commonly used as a timer, is wired here as a monostable multivibrator. Triggering of IC1 causes pin 3 to go high and it remains high for a certain time period depending on the selected values of R7 and C3.
C3 Seconds where R7 is in ohms and C3 in microfarads. On first clap, output pin 3 of IC1 goes high and remains in this standby position for the preset time. Also, LED1 glows for this period. The output of IC1 provides supply voltage to IC2 at its pins 8 and 4. Now IC2 is ready to receive the triggering signal. On second clap, a negative pulse triggers IC2 and its output pin 3 goes high for a time period depending on R9 and C5. This provides a positive pulse at clock pin 14 of decade counter IC IC3.
Decade counter IC3 is wired. Each pulse applied at clock pin 14 changes the output state at pin 2 Q1 of IC3 because Q2 is connected to reset pin The high output at pin 2 drives transistor T2 and also energises relay RL1. A free-wheeling diode D1 prevents damage of T2 when relay de-energises.
During the practical implementation of the project, some of the values or components had to be changed in order to get more accurate result. The circuit was first performed on bread board and only after successful implementation and satisfied output, it was built on a vero board. In the output, a bulb is used instead of an LED. A red LED is used to indicate the first clap.
This is due to the tolerance of the components used in the circuit. Assemble the circuit on a general-purpose PCB and enclose it in a suitable box. This circuit is very useful in field of electronic circuits. By using some modification it area of application can be extended in various fields. It receives a clock signal through the clock input and in the sequential manner it turns ON all the 10 outputs, every time it gets the clock input pulse.
In order to get familiar with the working of the IC, it is essential for the one to get familiar with the every pin of the IC. These IC consist of 3 input pins along with 10 output pins also have one pin for ground and one more for the power supply and one more pin for the Carry out. Pin diagram of the IC is designed below —. At the time when some one slap in front of the Mic the sound signal is converted into the electrical signal by the condenser microphone.
These signals are then given to the transistor T1 base which in return trigger the IC1 pin2. And with the help of the formula shown below the time period for which the output stay in the high position can be calculated —. At the moment the output from the IC1 pin 3 is given to CD decade counter 14 pin, which supply a clock pulse for the proper working of IC2.
The counting of the CD begins from the zero after getting the clock input. And it moves to forward one by one at each time whenever pin 14 moves to high as in front of the mic we clap. Like we get output from the pin 2 for the first clap i. Q1 and LED1 will shine and the device connected to relay start operating. While for the second clap output will receive at pin 4 and LED2 will shine while at this time LED1 turn off and so on. At each output point you need to attach the individual relay.
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