Lab 1 The Clapper
The objective of this experiment was to make students familiarize with the working of
clapper circuit and design a clapper circuit in lab.
The Clapper is a gadget that uses a sound-activated switch sensitive to hand clapping, to
turn off and on any appliance that is plugged into it depending on the number of times you clap.
The clapper can be designed and fabricated using the phase-locked loop (PLL) tone decoder
LM567. This circuit comprises tone generator, speaker driver and speaker section.
The basic parts of a clapper circuit are shown in the following diagram:
Condenser Mic is a censor, which helps in converting audio signals to electrical signals.
Operational amplifier is an amplifier which have high impedence and high output used to perform
mathematical operations by using voltage. This amplifier consisting of two high impedence inputs
one of them is called inverting input labeled as minus (-) and other is called non-inverting input
labeled as plus (+). There is also athird terminal which represents the operational amplifier output.
The 555 Timer IC is an integrated chip used in many timers, oscillator applications and pulse
generation. It can be used as flip flop element to provide time delays.
The D flip-flop traces the input, making transitions with match those of the input D.
The D termed for "data"; this flip-flop stores the value that is on the data line. It can be
thought of as a basic memory cell. A D flip-flop can be made from a set/reset flip-flop
by tying the set to the reset through an inverter.
Bipolar Junction Transistor:
Bipolar Junction Transistor is constructed with three doped Semi-Conductor Regions (Collector,
Base and Emitter) which are separated by P-N junctions and is considered as Semi-conductor
Circuits are open and close electronically and electromechanically by switches and these switches
are called Relays. They control the circuit by closing or opening contacts in another circuit. From
the figure we can see that when contact of relay is normally open then open contact is there and
relay is not energized.
Resistors are device that used in a circuit which allow the limited the total amount of current to
pass. A resistor is two-terminal component that ensures electrical resistance as circuit component.
There are various type of resistors one is called potentiometer which consist of fixed and variable
Capacitor is an electronic device that stores the electrical charge containing conductors which are
separated by insulators. Capacitor is a passive device with Two terminals component that in a
electric field stores a potential energy. And its energy is depending upon the amount of current
The electrical condenser mic is required to detect the applaud sound and procedures it to give an
electrical flag as a yield to control the circuit. The operational intensifier circuit is utilized as a
comparator; any sound flag, which is underneath the limit extend, won't get past. On the off chance
that the sound flag gets over the edge, the enhancer will give a yield, which will trigger the 555
clock IC. The edge i.e. affectability of the mic, can be altered by changing the variable resistor
connected with the mic. In the wake of trigging, the 555 clock IC will give the beats to the flipslump, contingent upon the beats given by the 555 clock IC, the flip-tumble will trigger the hand-
off through the transistor and kept up its state when the two applauds are made and will reset if
another two applauds are made. The flip-tumble will give its yield as per its reality table. The yield
of flip-flounder is associated with the hand-off through a BJT. The BJT is arranged as a switch
here. There are a few reasons why we interface a BJT is associated alongside the Transfer. BJT
has quick DC exchanging, separate the circuit from the heap and the above all it gives substantially
higher current to stimulate the hand-off which flip-flounder can't give. At long last the transfer will
turn on the required gear i.e. driven for our situation will turn ON and remains on until the point
when another two applauds are made. In the event that the flip-flounder is absent, at that point the
drove will be killed instantly after the two applauds are made i.e. it won't remain ON.
R1, R2, R4, R5, R10 = 10,000 ohms
C1, C2, C3, C4 = .1 uF DISC
R6 = 150,000 ohms
C5 = .47 uF Electrolytic
R7, R9 = 100,000 ohms
R8 = 1 mega ohm
ICs and Transistors
R11 = 220 ohms
C1 = 741 OP AMP
R3 = 100,000 ohm trimmer POT
C2 = 555 TIMER
C3 = 4013 Dual D Flip Flop
B1 = 9v Battery
K1 = SPST reed Relay 5v DC coil
Q1 = 2N2222 NPN
MIC = Electronic Microphone
The designed circuit was as follows:
The experiment was conducted in following steps:
1. Required components were gathered and labelled.
2. The values of resistors and capacitors were measure before connecting the components.
3. The circuit was connected according to the schematics.
Discussion and Conclusion
Through this experiment we learned how to build circuits involving a lot of components.
This was more like a project and we built a real device using basic electronic components. The
objective of this experiment was to design a clapper which was effectively fulfilled. We learned
not only about the working of clapper circuit but also the working of basic ICs such as LM 741
and 555 etc. These concepts will help us a lot in future experiments also in applying theoretical
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