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Sound Effects

16 Tune Musical Door-Bell

16 Tune Musical Door-Bell

Gives 16 different tunes by pressing switch sixteen times

 

This simple circuit finds application as a doorbell as well as telephone intruder music player, toy or attention call bell.

The heart of the circuit is an IC4822 named as IC1. IC4822 is a programmed ROM, which generates 16 musical tunes when it gets triggered. The main feature of this IC is that it has inbuilt tone generator, rhythm generator, modulator, oscillator, frequency divider and preamplifier. So a very few number of components have to be connected externally to set up timing and to build an external AF amplifier/driver circuit.

 

About the circuit:

When switch S1 is pushed on, voltage at pin 4 triggers IC4822. After triggering, IC plays a musical tone.16 musical tones can be heard simultaneously on pressing S1 sixteen times.

Transistor T1 is used as an amplifier connected to chip preamplifier output at pin 11 to drive 8W loudspeaker.

Resistor R1 controls the tempo i.e. the speed at which tune is played. Tempo can be varied as per choice by changing the value of R1.

This musical bell generates 16 musical tones by pressing switch sixteen times. It can be used as a door-bell, telephone intruder alarm or attention call bell. 
           The circuit diagram is shown in figure. The circuit is build around IC1, which has inbuilt oscillator and preamplifier circuit. The output of IC1 drives 8 speaker through driver transistor.

16 Tune Selective Musical Bell

16 Tune Selective Musical Bell

Play a selected tune from 16 tunes generated by the circuit

 

This musical bell provides a facility to select any of the 16 tones generated by IC 4822 (IC1). IC1 is a programmed ROM, popularly known as musical doorbell IC. This IC has an on-chip oscillator and preamplifier circuit. So a very few number of components have to be connected externally to set up the timing and to build up an external AF amplifier/driver circuit.

 

About the Circuit:

When switch S2 is closed and S1 is in up position, IC1 gets triggered due to the triggering voltage at pin4. IC1 plays a musical tone.16 musical tones can be heard simultaneously by pressing S2 sixteen times.

To play a selected tune, selector switch S1 is pushed down. First tune is selected. Other tunes can be selected by pressing S1 again. The selected tune can be played any number of times by pressing S2.

Capacitors C1 and C2 are used to avoid 50Hz interference from mains. Resistor R2 is used for frequency control at which the tune is played. Transistor T1 is used as a driver transistor connected to pin11 which drives the 8W loudspeaker.

Touch Sensitive Musical Bell

Touch Sensitive Musical Bell

This musical bell generates different musical tones every time the plate is touched. If the plate is touched for more than two seconds, it gives a sound (beep-beep) different from the musical tone. Musical tune is produced after removal of the hand touching the plate. Only a few additional components are required to achieve excellent results.

About the Circuit:

The heart of the circuit is a musical tone generator IC4822 (IC1). This is a programmed ROM IC, which has inbuilt oscillator and tone generator.

Touch plate is connected to base of transistor T1. When the plate is touched, T1 conducts and IC1gets triggered. Hence it generates a musical tone. The output at pin 11 of IC is driven by transistors T2 and T3 and in turn drives 8W Loudspeaker.

Care should be taken that battery supply should not be greater than 3V.

 

This musical bell generates different musical tones every time the plate is touched. Musical tune is generated after removal hand from the touching plate.

                            When the metal plate is touched, IC gets triggered and generates melodious tone. On next touch, next tone is generated. Thus 16 tones can be heard simultaneously by touching plate 16 times. The speed at which the tune is played can be set with the help of preset.

Electronic Harmonium

Electronic Harmonium

Simple circuit generates 15 different notes

                   The modern electronics presents this Electronic Harmonium as a hobby kit or people who are interested to have hands on experience in this field.
                  This harmonium can generate 15 different notes of music (one at a time). It has a PCB with 15 parallel copper strips. Each strip corresponds to one note. So as you put the probe on a strip, the instrument plays a corresponding note.
                  The circuit is build around IC1, which is used as a astable multivibrator. The frequency produced depend on the note selected by the probe. When we put the probe on different strips, we are effectively changing the frequency by changing the resistance between pin7 and pin2 of IC1.

About the Circuit:

                       IC1 as shown in the circuit diagram is wired as an astable multivibrator. When the voltage at trigger input pin2 of IC1 is below 1/3Vcc, output at pin3 changes its state from low to high. This is achieved by putting the probe on strip, which changes the voltage level of pin2 below 1/3Vcc and IC gets triggered. 
                       The IC generates note according to the timing components designed using capacitor C1, resistor R1 and combination of resistors R2 to R16 which are selected using probe. 
                        At a particular instance, the combination of R1 and R2 to R16 charges capacitor C3, and voltage across the capacitor keeps on increasing. When it becomes 6V, the threshold voltage at pin6 makes output at pin3 low. Now C3 starts discharging through R2 to R16. As soon as voltage of C3 goes below 1/3Vcc, pin2 sense this voltage and switches output at pin3 from low to high. In this way, we get the square output at pin3 since C3 charges and discharges through R2 to R16. The charge and discharge times can be varied by changing values of combination of resistors from R2 to R16 through probe which in turn change the charging and discharging periods of C3. Thus the frequency of oscillation is changed and in turn note is changed.
                       For a sweet melody sound it is required to have a symmetrical square wave. Thus R1 should be kept small as compared to R2 to R16. For making the keyboard, PCB with copper parallel strips on it are readily available. Resistors of 5% tolerance only should be used. A resistance with 10% tolerance can change the note considerably.
                       The circuit uses 9V DC supply, so a battery of 9V should be used for satisfactory operation.

Three Tune Musical Bell

Three Tune Musical Bell

Simple low cost melody project

The UM 66T series are CMOS IC is designed for use in doorbell, telephone and toy applications. They are on chip ROM programmed for musical performance produced by CMOS technology, these devices result in very low power consumption, since the UM 66T series include oscillating and mode selection circuit, a compact melody module can be constructed with only a few additional components.

About the circuit:

The circuit uses UM 66T having 64 note ROM memory. Which is capable to store three different tunes.
From fig. The supply is given to IC through a switch S1. When the switch S1 is pressed it will on the IC. The output of IC is in terms of sound. But this signal is not enough to drive the speaker, so transistor T1 is used for amplifying the signal and to drive the speaker. Capacitor C1 is used as a filter capacitor.
The power consumption of circuit is very low. It will work on supply of 3volt.    

Multi-Tone Siren

Multi-Tone Siren

There are different types of siren tones used for different purposes like ambulance, police fire etc. The siren kits available in the market generate normally a single tone. With multitone siren kit, we can generate different types of siren tones for different purposes.  This unique feature of the circuit makes it versatile and useful in wide range of applications like burglar system, lift door open alarm, smoke detector and any other alerting application.

About the circuit:

Versatile UM 3561, 8 pin IC is used here to generate four different audible ones. Basically IC has built in oscillator, control circuit, address counter, ROM and Tone generator etc .The predefined programs generate different tones only with few external components. The IC operates at low voltage of 3 volts upwards. Its quiescent current is as low as 150 micro amperes.
A single resistor between pin7 and pin 8 decides the frequency of oscillations. Pin 1 and 6 are tone selector pins. 
The center - off toggle switch S1 helps in selecting the tone desired in the output. Out put is available on pin 3.The selection table gives the switch poison and tone selected.
The power supply used is from eliminator or battery measuring about 3-9 volts. A zener D1 of 2.7 volts is used to regulate the supply forIC1. R2 is the biasing resistor for zener D1.
The AF section consists of IC2, which is low power audio amplifier IC specially designed to deliver 1 – 8 watts of power at 4 ohms load (Speaker).The output of this amplifier exhibits low distortion and low noise. The input to this amplifier is fed through pin 3 through variable resistance VR1 to adjust the input signal. This acts as volume control. The output of this amplifier (pin 7 ) is fed to the speaker. 

To, Dilip Bhoyar
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