What is a Tone Generator?
A tone generator is a signal generator
circuit which converts applied electrical signals to audio signals. It
can be used to produce dial tones in telephones or produce sirens in
ambulances or VIP vehicles etc or to generate melody tunes in toys, door
bells etc. It can send electrically generated audio pulses to specific
components. It can also be used to test the audio equipments.
It basically creates an electric signal
and converts it into sound. Different type of tone generators generates
different audio signals depending on the application. The source from
which the electronic signal is applied also varies with the application.
2 Melody Generator Circuits
- Melody Generator Using IC UM66:
IC UM66 is a small transistor type IC
with 3 pins. It is a ROM IC with a prerecorded music inside. When power
is applied, IC oscillates and its output gives the music notes. It is
necessary to amplify the output in order to hear through the speaker.
For this, a single transistor amplifier is sufficient. IC UM66 works
well in 3 volts but the power supply can be up to 4.5 volts. So a Zener
diode based regulated power supply is used. If the supply voltage is 3
volts (2 pen cells), there is no need for the zener and the power supply
can be directly connected to the IC. Here 9 volt battery is used to get
loud sound. When power is applied, IC oscillates and the sound can be
heard through the speaker. You can use a small 2 inch (4 ohms) speaker
or a Mylar speaker (one used in toys). It can be used in toys and door
bells.
This is a simple battery operated Music bell circuit that generates a sweet melody for one minute when it is triggered. It uses the ROM IC UM66 to produce the melody. The music stops automatically.
A push switch is used to trigger the
circuit. When the push switch is pressed momentarily, NPN transistor T1
conducts and pull the base of T2 and it also conducts. When T2 conducts,
C1 charges and provides power to IC UM66. Zener diode ZD is used to
regulate the supply voltage to UM66 to 3 volts. When UM66 gets 3 volts
supply, it oscillates and the music tone from it will be amplified by T3
which can be heard through the speaker. Use a small 2 inch speaker.
- Musical Door Bell using IC 3481
Generator
IC UM 3481. The circuit requires only low voltage from 1.5V to 3V for
its operation so that pen cells can be used for the purpose. The circuit
requires only a few discrete components in addition to the Melody
Generator IC.
About the Melody Generator
IC UM3481 is a Multi-Instrument Melody
Generator IC designed for the purpose of Melody generation in various
gadgets. It is widely used in Door bells, Alarm systems, Reverse horns,
Toys, Clocks, and Timers etc. Its important features are:
- Low voltage operation from 1.5V to 3Volt.
- 8 beat selectable.
- Low standby current.
- 3 timbers like Piano, Organ and Mandolin.
- 512 note memories up to 16 songs.
- 5 tempos available through mask setting .
- 8 playing modes by user setting.
- 14 tones selectable.
- One built in RC oscillator.
- On-Chip envelop modulator and Pre amplifier.
The UM3481 series is a
mask-ROM-programmed multi-instrument melody generator, implemented by
CMOS technology. It is designed to play the melody according to the
previously programmed information and is capable of generating 16 songs
with 3 instrument effects: piano, organ and mandolin. It also includes a
pre-amplifier which provides a simple interface to the driver circuit.
Absolute Maximum Ratings
DC Supply Voltage …………………………………… -0.3V to +5.0VInput Voltage Range ………………………………… Vss-0.3V to Vdd+0.3V
Operating Ambient Temperature ……………….. 0°C to +70°C
Storage Temperature ………………………………… -10°C to +125°C
Types
There are different versions of 3481 series Music Generator.IC UM 3481
It can generate 8 song tunes like Jingle
bells, Santa claus coming to town, Silent night Holy night, Joy to the
world, Rudolph the Red nosed Rein deer, We wish to you a Merry
Christmas, O come All Ye Faithful and Hark The Herald Angels Sing.
It generates 12 tones like American
Patrol, Rabbits, Oh My Darling Clemantine, Butterfly, London Bridge is
Falling Down, Row Row Row your Boat,Are You Sleeping, Happy Birthday,
Joy Symphony, Home Sweet Home, Weigenlied and Melody On Purple Bamboo.
It generates only 5 tunes like The Hawaiian Wedding Song, Try To Remember, Aloha OE, Love Story and Yesterday.
It
is very simple to make a Music generator using ROM IC UM 3481. This IC
has a programmed oscillator inside. Only a 100K resistor and a 33 P
capacitor are sufficient to set the oscillating frequency of the IC’s
internal oscillator. Since the output is feeble, a transistor amplifier
using a general purpose transistor like AC 187, BC548 etc can be used to
amplify the sound.
The IC is a low power one and works between 3-5 volts. If higher power supply is used, a 3 volt Zener regulated power supply should be used. It works well in 2 pen cells. Speaker should be small 1-2 inch 4-8 ohms one. On each press of Push switch, the music tone changes.
The IC is a low power one and works between 3-5 volts. If higher power supply is used, a 3 volt Zener regulated power supply should be used. It works well in 2 pen cells. Speaker should be small 1-2 inch 4-8 ohms one. On each press of Push switch, the music tone changes.
A Siren Generator using IC UM3561
IC 3561 is a tone generator that can
produce 4 sirens like Police Siren, Ambulance Siren, Fire brigade siren
and Gun sound. The sound depends on the connections in its pin 6.
1. Pin 6 – No connection – Police siren2. Pin 6 – Connected to pin 5 – Fire engine siren
3. Pin 6 – connected to ground – Ambulance siren
Like
UM66, IC 3561 also works in 3 volts and the maximum voltage that can be
tolerated is 4.5 volts. So a Zener diode based power supply is used for
the IC. Resistor R2 is 220 K which is responsible for the oscillation
of the IC. Do not change this value. If it is changed, the tone will be
different. Output from the IC is amplified by T1. Speaker can be a small
2 inch 4 ohms speaker or Mylar speaker. You can use a three way switch to select different tones.
I hope you have understand the concept
of the tone generator and its applications if any furthermore queries on
this concept or on the electrical and electronic projects leave the comments below.
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