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Datasheets : Sound and Music - Output Device
What does it do?
How do they operate?A variety of modules are available that can be used to add sound or music to electronic systems. The simplest and lowest in cost is the Melody generator IC which plays ‘It’s a small world’. Two Melody ICs are available, each of which gives a choice of three tunes. A 20 second sound recorder module is available that allows up to 20 seconds of sound to be recorded and replayed. Voice modules make a variety of sounds. All of these modules can be operated on their own; or they can be triggered by a transistor used as a switch, so that they become output subsystems.
When the push switch labelled ‘Tune 1, 2 or 3’ is pushed the corresponding tune plays. It keeps repeating if the switch is held down. If the switch labelled ‘Cycle’ is pressed then the IC plays Tune 1, then Tune 2 and then Tune 3. The supply voltage should be in the range 3.0 – 3.5V. If a higher voltage supply is used then a resistor can be included in series between +Vs and pin 7. The current consumed is about 10mA, so a +5V supply would require a series resistor of about 220W. Pins 9 and 10 are connected to a piezo transducer or a small loudspeaker.
20 second sound recorder module The 20 second sound recorder module (Rapid 13-0660) records up to 20 seconds of sound when the white 'Record' button is pressed. The LED lights while recording is taking place. The recorded sound can be replayed by pressing the green 'Play' button. The recorded sound is not lost when the batteries are changed. The supply voltage needs to be in the range of 4.5 - 6.0V.
 To operate them with a separate switch the top and case can be separated (by levering the top out with a small screw driver). Underneath there is a push switch and a pair of terminals.
The ‘voice’ is triggered by pressing the switch, or by soldering leads to the ‘A’ and ‘B’ terminals and attaching them to a remote switch.
Including sound and music in a larger system
In the case of the Melody generator IC and the Melody ICs the transistor switch subsystem is used to switch current to the unit on and off by placing the transistor switch in the circuits for the units in place of the wire link shown in red in the above circuit diagrams. The emitter (‘E’) terminal of the transistor switch should be connected to the 0V line. The sound unit will operate when the signal into the transistor switch is high. In the case of the Melody ICs any of the switches marked ‘Tune 1, 2 and 3’ and ‘Cycle’ can also be replaced with a transistor switch. The 20 second sound recorder module and the voice module can be operated with a transistor switch by connecting the emitter (‘E’) terminal of the transistor switch to the pad marked ‘A’ and the collector (‘C’) terminal of the transistor switch to the pad marked ‘B’. Alternatively the on/off switch can be shorted out, the batteries removed and replaced with a power signal from the main subsystem – just like any other output device. Some music generators cannot be easily adapted in this way. For example, the terminals of the Rapid Music Unit (Order code 13-0620) are made from a metal that cannot be soldered to. Possible applications
Making
TestingFirst check the operation of the sound unit without any connections. Next check the operation using the transistor switch. This can be operated by connecting a piece of wire to make its input signam high or low. Fault FindingIf there is a fault, check the orientation and pin connections of the transistor. Check the voltage of the input signal to the transistor. Alternatives
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Voice modules are designed for use in children’s toys. When the top is pushed down they make a variety of sounds: ‘witch laughter’, ‘lion roar’, ‘owl hoot’, ‘bird song’, ‘snoring’ and one saying ‘I love you’.
If the sound unit is being controlled by a transistor switch, a PCB-mounted terminal block is useful for connecting the wires between the electronic control system and the sound unit.