This Multi Siren Tones Circuit with the UM3561 chip is like a tiny sound studio for emergency vehicles.
This special chip UM3561 can create all kinds of siren sounds, from wailing police sirens to urgent ambulance tones.
With just a few extra parts and a speaker, you can build this circuit to bring those sounds to life.
Beep boop, wee woo wee woo, rat tat tat the choice is yours!
Circuit Working:
Parts List of police siren circuit:
| Category | Component | Quantity | Notes |
|---|---|---|---|
| Resistors | 220k | 1 | 1/4 watt |
| 220Ω | 1 | 1/4 watt | |
| Capacitors | Electrolytic 100µF 25V | 1 | |
| Semiconductors | IC UM3561 | 1 | |
| Transistor 2N2222 | 1 | ||
| Zener diode 3V | 1 | ||
| Other Components | Speaker | 1 | |
| Battery 9V | 1 |
The UM3561 is a versatile ROM IC known for its ability to generate various siren tones including those resembling police, ambulance, fire brigade and machine gun sounds.
Operating at low power, this 8 pin IC can function down to 2.4V.
This IC, designed primarily for toy applications, features an integrated oscillator and tone selection pins.
Creating a siren generator with the UM3561 requires minimal external components a single resistor and a speaker driver transistor are all that is needed.
Inside the UM3561, the external resistor connected to OSC1 pin 7 and OSC2 pin 8 controls the frequency of the oscillator circuit.
Using a 220k resistor typically produces satisfactory results.
The resulting oscillations are then directed to a control circuit, which operates based on the selected tone via connections to SEL1 pin 6 and SEL2 pin 1.
The control circuit sends the signal to an address counter and then to the ROM, with the tone pulses available at output pin 3.
Since the sound output is relatively weak an amplifier is necessary for louder sound.
A single NPN transistor can be used for this purpose.
Changing the siren tones is simple, simply adjust the pin connections of Sel.1pin 6 and Sel.2 pin 1 as follows:
- Sel1 pin 6 Sel2 pin 1 tone
- NC NC police siren
- +3V NC fire engine sound
- Ground NC ambulance siren
- NC +3V machine gun sound
You can configure the IC UM3561 as shown in the following diagram in order to generate various other siren tones such as fire siren ambulance siren and gun sound effect.
Formulas and Calculations:
We will depend on the features of the UM3561 integrated circuit IC, a specialized sound effects IC with the ability to produce a variety of tones and sound effects, together with the components you provided, to construct a basic multi-tone siren circuit.
The formulas to built a above circuit is mentioned below:
Speaker Current:
To power the speaker, the signal from the UM3561 is amplified by the transistor.
One way to estimate the current flowing through the speaker is to:
ISpeaker = VCE(sat) / RSpeaker
where,
- VCEsat is the transistors collector emitter saturation value, which is usually about 0.2V and
- RSpeaker is the speaker impedance.
Regarding a speaker with an 8Ω impedance:
ISpeaker = 9V−VCEsat / 8Ω = 9V- 0.2V / 8Ω = 1.1A
This current is theoretical in actuality, the maximum ratings of the transistor and the speakers power handling capacity may restrict the real current.
Transistor Base Resistor:
This resistor controls the amount of current that flows from the UM3561 to the 2N2222 transistors base. To guarantee correct transistor operation, the value is chosen.
Regarding a 220Ω resistor:
IBase = VOUT−VBE / RBase
where,
- VOUT is the output voltage of the UM3561, which is around 9V or less if it is modulated.
- The base emitter voltage of 2N2222 is denoted as VBE and is usually around 0.7V.
So:
IBase= 9V−0.7V / 220Ω = 38.6mA
This ought should be enough to push the transistor to saturation, which will enable it to completely activate and power the speaker.
With this circuit configuration, the UM3561 can produce a range of tones, which the 2N2222 transistor amplifies to power a speaker.
A constant voltage reference is provided by the Zener diode, and the power supply is filtered by the capacitor.
If necessary, change the resistor values according to the particular specifications or features of the components being utilized.
How to Build:
To build a Simple Multi Siren Tones Circuit using IC UM3561 you need to follow the below mentioned steps:
Connect the UM3561 IC:
- Place the UM3561 IC on a breadboard.
- Connect pin 2 VCC to the ground and pin 3 to the positive supply through a transistor 2N2222 through a R1 220Ω resistor.
Connect the Oscillator Circuit:
- Connect a 220k resistor between pin 7 OSC1 and pin 8 OSC2 of the UM3561 IC.
- This resistor controls the frequency of the oscillator circuit.
Add the Transistor:
- Connect the NPN transistors collector to the positive terminal of the speaker and its emitter to ground.
- Connect pin 3 of the UM3561 IC to the base of the transistor through a current limiting resistor 220Ω
Connect the Speaker:
- Connect one terminal of the speaker to the collector of the transistor and the other terminal to VCC.
Power Up:
- Power up your circuit using the appropriate voltage 2.4V to 5V and enjoy the siren sound produced by the speaker.
Note:
- Make sure to refer to the UM3561 datasheet for the exact pin configurations and specifications.
- Additionally, be cautious with the polarity of the connections to avoid damaging the components.
Conclusion:
To conclude, the Multi Siren Tones Circuit using IC UM3561 is a simple and cost effective solution for generating various siren tones.
By utilizing the UM3561 ICs built in oscillator and tone selection pins along with a few external components, it is possible to create a versatile siren generator suitable for toy applications or hobby projects.
With its ability to simulate police, ambulance, fire brigade and machine gun sounds this circuit offers a fun and engaging way to add sound effects to different projects.
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