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Datasheets : Buzzer (and Piezo sounder) - Output Device
What does it do?
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Click on the circuit diagram to download a Livewire file of the circuit that you can investigate and add to your own circuit. |
Buzzers come in a variety of voltages and currents. The power supply for the buzzer (which can be separate from the supply for the rest of the electronics) must provide the voltage needed by the buzzer. Piezo sounders are a type of buzzer. They should not be confused with Piezo transducers – which require an a.c. input voltage to drive them. Some process units provide enough current to drive buzzers. Typical buzzers require currents in the range 10 – 35mA. If CMOS ICs or a higher current buzzer are used then a driver (transistor, Darlington or MOFET) is needed to boost the current. The circuit on the left shows the circuit needed with a driver. |
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Click on the circuit diagram to download a Livewire file of the circuit that you can investigate and add to your own circuit. |
PICs, 555 Timer ICs and the LM324 op-amp can provide higher currents and can drive some buzzers directly. Check the data for the buzzer and the process unit to make sure that the process unit can provide more current than is needed by the buzzer. If this is possible, the buzzer is connected to the 0V rail (as on the left) rather than to +Vs. |
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Buzzers can either be PCB-mounted or connected to the circuit with flying leads. Usually it is neater to mount them on the PCB. |
Buzzers have a positive and a negative terminal, marked on their case. The positive terminal should be connected to the positive voltage supply. The negative terminal should be connected to the signal from the driver.
The graphic on the left shows how part of the PCB might look for a PCB-mounted buzzer connected to a driver.
How part of the PCB might look
If a buzzer with flying leads is used then a terminal block is mounted on the PCB and wires from this are connected to the buzzer.
Build and test the unit that will provide the driving input signal before adding the buzzer.
Make sure that the buzzer switches on and off as power is applied from the driver unit.
If there is a fault, check that the buzzer has been connected the right way round. Check the buzzer by applying power to it directly.
