# How to simulate Magnetic Transducer Buzzer (SMT8585-03H03LF) in LTspice- any model available?

I am adding a Magnetic buzzer into the design. Buzzer part number is SMT8585-03H03LF from Bestar electronics.

Below are the specifications for quick glance.

Is it possible to get a LTspice model for this kind of buzzer. I see an Magnetic buzzer's equivalent circuit will be Inductor in series with resister. I can get resister value from specifications but no data on coil data.

Added the driving circuit planned. Open drain driver will drive the BJT. Open driver is emulated by DMN2005 in this simulation

UPDATE

I have done the design and testing this. I have few questions on the driver. Below is the simulated file.

Here, I have 2 constraints Based max driving current I am limiting to ~80mA,

1. With Max Ic = 80mA--> total Collector resistance ~ 40Ohms, leaving coil resistance if i add 25 Ohms as collector resister - Because of the drop across this resister (25*0.080 =2V) voltage across buzzer is less ~1.2V.
2. If i reduce the collector resistance to lets say 5 Ohms, Max collector current is =3.2/(5+16) = 155mA which is exceeding the Maximum current specification of the Buzzer

I am preferring to go with Option2 where i am exceeding Max current 155mA with 50% duty-cycle (spec is 100mA).

• Hyper-link to buzzer? May 13 '20 at 14:08
• Primarily model it as a 16 ohm resistor. For a bit more accuracy, add a series inductor (either measured, or guess something like 10 or 50 uH). May 13 '20 at 14:18
• @Andy aka: it is Magnetic tranducer, i have given Part number, Manufacturer and specifications. May 13 '20 at 14:33
• @Andyaka: Now i understood, you are asking Hyper-link for the datasheet. I have added now. Sometimes by logical brain won't work instantly. May 13 '20 at 17:28

Just for fun I measured one of the ubiquitous 10mm cylindrical transducers and it was roughly 43 ohms in series with 4.7mH @ 1kHz. This particular one has a resonance at about 2kHz so it may behave a bit differently at resonance.

simulate this circuit – Schematic created using CircuitLab

With a quick bench test, the behavior at resonance (and even at 1kHz) is indeed different.

To really accurately model the transducer behavior you'd need to model the mechanical motion of the parts.

• Thanks, This answer has given me another doubt. From resonant frequency 2731 Hz (from datasheet), Is it possible to get equivalent inductance value? Whether this resonant frequency can be modelled as LC circuit, May 13 '20 at 17:30
• No, you can't get the inductance from the datasheet. You can model it as an L+R circuit but it won't be all that accurate. It's probably more than good enough if you only care about the driver. Depends what you think you need the model for. I've used a lot of these in designs and never saw any need to model it. You know there's substantial inductance so you should have a flyback diode or other path for the stored energy. Relays are similar, the L+R model does not describe what happens when the magnetic circuit opens and the inductance changes drastically (with stored energy). May 13 '20 at 17:43
• @user19579 The picture from the datasheet that you posted has a note at the bottom. May 13 '20 at 17:57
• @a concerned citizen:which note you are referring to, is that 2731Hz,1/2Dutycycle? May 14 '20 at 4:11
• @SpehroPefhany : I have added new update to my question regarding driver circuit, can you please check that, Jan 6 at 5:50