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It is time-consuming and risky to provide piezo components with strands and to contact them on printed circuit boards yourself. PI Ceramic takes on this step for customers and supplies piezoceramic components with flexible printed circuit boards. Piezo Drivers, Amplifiers & Controllers. Mar 12, 2019  Hi, I am currently designing a driver circuit for Piezo transducer to measure liquid level of a closed sealed steel container. I have used 1 MHz Piezo transducer with a resistance of 5 ohms at resonant frequency, 30 mm diameter and a capacitance of 2200pF.

For a university project, I'm creating my own small speaker. This speaker includes a speaker driver circuit consisting of a transistor and 3 resistors (see figure below).

^{simulate this circuit – Schematic created using CircuitLab} The power source is limited to 1.5V, but I would like to boost this voltage using a voltage boost circuit.

The voltage boost circuit actually is an oscillating circuit including an inductor, diode, switch (oscillating) and a capacitor (see figure below). I think the 'timed switch' can be attached to the 'feedback' pin from the piezo.

Piezo Disc Driver Circuit

Since the piezo driver circuit is a kind of oscillating circuit, I thought it would be nice to combine both circuits. So the piezo driver circuit would be used as the oscillating circuit of the voltage boost circuit.

Both circuits work separately, but not combined. When replacing the light bulb with the piezo, the piezo doesn't vibrate since the capacitor keeps the voltage constant, but the piezo needs to be turned on and off very quickly in order to vibrate.

Somehow, the capacitor needs to power the piezo driver circuit again, but I cannot yet figure out how. Below is my attempt.

Can any of you maybe guide me in the right direction?

I hope you understand what I'm trying to do. Otherwise I'll be happy to try to explain it in a different way.

SamGibson

Piezo Driver Circuit

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I am interested in the use of a microcomputer in a drive circuit for an external drive piezo buzzer.I was reading the FAQ page on the website of a piezo buzzer manufacturer

Under the heading 'Please give me an example of the drive circuit for a Piezoelectric Sounder or a Piezoelectric Diaphragm (External Drive Type).' they said 'Examples of typical drive circuits are broadly divided into case 1 where a transistor circuit is used and case 2 where the product is driven directly from a microcomputer.' and gave the following image as an example.

I am a novice with electrical engineering and I am trying to understand exactly what components are needed in this external drive piezo buzzer drive circuit. The supplementary comments for this circuit diagram suggested people 'consider connecting a Zener diode in parallel with the piezoelectric sound component and Rp if necessary.' Based on this, my understanding is that the necessary components of this drive circuit are - the microcomputer,the diode,the resistor (Rp),the buzzer, anda power source.

Is this correct? Is it possible to build a drive circuit for a piezo buzzer with only these components, or do I something else?

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1 Answer

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You said you were a novice, so here is something simple:

The page you linked to turned out not to be a datasheet, so we don't know anything more about the piezo speaker than what you say. The above circuit should work well enough for most piezo speakers, although it can possibly be driven from a higher voltage, which would yield higher volume.

R1 limits the current thru the base of Q1 when the digital output is high. Figure the B-E junction drops 700 mV, so that leaves 4.3 V accross R1, which causes 4.3 mA base current and will draw that much from the digital output. Most digital outputs can source that much without issue. Check your datasheet. If not, make R1 higher. You most likely don't need as much base drive as this.

When the digital output is high, Q1 will have 4.3 mA of base current, which should easily give it enough current sink capability to pull the collector as low as it can go. Figure you can count on a gain of 50, so that means 215 mA of collector current, which should be way more than required.

D1 is there to give the kickback current of SP1 a place to go when Q1 turns off suddenly. Piezo elements have a significant inductive component as viewed from the driving circuit. If you don't give the kickback current a place to go, then the voltage can get high enough to fry Q1. R2 cause some back voltage to this current to make it die down more quickly, helping the high frequecy response. R2 can probably be a lot lower, but again, you didn't supply a datasheet so all the component values are just rough ideas or guesses at best.

Olin LathropOlin Lathrop$endgroup$

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