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I am looking for a circuit diagram for a high power ultrasonic amplifier.Needs to drive an underwater transducer rated at 50 watts.Currently using a single HexFet driving a 1:25 toroid to 1000vpp, but I need to increase the duty cycle past 1% for more output power. Rail Output Operational Amplifiers AD8541 General-Purpose CMOS Rail-to-Rail Amplifier ADP7104 20 V, 500 mA, Low Noise, CMOS LDO. Ultrasonic Distance Sensor (Simplified Schematic: All Connections and Decoupling Not Shown). Circuit Operation The ultrasonic ceramic transmitter is a 400ST160 made by Pro.

1. Ultrasonic Transducer Driver Amplifier Circuit Breaker
2. High Power Ultrasonic Transducer
3. Ultrasonic Transducer Driver Amplifier Circuit Schematic
4. 40khz Ultrasonic Circuit Schematic
5. Ultrasonic Amplifier Circuit

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My project needs to drive a medium power ultrasonic piezoelectric transducer from a sine wave (/ sawtooth) sweep generator that sweeps +/- 2% of the transducer resonant frequency.

The question: What are my simplest options for driving these transducers from a DDS generated shaped signal, with reasonably low distortion (5-10%)?

1. Use a power amplifier IC off a higher voltage rail, with lots of heat sinking, to directly drive the transducer
2. Use a power amplifier IC, then (?) a transistor current amplification stage, then an appropriate (need help identifying) step-up transformer to drive the transducer
3. Use some sort of (need help identifying) class D high power amplifier IC that would not need much heat sinking (Edit:Not a solution, see Note 7).
4. Some other option entirely
5. Edit: From suggestion below Identify an off the shelf OEM amplifier module that meets the parameters and constraints.

UPDATE: [15-Oct-2012] Option 5 above seems best answer, if a suitable OEM module or two could be pointed out - None found in my research so far. Hence leaving question open.

The sweep waveform generation is through a DDS IC, AD9850, Datasheet here: AD9850 CMOS 125 MHz Complete DDS Synthesizer

Driver wifi asus x451ca windows 7 32bit. One of the transducers available to me: 5938D-25LBPZT-4 (Ultrasonic Langevin Transducers)

• Resonant frequency: 25 KHz
• Resonant impedance: 10-20 Ohms
• Capacitance: 5400 pf +/-10%
• Input power: 60W
• Datasheet: I wish I could find one!

The transducer would change case to case, from 20KHz to 135KHz, each in the 50-250 watt range, similar in design to the one above.

The driver designs I have seen for these transducers typically use switching i.e. square waves to drive them, MOSFET driven, with Vpp 100v in some cases! (Do these devices even need that kind of voltage?Edit: Evidently so)

Some drivers use tuned filters to shape the waveform to a sine or approximation thereof.

This does not work for my purposes, unfortunately - The project is a single device that would first detect the resonant frequencies of an attached transducer across the full range 20-135KHz, then sweep around each resonant frequency with first a sine wave, (Edit: Removing this requirement as unfeasible: then a sawtooth signal,) at a specified power output, usually around half the rated power of the transducer.

So what I am looking for is the wisdom of this community in suggesting a suitable prototype-friendly approach to getting those DDS waveforms over to the transducer. Thank you all!

Added some notes based on comments and responses received:

1. Waveform accuracy is not super-critical, 5% distortion is very acceptable. Thermal issues and power wastage through dissipation in the amplifier stage are bigger concerns. Cost is a key concern, at least until past the prototype stage.
2. It has been suggested that prebuilt OEM amplifier modules that suit the requirements might be my best bet. While that does appeal, I am still hoping for alternatives in addition to, and examination of, the options I have proposed in my question, hence not marking the answer accepted, yet.
3. Not found any OEM module online yet which covers a 20KHz to 135KHz frequency range, even for 50 watt output. The one suggested in a response is designed for 3.5KHz, and its switching frequency is 100KHz. (Dropped this requirement:Also, wouldn't I require bandwidth much higher than that, to handle a sawtooth wave with even cursory accuracy? I might have to skip the sawtooth requirement, and constrain my question to sine waves, if the sawtooth or other arbitrary waveform delivery is seen by respondents as unattainable at reasonable cost.)
4. New Suggested approach is a Class B with feedback. Caveat mentioned is high dissipation at this amplifier stage. So two adjuncts to my question:
5. Is there a monolithic Class B amplifier IC that might cover the desired frequency range (20KHz to 135KHz, giving up on the sawtooth wave) and power requirements (50 watts max)?
6. What is the range of heat dissipation expected at such a class B stage, as a percentage of expected power delivery to transducer?
7. New About Class D amplifiers, monolithic or OEM: They would need to use switching frequencies of the order of 800KHz or higher, to support a 100-135KHz sine wave with reasonable THD. For a 5% distortion requirement, the switching frequency must be even higher. Such high switching frequency Class D power amplifiers do not seem to exist.

Anindo GhoshAnindo Ghosh$endgroup$

5 Answers

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Try these linear amplifiers made by Apex. They are designed specifically for ultrasound aplications.

Nick Alexeev♦$endgroup$$begingroup$

In many ultrasonics applications you really will need to work with potential differences in excess of 100V to deliver sufficient acoustic power to the medium. This is due to the fairly low impedance the transducers present electrically. Predicting how much voltage you need to achieve a set acoustic pressure however is next to impossible as the transfer functions are non-trivial.

Many ultrasound applications are not terribly concerned with the excitation waveform. This is the reason why many power amplifier stages are very simple push-pull configurations giving a square wave output. Their advantage is two-fold:

1. they can be driven easily from low-voltage signal generation circuits, and
2. they dissipate very little power in the switching elements which is a common design constraint. (Due to the fact that ultrasound transducers are fairly narrow-band, the energy dissipation is shifted to the cable and transducer. Often cooling the transducer is much easier.)

In situations where signal waveform is important, the power amplifier stages I encountered in the past were generally class B push-pull configurations with negative feedback to avoid crossover distortion fed from high-voltage rails. It sounds to me that this would be the way to go in your situation. Note: there will be non-negligible power dissipated in your switching elements.

ARFARF$endgroup$$begingroup$

I think the Piezo Systems EPA-104-115 fits all your criteria except for the low-cost criteria. It costs $2,639.

The AA Lab Systems A-301HS may also fit and is probably as cheap as you'll find. I saw one on ebay for $975.

Searching for piezo driver or piezo linear amplifier didn't turn up anything more affordable in my search, but feel free to double check yourself.

You might also want to read this paper written by a lab that built a less expensive driver for their piezo actuators. Unfortunately their driver is in the 1kHz range but they end by suggesting some methods that might get the kHz up. On the other hand, they say they aren't sure where to get parts that could handle higher frequencies, but it may be a helpful read to understand what makes higher frequencies difficult and could lead toward a solution with some perseverance.

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First of all, yes, you will need voltages on the order of 100V peak (70.7V RMS) to drive 250W into 20Ω.

You can purchase OEM power amplifier modules that cover the power and frequency range you're interested in; this is probably your best bet in terms of getting the prototype operating quickly with low design risk. It may even be the way to go for production, as well. Be sure to select a unit that can deal with the capacitive load.

Here is one example. Interestingly, I find that audio power amplifier modules these days are almost exclusively class-D, with the bandwith limited to 10s of kHz. When I last looked at these some years ago, they were class-AB and had bandwidths of 100s of kHz. Be sure to include 'piezo' or 'ultrasonic' in your search terms.

Dave Tweed♦Dave Tweed$endgroup$$begingroup$

I would observe that a standard piezo or piezo composite transducer has a bandwidth of maybe 20% or so (Possibly an octave with a fairly hardcore matching network for tuning), there is a reason everyone does square wave drive, and it is that the transducers just do not have enough bandwidth to reproduce anything other then a sine wave, it literally does not matter what the drive waveform is the transducer will bandpass it into a sine wave..

Ultrasonic Transducer Driver Amplifier Circuit Breaker

Further even within that bandwidth the group delay varies widely,to the point that even putting a reasonably square multi cycle pulse into the water is difficult enough that Paul Doust used to use it as a party trick demo (As in a squareish burst of sine waves).

I would suggest that whatever you do, a modest (few ohms or so) power resistor in series with the amplifier output would be a good idea to help phase margin.

There are audio amps what will do what you want, but cheap? Not so much, and as I say a H bridge is all you really need because of the transducer limitations (The exception is multiple tones within the available bandwidth where intermod can be an issue).

Class D with GaN might be an option but nobody really has product yet.

High Power Ultrasonic Transducer

Regards, Dan.

Dan MillsDan Mills$endgroup$

protected by Dave Tweed♦Jun 25 '16 at 11:07

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Ultrasonic Transducer Driver Amplifier Circuit Schematic

Ultrasonic Transmitter and Receiver

Ultrasonic sound is a cyclic sound pressure with a high frequency than the upper limit of human hearing equal to 20KHz. Some animals like dolphins, mice, dogs, and bats have a high- frequency limit that is larger than that of the human ear & thus can hear ultrasound. This sound is very low in humans even at high intensities. Ultrasonic waves are found in wide industrial applications such as nondestructive testing of object is illuminated with ultrasonic waves and a repeat of the transmitted waves specifies a flaw, ball bearings, surgical instruments, Fine machine parts & several other objects can be cleaned ultrasonically. When the surfaces of metals can be placed in contact with each other, then the metals can be welded and illuminating the contact with ultrasound. The molecules are moved into relocated in the form of crystalline, making a long-lasting bond. Ultrasonic whistles cannot be received by human beings, but loud to dogs and are used to call them.

Ultrasonic Proximity Sensor

This sensor uses a piezoelectric transducer, which is used to send & notice sound waves. This transducer produces high- frequency sound waves and estimates the echo by the detector which is received back after replicating off the target. Here, time interval can be calculated by sensors b/n sending and receiving the echo to control the distance to the object. When the object enters the operating range the o/p switches. These switches are built with compensation circuit and temperature sensors. In order to change the operating distance caused by temperature variations. This sensor can work in reflex, through beam mode or diffuse., Ultrasonic Transmitter and Receiver

Ultrasonic Transmitter and Receiver

The Ultrasonic Transmitter and Receiver circuit comprises of transmitter and receiver, that operates at the same frequency. When something moves in the area covered the fine balance of the circuit is troubled and the alarm is activated. This circuit is very simple and adjusted to reset it automatically or to stay connected till it is rearrange manually by an alarm. The ultrasonic transmitter is designed with 2-NAND gates wired as inverters and they make a multivibrator the o/p of that drives the transducer.

The P2 trimmer changes the o/p of the TX and for high efficiency it must be made the same as the transducer’s resonance frequency in use. The receiver section built with a transducer to receive the indications which are reflected back to it the o/p of which is amplified by the op-amp 741 IC and transistor TR3. The o/p of the op-amp is taken to the non-inverting i/p of IC2.the amplification factor of which is adjusted by means of P1.

Ultrasonic Transmitter Circuit

The Ultrasonic transmitter and receiver circuit is built with 555 timer IC or CMOS (complementary metal-oxide-semiconductor devices). This circuit works with 9 volts to 12 volts DC.These are preset controlled variable oscillators are specific controlled variable oscillators. The working frequencies specific value is likely to drift due to changes in temperature. The drift in frequency affects the transmission range from the ultrasonic transducer.

Bosch fla 206 software store. Ultrasonic Transmitter Circuit

The circuit of an ultrasonic transmitter and receiver uses an IC CD4017 decade counter. The transmitter circuit is designed with D- flip flop IC and two-decade counter ICs and a few major components. The circuit design generates stable 40kHz signals, which are transferred by the transducer. The RF oscillator built with transistor T1 to produce an 8MHz signal, that works as an i/p to the first decade counter that is built around IC1. The oscillator frequency can be divided to 800 kHz by the decade counter.

The o/p of the first decade counter is fed to the second decade counter, then the frequency can be divided to 80 kHz. The flip flop divides the frequency to half of the frequency of decade counter, then it is transferred by the ultrasonic transducer. The L coil is made with enameled copper wire 36SWG that is looped 15 times around an 8 millimeter diameter of plastic former, which has a ferrite rod and this is used for radio oscillators.

40khz Ultrasonic Circuit Schematic

Ultrasonic Receiver Circuit

The receiver circuit of ultrasonic is powered by a 9V battery. The ultrasonic receiver circuit is designed with a decade counter IC4 and a few components. The working of the transmitter can be checked by converting the 40kHz signal to 4kHz to bring it in the range of audible sound. By using this receiver circuit, the 40kHz transmitter circuit can be quickly tested. Under test, the transducer in the receiver is arranged near to the ultrasonic transmitter.

It notices the transmitted signal (40kHz), that is amplified by the amplifier which is arranged around the BC549 (T2) transistor. This signal is fed to the IC4 decade counter and divides the frequency to 4kHz. T3 transistor strengthens the 4kHz s/L to drive the speaker. House the circuits in separate small cabinets. If the transducer 40kHz under test is working, the receiver circuit generates loud whistle sound .

Ultrasonic Amplifier Circuit

Thus, this is all about ultrasonic transmitter and receiver. We hope that you have got a better understanding of this concept. Furthermore, any queries regarding this concept or engineering project ideas for final year engineering students, please approach us by commenting in the comment section below. Here is a question for you, what are the applications of ultrasonic proximity sensor?

Photo Credits:

• Ultrasonic Transmitter and Receiver by sensorwiki
• Ultrasonic Proximity Sensor by lamonde
• Ultrasonic Transmitter by blogspot