Current drain: 220mA average at 12V driving a 3nF loadĪll of this still has me curious.Signal burst period: 600ms at 20kHz, 300ms at 40kHz (12000 cycles/ burst).

Frequency sweep in each band: 12 frequencies ranging from 80Hz spacings at 20kHz to 344Hz steps at 40kHz.

Output frequency range: 19.08 - 41.66kHz in 14 bands with 200ns steps.

Could be powered by a solar panel/wind generator.

Works with aluminium and fibreglass boats (not suitable for timber, ferro cement or fibreglass foam sandwich construction).

This design was also made into a product on a website 'Jaycar' with specifications listed as: Part 2: Ultrasonic Antifouling System – Part 2, Fighting Algae Growth | Nordkyn Design They go into some brief detail of the programmatic operation explaining that the drive is done in short pulses. Hey TomGeorge, that's a great find and really helpful! I found a great blog post where someone had built this circuit but had added support for an additional transducer. It's sealed so I don't know anything about the electronics but it runs from a 12VDC (maybe 10A?) power supply so there is no 'direct' connection to the power line.

It can get tricky with sine & square waves but 36V into a bridge driver is +36V half the time and -36V half the time so it's the same amount of power/energy as 36VDC and the straightforward V 2/R calculation works (ignoring the slight voltage-loss across the bridge driver and assuming a resistive load).

And, I don't know where you'd find the special high-frequency transformer with the 'right' impedance ratio. But obviously there is a resistive component to the transducer because it has to consume power to convert electrical energy into mechanical energy to 'do work'. with 20 Ohms of pure capacitive reactance (or any pure capacitive reactance) the voltage & current would be out-of-phase and no power would be consumed by the transducer. A piezo transducer has a large capacitive component and pure capacitance doesn't dissipate any power. The tricky part could be the complex impedance of the load. Your calculations are correct* (for a resistive load) and if the manufacturer's specs say 10-20 Ohm's I'd believe that. I've calculated 32v to drive a 50w 20ohm impedance load, but in most applications, the same or similar transducers with equally matched specifications are driven at nearly 10x that voltage. Nearly all of the circuits I've found, and all the applications I've found (for both ultrasonic cleaners and anti-fouling) are using transformers to directly drive a transducer at (as quoted from one source) '250VAC (about 700V peak-to-peak)'.įorgive me but I have no experience with piezoelectric transducers or AC circuits in general, and it frankly seems I'm overlooking something. However, after much time spent on Google, I'm beginning to second guess this approach and am more confused than ever. I had originally determined to step-up the voltage to 36v and then use an H-Bridge gate driver IC to drive a transducer at resonance with a 40khz square wave. In determination of the drive voltage required, and conservatively using the 20 ohm upper-end of the rated resonate impedance, Watts Law states that the voltage required to drive the transducer at 50w is just under 32v. The specifications also state that at resonance, this transducer presents a 10-20 ohm impedance (this is pretty much the average resonant impedance for most of these transducers). I have acquired transducers spec'd at a 40khz resonate frequency and 50w operating power consumption.

The same transducers are also used in industrial tank, reservoir, and boat hull anti-fouling applications (this latter application is what I'm interested in). These transducers are most abundantly found in ultrasonic cleaning equipment. I would like to receive clarification and opinions on driving bolt clamped (Langevin) piezoelectric transducers.

Piezo transducer