# Help with driver circuit for ultrasonic piezoelectric speaker

#### hiya1432

Joined Jan 30, 2012
3
Hi this is my first post so i'll try to be detailed.

For a school project I'm looking to make a circuit that will amplify a 58-60 kHz signal to be sent to a piezoelectric speaker (datasheet for the speaker is here http://futurlec.com/USTR60-10H.shtml).
My team has already made a circuit for the oscillator by using 555's, so I'm just wondering about amplifying the signal so it can be used properly by the speaker. We're working with a 9v battery and I was wondering the best way to complete this. I know in the speaker datasheet it has a test circuit, but I was also wondering if there is a way to design a circuit without a transformer. If not could someone recommend a specific one that could be used on a breadboard.

Sean

#### mcasale

Joined Jul 18, 2011
210
I've never used a speaker like the one you have here, but just assume right now it's just a capacitive load (1600pF). At 60KHz, that translates to a 1.66K Ohm impedance. If you drive it with a 9V square wave, that means you need to source 5.4mA from the electronics.

So, depending on what signal you want to send to the speaker, you may only have to buffer the 555 output.

You need to be more detailed in what you want to send to the speaker (amplitude, sine or square waves). I'd think that driving square waves into a capacitive load can create some annoying current spikes.

#### hiya1432

Joined Jan 30, 2012
3
We're trying to have the speaker send out a 60 kHz signal (rectangular or sine wave) to three other receivers. The receivers only need to acknowledge that a signal was received because we are ordering the receivers from closest to furthest from the speaker based on which receives the signal first.

#### Audioguru

Joined Dec 20, 2007
11,249
The transformer steps up the voltage 7 times and since it is tuned with the capacitance of the piezo it steps up the voltage much more. Then the signal from the piezo is much higher than without the transformer so its range is much farther.

#### PaulEE

Joined Dec 23, 2011
423
We're trying to have the speaker send out a 60 kHz signal (rectangular or sine wave) to three other receivers. The receivers only need to acknowledge that a signal was received because we are ordering the receivers from closest to furthest from the speaker based on which receives the signal first.
If you can use different ultrasonic transducers, I would suggest you do so.

I ordered a few of these awhile back and they were complete junk...maybe I didn't have enough voltage on them, but they wouldn't do a thing for me. (exact model, exact site)

Let me know how it works out if you do get the things to function.