Using a Small Transformer to Step Up Piezo Transducer

[jeromekang]

Hi I want to step up the voltage of my piezo transducer which I tested to produce around 150+ mV. I need to step up the AC Voltage to around 2.5 V AC. I was advised that I can do that by using a small transformer.

My problem is, what kind of transformer would be applicable? Or how would I be able to determine the right transformer given I know the frequency of my piezo transducer? Any commercial ones I can buy?

 

[IanP]

Beacause of high output impedance of piezo transducer transformer as an amplifier is not a good option ..
Instead consider an opamp based amplifier and more info you can find in this appnote:
Signal Conditioning Piezoelectric Sensors
https://focus.ti.com/lit/an/sloa033a/sloa033a.pdf

IanP

 

[keith1200rs]

I guess it depends on the application. For power harvesting then a transformer would be a solution. Jeromekang needs to supply more details!

keith.

 

[jeromekang]

hi keith, yes the application is for energy harvesting specifically with keyboard presses and mouse clicks.

 

[keith1200rs]

You might find some useful information here:

Linear Technology - Energy Harvesting

In general, search for piezo energy harvesting.

Keith.

 

[jeromekang]

we have the LTC3588-1 since it is a complete energy harvesting solution. the problem is that we tested it with a DC power supply and needed at least 6v to power that's why we were recommended to use a transformer to boost the output of the energy mechanism to that amplitude. I've also emailed their technical assistance of this issue last week and still haven't got back to me yet.

 

[keith1200rs]

The piezo is supposed to be a high impedance, high voltage source. You seem to be getting a rather low voltage out of it. I am not sure a transformer would be practical as it would load the piezo, but I may be wrong. It may be worth concentrating on fixing the piezo voltage problem directly - something doesn't sound right (or you are simply expecting too much from your system design i.e. there just isn't enough energy available).

Keith.

 

[FvM]

or you are simply expecting too much from your system design

I fear the same. As a first step, I suggest to determine the available power from your piezo transducer. It can be done at any output voltage, just varying the load resistance until the maximum power is achieved. Then you can calculate an optimal conversion circuit.

 

[dick_freebird]

The question needs to comprehend the frequency band of
the energy being picked up. A transformer may be high
enough impedance, or not, depending on that frequency
and its primary, open-secondary inductance.

A good model of the piezo element's open-circuit and
short-circuit (or, say, 1 ohm) output in the environment
of interest, would do you a lot of good both conceptually
and in sorting out such details.