I am using 10 simple Piezo-sensors and providing the input to a schottky bridge rectifier which is then connected to a Boost converter to produce voltage to store in a battery. I understand that Boost converter needs high current and hence if possible I would really appreciate any simple alternative which uses commonly available components.

 

Not to dissuade you with this project but keep this in mind. You get very little power out of a piezo transducer and even with ten such sensors you have very little times ten which is still not enough power to do much let alone charge a battery. Something else to consider is to get the optimum output from a piezo transducer you need a mechanical input having the same frequency as the resonant frequency of your traducer(s). The transducers would also all need to be in sync so as the voltage from one is not opposing the voltage of the next. The few I have laying around, open circuit (working into a 10 Meg Ohm probe) produce about a 4 volt peak signal with a mild tap. Placing a load on them the output drops real quick, even with a 100K load. They work well as a sensor but not very well at all as a power source. I do not see any success with trying to charge a battery. However, if you wish to pursue this I would suggest you see what you actually have as to power.

If you have a dual channel scope you may wish to try this. Place two 1K Ohm resistors in series as a load. Place the 2 K Ohm load across your piezo output. Place the scope channel 1 across the load (piezo output) and place the channel 2 input at the junction of the two resistors. This gives you a voltage signal on channel 1 and a current signal on channel 2. A popular method here is to list the recorded signal values into Excel or other similar spreadsheet software. Let the software apply Ohms Law and note what the current is.

I believe when all is said and done you will find it is not practical to try and charge a battery using a piezo as a power source.

You may also want to give this a read.

Ron

 

Thanks for the reply.
I searched for some alternative solution. If not charging a battery, can I get a considerable amount of output voltage by allowing piezo voltage to get stored in a capacitor after passing it through a bridge rectifier so that I can use this voltage to pass a current from some load (say LED)?

 

Thanks for the reply.
I searched for some alternative solution. If not charging a battery, can I get a considerable amount of output voltage by allowing piezo voltage to get stored in a capacitor after passing it through a bridge rectifier so that I can use this voltage to pass a current from some load (say LED)?

If you want to try doing it then give it a try. Nothing to lose by trying it. I just don't see it working well for the reasons I mentioned but go ahead and try it. Maybe some other members have some thoughts to share?

Ron

 

If not charging a battery, can I get a considerable amount of output voltage by allowing piezo voltage to get stored in a capacitor

Capacitors store energy. Charging a capacitor and charging a battery are somewhat similar in that both involve a charging current and a rising voltage. There's so little energy available from the piezos, and very little current possible because of their inherent resistance, that a battery or capacitor of any decent mAh capacity.capacitance will take AGES to charge up.

 

What is the application? Can you use solar cells?
Why piezo?
Without exciting them at their resonance, just using ambient noise, you probably would not even beat battery self discharge current.

 

I have dim memory of a paper describing a peizo crystal that was driven by a transducer at one end and power at a higher voltage was taken from a transducer at the other end (I imagine the construction was similar to that of a glass delay line) to drive a florescent backlight.