Need Help Finding Cheap Vibration Testing Equipment

[hiimjane]

Hi PF,
I hope I'm doing this right, first post. I need help with a research project for the effect of the ambient vibration frequency at resonance for a piezoelectric energy harvester (It's well documented, I know, but I have to do an experiment with it anyways).

Anyways, I noticed that vibration shakers are EXTREMELY expensive. I was looking for a cheap one that could do a basic frequency sweep from around 0-1000 Hz so I could find the resonance of the piezoelectric. The ones I found were over $5,000, which is way too much for me. Specific models of cheap ones would be SUPER helpful.

Also, I could use some help finding software that would measure the displacement and power output as well as something that could help me find the best matching resistor. Remember that I'm on a budget here...

Thanks!
Jane

 

[Tom.G]

A loudspeaker makes a shake table for lightweight items.

If you don't want to damage the speaker, stretch a thin rubber sheet over it, or some plasticwrap from the kitchen, and glue the piezo device to its center.
Watch out for the resonance of the speaker though. It's generally below 200Hz, and for 8-inch and larger speakers below 50Hz isn't unusual.

For matching resistor selection probably a Resistance Substitution Box is your best bet. The cheap ones (<$10 US the last time I looked) look like a hockey puck with two wires with clips coming out of them.

Can't think of a cheap, reliable way to measure displacement. Perhaps something optical, or even visual with a ruler.
Hopefully someone else on the site has something.

 

[hiimjane]

A loudspeaker makes a shake table for lightweight items.

I don't think I'd be able to do a reliable frequency sweep with a loudspeaker though, right?

 

[Tom.G]

I don't think I'd be able to do a reliable frequency sweep with a loudspeaker though, right?

Somebody here likely has another viable idea. What say folks?

EDIT: For software see post #5 at https://www.physicsforums.com/threa...-a-wine-glass-experiment.861560/#post-5416319

 

[hiimjane]

Somebody here likely has another viable idea. What say folks?

EDIT: For software see post #5 at https://www.physicsforums.com/threa...-a-wine-glass-experiment.861560/#post-5416319

Thanks, that should help with my oscilloscope. Speaking of, I know I can find the voltage using an oscilloscope, but how about current?

 

[berkeman]

I don't think I'd be able to do a reliable frequency sweep with a loudspeaker though, right?

As long as you can control the amplitude and frequency, you should be able to "level" the amplitude of the displacement. You might use a strobe light to help you see the extent of the vibration peaks.

 

[Tom.G]

I can find the voltage using an oscilloscope, but how about current?

If you know the voltage and the resistance then I=E/R; Amps = Volts/Ohms