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Piezoelectric transducers - help please

Hi all

Me and a friend are trying to power a lightbulb (albeit just flashes of light) using a cat. We figured that piezoelectric transducers would turn the pressure the cat exerts into electrical energy.

Maplin sell these transducers https://www.maplin.co.uk/p/3v-ceramic-piezo-transducer-2718-yu87u which we bought however after welding one to an LED no light is produced. Maplin sell these as devices which generate vibrations/sound from current but these should work both ways right?

On Google other people have used these transducers successfully to make shoes that charge phones so we believe this should work.

Any help is gratefully received.

Jack

Reply 1

Physics Enemy

I'm sure your cat appreciates being tested on, with the prospect of being electrocuted.

I've reported your post, I'm sure the mods and police can trace your IP easily enough.

Reply 2

stoyfan

Original post by jackhonour

Ok... Ummmm that is a pretty interesting project you got there.

Do you have a multimeter? If so, try to measure the voltage that it outputs when you apply pressure to it.

Original post by Physics Enemy

I'm sure your cat appreciates being tested on, with the prospect of being electrocuted.

I've reported your post, I'm sure the mods and police can trace your IP easily enough.

They are not looking to electrocuting the cat, you womble.

Their project doesn't involve passing current through a cat.

(edited 6 years ago)

Reply 3

peterdxherty

Original post by Physics Enemy

I'm sure your cat appreciates being tested on, with the prospect of being electrocuted.

I've reported your post, I'm sure the mods and police can trace your IP easily enough.

Your over reacting. What they're doing with electrocute the cat, it's essentially like a strap to put in the cat (made of rubber) which moves and send electricity through a wire. If it was dangerous then people wouldn't be trying to put it into clothes.

Reply 4

Physics Enemy

Original post by theeetimdoherty

If it was dangerous then people wouldn't be trying to put it into clothes.

Because people never do anything silly or with risk ...

Besides, the cat has no choice. I certainly don't want OP testing on me.

Reply 5

jackhonour

To clarify, the cat will not be strapped or have any risk of being electrocuted, The cat will stand on a wooden board and as it moves the transducers will be pushed down on by the wood. The cat's movement will not be restricted, and the cat will not be in contact with the transducers or any electrical components

Reply 6

jackhonour

Original post by stoyfan

Ok... Ummmm that is a pretty interesting project you got there.

Do you have a multimeter? If so, try to measure the voltage that it outputs when you apply pressure to it.

I don't have a multimeter, but guess I could buy one

Reply 7

stoyfan

Original post by jackhonour

I don't have a multimeter, but guess I could buy one

Yup, and this is a great time to learn about electronics. So look at youtube vids on beginner electronics.

The worry is that the piezo transducer might not be producing enough voltage to turn on the led.

The voltage required to turn on an led is called the forward voltage. What you should look into are Reed switches.

These switches let current to pass through if it detects a magnetic field, so all you need to do is to attach a magnet to the collar and connect a 3v battery and a 150 ohm resistor to the led.

Reply 8

jackhonour

Original post by stoyfan

The problem with that setup is that we aren't actually generating electricity. The wonderfulness of the piezo transducer was that the cat ITSELF was powering the lightbulb!!!!!

Reply 9

Joinedup

Never tried it but I'm pretty dubious about getting a useful amount of phone charging current out of a shoe. it's quite easy to get the charging indicator on a phone to come on at a very low current - doesn't mean it's doing anything very useful.

might be that the piezo is only producing enough current to light the LED dimly - so maybe if you tapped it with a pen or similar object in a darkened room?

Reply 10

Big_Jon

Some piezo electric buzzer have drivers in them. Because back in the day you had to apply a oscillating waveform on to the buzzer to make it buzz, now you just supply them with a DC voltage. So you need a raw peizoelectric component.

Reply 11

Joinedup

Original post by Big_Jon

looks like he's got the type you need to put a audio frequency square wave across from the link.

might also be worth trying a red LED if you haven't already - they've got the lowest Vf of any visible colour.