Possibly (probably) a dumb idea - compliant mechanism PCB's?

[drdn0]

I've had this idea floating around in my head for a bit, and I've spent a couple of hours doing some Googling with no success.

I've been going down the stompbox-sized micro synth wormhole after finding somebody local to talk stompbox design/DIY effects with, and I've put together a 1590B-sized Stepped Tone Generator with an inbuilt speaker that I'm waiting on PCB's for for him. He sent me a link to somebody who made a STG onto a 'business card', but it needed to be wired with speakers/power/etc; a cool idea, but the fact you need to solder a bunch of stuff to it before it actually makes noise takes all the fun away.

This got me thinking - I've also made a bunch of ambient noise generators with random pieces of junk and piezo contact mics, but I know they also work in the opposite direction AND can be driven directly by a 555.



So my question is this - has anybody ever seen, or tried, attaching a piezo transducer DIRECTLY to a PCB, and using that as the vibrating surface that makes sound? My assumption would be that there needs to be some sort of compliance between the surface that the piezo is attached to and the rest of the PCB in order to prevent dampening the moment it's touched, so the second question is has anybody built some sort of compliant mechanism into a PCB?

I'm definitely not expecting any sort of amazing sound quality, and with how annoying it's going to sound it doesn't need to be particularly loud.

Thankyou for entertaining these ridiculous ideas.

[DIY Bass]

I have seen piezo speakers direct soldered to PCBs pretty commonly.  The beepers on a multimeter continuity test are usually piezo and soldered direct to the PCB.  As long as you have a speaker, rather than a buzzer you should be right unless I completely misunderstand you.

[drdn0]

I have seen piezo speakers direct soldered to PCBs pretty commonly.  The beepers on a multimeter continuity test are usually piezo and soldered direct to the PCB.  As long as you have a speaker, rather than a buzzer you should be right unless I completely misunderstand you.

Basically - I want to mount a piezo element DIRECTLY to the PCB, with the PCB as the vibrating component of the speaker instead of having a standalone, separate speaker soldered onto the PCB.

Unnecessary? Absolutely. If it works would it be novel as anything? Absolutely

[stallik]

They're really inexpensive and I'm sure you must have a piece of scrap pcb board around so why not try it?

I know that when using a piezo disk as a microphone for a stomp box, the mounting method vastly alters bass response. Wonder if it's the same when it's used as a speaker?

I'm imagining that, at the very least, you'd need a hole on the pcb behind the disk to prevent it damping out. Perhaps glue a big rubber washer on the board and then glue the disk over that? Coil the hook up wire to save some strain on the pads

Let us know if we can all ditch the 4x12's 

[drdn0]

They're really inexpensive and I'm sure you must have a piece of scrap pcb board around so why not try it?

I know that when using a piezo disk as a microphone for a stomp box, the mounting method vastly alters bass response. Wonder if it's the same when it's used as a speaker?

I'm imagining that, at the very least, you'd need a hole on the pcb behind the disk to prevent it damping out. Perhaps glue a big rubber washer on the board and then glue the disk over that? Coil the hook up wire to save some strain on the pads

Let us know if we can all ditch the 4x12's 

I'd actually been waiting a couple of weeks for some eBay specials to turn up, and they finally did today.

Basically, even driving them with a 20v p2p signal, they're not really loud enough to be useful. They are audible (and a PCB does vibrate enough to amplify them), but not enough to do what I wanted to do with them.