Inside a near-silent piezoelectric air pump. 

love it made me laugh

Thought that was what he said...... More commonly known as duck bill valve! 😂

It made me laugh too - until I remembered I sent my mates 11 year old son (who loves taking things apart) a link to this channel a few months back. He loves the channel so would have seen this by now. I might have to have a talk with him....

Has Clive just lost his female viewers?

I laughed :-D

Would need to convert displacement into significant rotation for a usable effect, but this is effectively what digital projector micromirrors do although I think they are electrostatically operated.

Viewing the signal with an Oscilloscope would be helpful.

I wanted to see how well it worked when the stone end was submersed

Justin Richards When you were stoned and submerged in what exactly ?

@@kissingfrogs ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ydoKydWKjK8.html

It may have been for a series capacitor, but they might have found that the piezo disk was oversensitive to transients with a capacitor in series.

At least that explains the discharge resistor. Funny that they still bothered to populate it.

I'm glad I'm not the only one who noticed that :P

I did and it seemed to work.

That's a brilliant tip. Does any alcohol work.....IPA or do I have to dip into my whiskey stock?

John Carr IPA works brilliant don't know about others

John Carr IPA works, haven't found ethanol to work quite as well.

Ethanol works great. But you have to drink a lot.

Yeah I'd suspect so & I'd guess the most annoying noise would be from the valves snapping shut rather than the diaphragm, that was the case on an old school aquarium pump I took apart in my youth.

Old buildings used 70.7 volt systems for distributing audio over wide areas, and transformers to step the audio voltage up and down for 8 or 16 ohms. That kind of audio transformer would work well for this test if a pair of the transformers was put in parallel on the 8 ohm side, and in series on the 70.7 volt side.

or you could fill a balloon for 1 minute and check its volume by immersing it in water

I'm under the impression that most manufactured disks do rely on setting a charge thermally. The water atomiser disks certainly lose their ability to function if they are operated dry and heat up to their Curie point.

This certainly might be the case... Just wanted to stress that for the piezoelectric materials this thermal procedure is optional. Anyway, thanks for the video, very interesting indeed.

YS akaYSembed Can the crystals be re-energised if they reach their curie point and fail?

Don't know for sure, but I guess that most probably this process is indeed reversible. Although I don't think that it is possible to restore that crystal at home (unless you're Ben Krasnow).

@@bigclivedotcom Thanks for the demonstration. How is piezo disk is air seal ? Is it just an adhasive or rubber gaske?

Yes but I’ve used pumps for out door fountains that make enough noise that you can hear it 10 ft away

And they have been about the same size if not a tiny bit bigger

Do R/C! Zzzapp, mmmmm pepperoni!

putana-electrico

Watch it, buster - that's my trademarked brandname for my toaster oven company.

Jafafa Hots I invoke fair use!

Use of these disks in ultrasonic mist makers always concerned me. Are they silent only because the noise they make is above human hearing? So are they doing the same thing to your brain that they do to the water -- atomising it, but in a way such that you don't notice. That his pump operates at line frequency is reassuring.

Good question as I was wondering the exact same thing for my miniature bagpipes as well.

Put an audio signal directly into the pump.

Bagpipe lullaby.

I wonder if they have a larger size as I use an aquarium pump as my air assist on my laser machine and it is louder than the screams from hell. Something around 50l a minute is needed.

Get a few of them

They aren't additive like that.

Sure they are. You would just need about 111 of them @ 0.45 lpm in parallel to get your 50 lpm. Of course the noise would be additive, too. There are lots of other pumps that might do what you need. Industrial and medical surplus suppliers always have odd air pumps.

Due to the nature of the mechanism, they're only rated for tanks up to 45l in volume, it's unlikely piezoelectric would work well with larger tanks due to the difference between the air pressure produced and the water pressure at the lower depths, unless you only wanted to run it nearer the surface.

You are technically correct. Which is the best kind of correct :)

Quality post, mon ami.

Find a screw on wire cap that is about the same size as the hose. Drill a hole in the small end and another hold halfway on the side. Screw it onto the hose end, feed another hose in the hole you drill on the side. That small hose should pull a vacuum via Venturi effect.

Or less as the valves physically need time to move. And yet worth a try

How about connecting the piezo via a bridge rectifier to get 100Hz? You're in with a decent chance that the valves fitted would cope with that. But with the same power input you'll get a smaller excursion of the piezo so you want to increase that. Also the sound gets more noticeable at higher frequency.

+bigclivedotcom and Ray Kent -- When a piezoelectric crystal is given DC only, it deflects in one direction only, and stays that way until power (essentially just voltage) is removed. So you would have to make sure there was no capacitor storing DC. But the piezo device itself stores energy, and acts like a capacitor in that way. So I think you'd have to give a discharge path, maybe just a resistor, but probably some active circuitry with a transistor, though a mere NE2 neon light might do enough. What say, Clive?

YodaWhat I think that what you said is technically correct, but you're missing scale. Similar sized piezo elements are used for tweeters and beyond into ultrasound. That suggests that they have very low capacitance, though I can't give a figure offhand. If driven direct from a bridge rectifier the discharge is catered for by the reversal of current. It's true that there would be an average dc offset from that set-up, but a series capacitor and parallel resistor would deal with that, if needed.

Piezoelectric devices are modeled as a combination of inductor and capacitor, which both stores energy and resonates at a certain frequency. While they can work at other frequencies, efficiency is then lower. High-end audio equipment compensates for that by brute force: Shoving more watts at the tweeters. And it is always alternating current. The scale of the air pump device is actually far too small to resonate efficiently at either 50 or 60 Hz, and it shows no evidence of extra (vibrating) mass being added to lower the resonant frequency. So yes, on that front it would be better to use higher frequency. But it has to be AC, not DC. While a bridge rectifier receiving power through an AC-rated capacitor will give pulsating DC current to a load, it is not clear that this piezopump is enough of a load to get serious pulsation. If efficiency is ignored, a dummy load resistor across the piezo element could force the issue, of course, but it will certainly be inefficient. If Clive were inclined to re-engineer devices, I would suggest using the first harmonic at 150 Hz from a squared-off 50 Hz sinewave, or even a variable-frequency oscillator circuit. But there are other RU-vid channels for that kind of modifications.

I had a crystal earpiece too. They were useful for fault finding because of their high impedance.,

The modern equivalent in the sound industry is this neat signal tracing gadget:- www.vizear.com/

Thanks Clive. Interesting device.. (I also got looking at that Flame safe candle flame effect light on that link) . Sorry to go off the subject , but years ago I had dealings with a very "realistic" candle flame effect light , or lights , that used a "loose" incandescent bulb, shaped like a flame , that were gently moved by a coil (similar to those LED candles) . They were almost impossible to distinguish from a real candle , even close up. I have yet to see a modern version that comes as close to the real thing as those did.

John Francis Doe 120-240v :p

It appears to be flexing at mains frequency.

It's not a new idea. Somewhere I have an old piezo fan that powers directly from 240V and has two sections in series flapping plastic fins at high speed.

​@@bigclivedotcom Very early Macs had a piezo fan with wings, if not from the factory at least as after market.

The air valves would not be able to open and close at such a high frequency. The disk does seem to vibrate at mains frequency. One theory about the inductor and capacitor is that any mains borne noise would be made audible by the piezo disk like a speaker, and the filtering reduces that.

bigclivedotcom I agree that the valve probably doesn't rectify air at 100+kHz, but I don't believe it has to. Each time air does escape, the average pressure in the cavity will change, the speed of sound in the gaseous medium will shift slightly, and the point of peak constructive interference will move slightly. Likewise, the resonant frequency of the piezo element will shift slightly throughout the whole AC mains cycle as the amount of energy dissipated as heat or compressive work will rise by the square of the voltage and steal energy from the resonant system faster at peaks, correlating with a higher resonant frequency at higher voltage and lower frequency nearer to AC zero crossing cycles. My guess is the valve actually actuates at some integer fraction of the piezo disk's oscillation frequency and quite possibly, the valve never fully closes - instead becoming more and less flow restricting. The fact that the whole resonant system shuts down every AC input zero crossing can explain the audible noise at 100/120Hz without necessarily being meaningful at all towards the pumping mechanics. The easiest way to find out would be to put an oscilloscope across the capacitor and see if there is a high frequency riding on the slow AC mains carrier.

The solder paste dispensers require really high pressure to get reliable results.

Damn, I'm sure he already tried something like that already. Probably would have been better than the foot pump he used lol.

All hale the Hammer Of Knowledge!

Simon Ruszczak I bet Thor doesn't have X-ray on his hammer like Clive does :P

The Hammer of Vision.

I thought it was a copy that might not have had the original technology inside. So that was actual surprise when I saw the disk.