Piezoelectric air pump

[amdx]

Big Clive did a tear down of a Piezoelectric Aquarium air pump.
I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to 30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
Anyone care to enlighten me.
> https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

Thank you, Mikek

 

[Clive Arthur]

On 10/11/2019 15:50, amdx wrote:

Big Clive did a tear down of a Piezoelectric Aquarium air pump.
 I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
 I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
 Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

               Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz. The given 0.45 l/min is then
150ul/cycle or 150mm^3/cycle.

The disk is maybe 30 mm diameter which is 700 mm^2 so it would have to
move 0.2 mm or +/- 0.1 mm every cycle.

Double that to allow for losses and it still seems very reasonable.

Fun to play with these disks - I don't know why there aren't piezo
electric relays (or maybe there are?), once moved they take very little
power to hold.

Cheers
--
Clive (not that one)

 

[Clive Arthur]

On 10/11/2019 17:09, amdx wrote:

On 11/10/2019 10:35 AM, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

Double that to allow for losses and it still seems very reasonable.

Fun to play with these disks - I don't know why there aren't piezo
electric relays (or maybe there are?), once moved they take very
little power to hold.

Cheers

 Why would the 150uh inductor with 47 milliohms of reactance (50hz) be
there?

                                       Mikek

At a guess, along with the 10 nF capacitor it helps to stop mains
electrical noise from making it acoustically noisy.

It's probably not an optimal design, but a design using parts which were
at the time available for minimal cost.

Cheers
--
Clive

 

[amdx]

On 11/10/2019 10:35 AM, Clive Arthur wrote:

On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is then
150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have to
move 0.2 mm or +/- 0.1 mm every cycle.

Double that to allow for losses and it still seems very reasonable.

Fun to play with these disks - I don't know why there aren't piezo
electric relays (or maybe there are?), once moved they take very little
power to hold.

Cheers

Why would the 150uh inductor with 47 milliohms of reactance (50hz) be
there?

Mikek

 

[amdx]

On 11/10/2019 11:27 AM, Clive Arthur wrote:

On 10/11/2019 17:09, amdx wrote:
On 11/10/2019 10:35 AM, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

Double that to allow for losses and it still seems very reasonable.

Fun to play with these disks - I don't know why there aren't piezo
electric relays (or maybe there are?), once moved they take very
little power to hold.

Cheers

  Why would the 150uh inductor with 47 milliohms of reactance (50hz)
be there?

                                        Mikek

At a guess, along with the 10 nF capacitor it helps to stop mains
electrical noise from making it acoustically noisy.

It's probably not an optimal design, but a design using parts which were
at the time available for minimal cost.

Cheers

That was another thought I had, 50 Hz about 2 watts on the driver, why
was it very, very quiet, no 50 hz?

Mikek

 

[Clifford Heath]

On 11/11/19 3:35 am, Clive Arthur wrote:

On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is then
150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have to
move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way valve?
Because that valve has to open and shut, which involves some back-flow,
perhaps significant with such a small displacement. How is the valve
constructed, is it just a ball on a seat?

Clifford Heath.

 

[Clive Arthur]

On 10/11/2019 19:26, amdx wrote:

On 11/10/2019 11:27 AM, Clive Arthur wrote:
On 10/11/2019 17:09, amdx wrote:
On 11/10/2019 10:35 AM, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

Double that to allow for losses and it still seems very reasonable.

Fun to play with these disks - I don't know why there aren't piezo
electric relays (or maybe there are?), once moved they take very
little power to hold.

Cheers

  Why would the 150uh inductor with 47 milliohms of reactance (50hz)
be there?

                                        Mikek

At a guess, along with the 10 nF capacitor it helps to stop mains
electrical noise from making it acoustically noisy.

It's probably not an optimal design, but a design using parts which
were at the time available for minimal cost.

Cheers

 That was another thought I had, 50 Hz about 2 watts on the driver, why
was it very, very quiet, no 50 hz?

                        Mikek

Well, this is a bit outside my area, but it's a small pump, not a bass
reflex cabinet. I guess you're not going to couple much 50 Hz energy to
the air. Press one against your ear and you'd hear it.

Cheers
--
Clive

 

[amdx]

On 11/10/2019 2:56 PM, Clifford Heath wrote:

On 11/11/19 3:35 am, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way valve?
Because that valve has to open and shut, which involves some back-flow,
perhaps significant with such a small displacement. How is the valve
constructed, is it just a ball on a seat?

Clifford Heath.

It is an aquarium AIR pump.
Click on the link, he's shows the valves.
It rubber with a hole in one end and a cut on the other end.
Positive pressure blows the flaps open on the cut end, but a negative
pressure seals them shut.

Mikek

 

[Rick C]

On Sunday, November 10, 2019 at 3:56:57 PM UTC-5, Clifford Heath wrote:

On 11/11/19 3:35 am, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is then
150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have to
move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way valve?
Because that valve has to open and shut, which involves some back-flow,
perhaps significant with such a small displacement. How is the valve
constructed, is it just a ball on a seat?

The rubber flap *is* the valve. When air pushes on it, it opens. When the air pushes back it closes.

Lawn mowers use a flap in the gasket to create a flap valve so the vacuum pulses of the engine pull the gas up from the tank. When this valve starts to leak the valve will have back flow leakage and if the tank isn't nearly full it won't start. If you prime it enough it will start and continue to run, but may stop before the tank is empty.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Sunday, November 10, 2019 at 8:12:38 PM UTC-5, Clifford Heath wrote:

On 11/11/19 10:07 am, amdx wrote:
On 11/10/2019 2:56 PM, Clifford Heath wrote:
On 11/11/19 3:35 am, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way
valve? Because that valve has to open and shut, which involves some
back-flow, perhaps significant with such a small displacement. How is
the valve constructed, is it just a ball on a seat?

Clifford Heath.

 It is an aquarium AIR pump.

Apologies for not reading carefully.
The air flaps still take some finite amount of air to open and close,
even if they don't leak as well, that still affects efficiency.

You mean like in every diode ever built? Nothing is perfect. Why are you worried about something so unimportant?

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Clifford Heath]

On 11/11/19 10:07 am, amdx wrote:

On 11/10/2019 2:56 PM, Clifford Heath wrote:
On 11/11/19 3:35 am, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way
valve? Because that valve has to open and shut, which involves some
back-flow, perhaps significant with such a small displacement. How is
the valve constructed, is it just a ball on a seat?

Clifford Heath.

 It is an aquarium AIR pump.

Apologies for not reading carefully.
The air flaps still take some finite amount of air to open and close,
even if they don't leak as well, that still affects efficiency.

Clifford Heath.

 

[Clifford Heath]

On 11/11/19 12:14 pm, Rick C wrote:

On Sunday, November 10, 2019 at 8:12:38 PM UTC-5, Clifford Heath wrote:
On 11/11/19 10:07 am, amdx wrote:
On 11/10/2019 2:56 PM, Clifford Heath wrote:
On 11/11/19 3:35 am, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way
valve? Because that valve has to open and shut, which involves some
back-flow, perhaps significant with such a small displacement. How is
the valve constructed, is it just a ball on a seat?

Clifford Heath.

 It is an aquarium AIR pump.

Apologies for not reading carefully.
The air flaps still take some finite amount of air to open and close,
even if they don't leak as well, that still affects efficiency.

You mean like in every diode ever built? Nothing is perfect. Why are you worried about something so unimportant?

Worried? Not me. Just interested in the (in-)efficiency and the reasons
for it. It's a very small displacement - like a diode trying to rectify
a very small signal, it doesn't always work very well. Apparently well
enough, though.

 

[Rick C]

On Sunday, November 10, 2019 at 11:41:22 PM UTC-5, Clifford Heath wrote:

On 11/11/19 12:14 pm, Rick C wrote:
On Sunday, November 10, 2019 at 8:12:38 PM UTC-5, Clifford Heath wrote:
On 11/11/19 10:07 am, amdx wrote:
On 11/10/2019 2:56 PM, Clifford Heath wrote:
On 11/11/19 3:35 am, Clive Arthur wrote:
On 10/11/2019 15:50, amdx wrote:
Big Clive did a tear down of a Piezoelectric Aquarium air pump.
  I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
  I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to  30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
  Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

                Thank you, Mikek
No tuning or resonance, the disk is flexing at 50 Hz mains frequency.

One minute gives you 3000 cycles at 50 Hz.  The given 0.45 l/min is
then 150ul/cycle or 150mm^3/cycle.

The  disk is maybe 30 mm diameter which is 700 mm^2 so it would have
to move 0.2 mm or +/- 0.1 mm every cycle.

It that based on how much water it has to push through a one-way
valve? Because that valve has to open and shut, which involves some
back-flow, perhaps significant with such a small displacement. How is
the valve constructed, is it just a ball on a seat?

Clifford Heath.

 It is an aquarium AIR pump.

Apologies for not reading carefully.
The air flaps still take some finite amount of air to open and close,
even if they don't leak as well, that still affects efficiency.

You mean like in every diode ever built? Nothing is perfect. Why are you worried about something so unimportant?


Worried? Not me. Just interested in the (in-)efficiency and the reasons
for it. It's a very small displacement - like a diode trying to rectify
a very small signal, it doesn't always work very well. Apparently well
enough, though.

Seems to me to work just fine. I think your knowledge of the valve you seem to think is "inefficient" works just fine. I have no idea what your metric for "working well" is. Every check valve has back flow. This one seems to be pretty well suited for moving air.

--

Rick C.

-- Get 2,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[nuny@bid.nes]

On Sunday, November 10, 2019 at 7:50:19 AM UTC-8, amdx wrote:

Big Clive did a tear down of a Piezoelectric Aquarium air pump.
I want to know is the piezo actually flexing at 50Hz.
Or is something else going on.
I don't know the capacitance of the piezo, but If I were to
make a WAG, I'd say 8000pf to 30,000pf. That said the tuning (?)
inductor is 150uH, nowhere near enough to tune down to 50Hz.
Anyone care to enlighten me.
https://www.youtube.com/watch?v=hKsZUuvtylE&t=481s

He did a couple of videos on different brands which had nearly identical
guts. The L was also in series with a cap, both in parallel to the element. Their Fres was ~13 kHz IIRC.

Clive said he could hear the pump humming, not whining.

Clive opined that the L and C were there to keep line spikes and other
noise away from the piezo element, not to tune to its resonant frequency,
which makes sense.


Mark L. Fergerson

 

[Piotr Wyderski]

Clive Arthur wrote:

Well, this is a bit outside my area, but it's a small pump, not a bass
reflex cabinet.  I guess you're not going to couple much 50 Hz energy to
the air.  Press one against your ear and you'd hear it.

But then what is this pulsating air stream from the pump if not coupling?

Best regards, Piotr

 

[Rick C]

On Friday, November 15, 2019 at 4:43:03 AM UTC-5, Piotr Wyderski wrote:

Clive Arthur wrote:

Well, this is a bit outside my area, but it's a small pump, not a bass
reflex cabinet.  I guess you're not going to couple much 50 Hz energy to
the air.  Press one against your ear and you'd hear it.

But then what is this pulsating air stream from the pump if not coupling?

Best regards, Piotr

The air stream doesn't couple to the outside, it in fact, is buffered and smoothed by the capacitor like chamber that is mentioned in the video just so it doesn't couple to the outside air. I suspect they also want to maintain a steady pressure on the aerator so water doesn't come into the unit.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209