Controlling Aquarium Air Pump Output

[~misfit~]

Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have and thus
no longer need all of its output. Rather than swap to one of my smaller,
noisier and less relaible pumps I'd like to continue using the Hailea but
reduce its output (reducing its power draw would also be great).

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole of an
AC electromagnet.

I was wondering if something like this would do the job without damaging the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I think this is similar if not the same unit - I can't find the one Clive
reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx

Thanks in advance for any replies.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Computer Nerd Kev]

~misfit~ <shaun.at.pukekohe@gmail.com> wrote:

Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have and thus
no longer need all of its output. Rather than swap to one of my smaller,
noisier and less relaible pumps I'd like to continue using the Hailea but
reduce its output (reducing its power draw would also be great).

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole of an
AC electromagnet.

I don't know much at all about compressors, but it sounds like the effect of
using a phase angle controller would be to reduce the force the compressor
could pump at more than its speed. If it were a "rotary" compressor based
on a normal electric motor, the speed may decrease in better proportion.

I don't know enough about compressors and fish to know the implications of
this. At a guess - if you wanted to use the pump for fewer fish tanks, you'd
want the same pressure but less volume, so slowing the speed of the compressor
would be better than reducing its power. A similar device could be used to
reduce the speed by turning off for entire cycles of the AC mains instead of
a percentage of each cycle. Or perhaps a DC power supply and controller could
be used, alternating the polarity at a variable rate (a lower voltage would
be used than with an AC supply). I don't know if either of these things exist
as cheap "modules" (the latter, DC, option wouldn't likely be cheap in any
case).

I was wondering if something like this would do the job without damaging the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I haven't watched the video, but I believe I know the principal of the device
in the video's description. I don't imagine it could damage the pump, unless
perhaps the pump has its own circuitry that might be affected by inductive
pulses.

I think this is similar if not the same unit - I can't find the one Clive
reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx

I'd still strongly recommend closely examining any item that cheap and
Chinese before letting it anywhere near mains. Actually as a rule I
never use any cheap Chinese stuff from ebay with mains, but that's
just me.

--
__ __
#_ < |\| |< _#

 

[~misfit~]

Once upon a time on usenet Computer Nerd Kev wrote:

~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have
and thus no longer need all of its output. Rather than swap to one
of my smaller, noisier and less relaible pumps I'd like to continue
using the Hailea but reduce its output (reducing its power draw
would also be great).

The pump is the vibrator type. A permanent magnet attached to an
armature with diaphragm-type 'compressors' at each end moves from
pole to pole of an AC electromagnet.

I don't know much at all about compressors, but it sounds like the
effect of using a phase angle controller would be to reduce the force
the compressor could pump at more than its speed. If it were a
"rotary" compressor based
on a normal electric motor, the speed may decrease in better
proportion.

This youtube video shows a pump similar to mine, just a little bigger;
https://www.youtube.com/watch?v=ncnPMAWQfDQ

The reason that I'm so concerned about not damaging it is the pump was quite
expensive for me and I have the luck of a very unlucky thing. A wee while
back I needed a repair kit for it and had the devil's own job finding one -
I ended up buying a second-hand pump that had burnt out and using a valve
block from that on my pump. I'd like to keep it running as long as possible
as I can't afford a new one.

I'm worried that the essentially shorter pulses might cause more stress on
the components or maybe start harmonic vibrations? I don't know, just want a
more qualified opinion really.

I don't know enough about compressors and fish to know the
implications of this. At a guess - if you wanted to use the pump for
fewer fish tanks, you'd want the same pressure but less volume, so
slowing the speed of the compressor would be better than reducing its
power. A similar device could be used to reduce the speed by turning
off for entire cycles of the AC mains instead of a percentage of each
cycle. Or perhaps a DC power supply and controller could be used,
alternating the polarity at a variable rate (a lower voltage would be
used than with an AC supply). I don't know if either of these things
exist as cheap "modules" (the latter, DC, option wouldn't likely be
cheap in any case).

I was wondering if something like this would do the job without
damaging the pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I haven't watched the video, but I believe I know the principal of
the device in the video's description. I don't imagine it could
damage the pump, unless perhaps the pump has its own circuitry that
might be affected by inductive pulses.

I think this is similar if not the same unit - I can't find the one
Clive reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx

I'd still strongly recommend closely examining any item that cheap and
Chinese before letting it anywhere near mains. Actually as a rule I
never use any cheap Chinese stuff from ebay with mains, but that's
just me.

I always dis-assemble and check anything like this that's going to be used
on mains voltage. I don't trust my life to a minimum-wage foriegn person
assembling something that they likely don't even understand.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Computer Nerd Kev]

On 27 Mar 2016, ~misfit~ wrote:

Once upon a time on usenet Computer Nerd Kev wrote:
~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is
quiet and reliable. However I've reduced the number of
fish tanks that I have and thus no longer need all of its
output. Rather than swap to one of my smaller, noisier
and less relaible pumps I'd like to continue using the
Hailea but reduce its output (reducing its power draw
would also be great).

The pump is the vibrator type. A permanent magnet
attached to an armature with diaphragm-type 'compressors'
at each end moves from pole to pole of an AC
electromagnet.

I don't know much at all about compressors, but it sounds
like the effect of using a phase angle controller would be
to reduce the force the compressor could pump at more than
its speed. If it were a "rotary" compressor based
on a normal electric motor, the speed may decrease in
better proportion.

This youtube video shows a pump similar to mine, just a
little bigger; https://www.youtube.com/watch?v=ncnPMAWQfDQ

Next month. I just discovered I've got 3MB internet data left
for this month.

The reason that I'm so concerned about not damaging it is
the pump was quite expensive for me and I have the luck of
a very unlucky thing. A wee while back I needed a repair
kit for it and had the devil's own job finding one - I
ended up buying a second-hand pump that had burnt out and
using a valve block from that on my pump. I'd like to keep
it running as long as possible as I can't afford a new one.

I'm worried that the essentially shorter pulses might cause
more stress on the components or maybe start harmonic
vibrations? I don't know, just want a more qualified
opinion really.

Fair enough. The pulses won't damage the coil itself, but the
back EMF it will produce when suddenly turned off has the
potential to damage any electronics used in the pump (or the
controller, though it should be designed to handle it). Any
protection circuitry used may not have been designed to cope
with the high frequency of these inductive pulses due to the
rapid power switching.

I don't know about the mechanical side. My fear would more be
of some mechanical action not being reset if the coil is not
energised enough to complete a normal stroke. I doubt it's
that complicated, but I'm just guessing. Of course the
manufacturer would be the best to ask.

--
__ __
#_ < |\| |< _#

 

[~misfit~]

Once upon a time on usenet Computer Nerd Kev wrote:

On 27 Mar 2016, ~misfit~ wrote:

Once upon a time on usenet Computer Nerd Kev wrote:
~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is
quiet and reliable. However I've reduced the number of
fish tanks that I have and thus no longer need all of its
output. Rather than swap to one of my smaller, noisier
and less relaible pumps I'd like to continue using the
Hailea but reduce its output (reducing its power draw
would also be great).

The pump is the vibrator type. A permanent magnet
attached to an armature with diaphragm-type 'compressors'
at each end moves from pole to pole of an AC
electromagnet.

I don't know much at all about compressors, but it sounds
like the effect of using a phase angle controller would be
to reduce the force the compressor could pump at more than
its speed. If it were a "rotary" compressor based
on a normal electric motor, the speed may decrease in
better proportion.

This youtube video shows a pump similar to mine, just a
little bigger; https://www.youtube.com/watch?v=ncnPMAWQfDQ

Next month. I just discovered I've got 3MB internet data left
for this month.

Bugger! When you've got data this youtube video is of a pump made by the
same company as mine, mine's just a smaller model (30l/m as opposed to
60l/m) but construction of the pump is almost identical in all but
dimension.
https://www.youtube.com/watch?v=jeUMHOH31So
The video is of a guy trying to 3D print replacement parts for his as he
can't get spares either - and he's in the UK, not at the ends of the earth.
The flapper valves tend to 'go' first and my pump, being smaller than his
has glued-shut plastic tops of the valve chambers whereas his are metal and
held on by screws. For his there are supposed to be replacement flapper
valves avaiable whereas for mine the 'fix' is to fit a whole new valve
block - which isn't available here in NZ and I couldn't find anyone prepared
to ship one to me from Aus, EU, UK..... I fixed the last issue by
buying a second-hand one that had a burnt out electromagnet and using the
valve block from that. However they're not common second-hand so if it
happens again......

The biggest killer of these types of pump (at least the valves and
diapragms) is excess back pressure. Lifetime is shortened logrithmically in
relation to working pressure beyond their stated maximum. With the smaller
ones used in home aquaria the airstones they use get populated by aerobic
bacteria quite quickly and within six months or less they can increase
backpressure enough to destroy the pumps neoprene parts. I change my
airstones every three months and soak the used ones in bleach overnight then
rinse and store for the next change cycle.

The reason that I'm so concerned about not damaging it is
the pump was quite expensive for me and I have the luck of
a very unlucky thing. A wee while back I needed a repair
kit for it and had the devil's own job finding one - I
ended up buying a second-hand pump that had burnt out and
using a valve block from that on my pump. I'd like to keep
it running as long as possible as I can't afford a new one.

I'm worried that the essentially shorter pulses might cause
more stress on the components or maybe start harmonic
vibrations? I don't know, just want a more qualified
opinion really.

Fair enough. The pulses won't damage the coil itself, but the
back EMF it will produce when suddenly turned off has the
potential to damage any electronics used in the pump (or the
controller, though it should be designed to handle it). Any
protection circuitry used may not have been designed to cope
with the high frequency of these inductive pulses due to the
rapid power switching.

I've ordered one of the controllers - they take a while to arrive and even
if I don't use it for this I dare say I'll find a use for it some time. The
pumps themselves are 'dumb' - just a coil attached to the mains from what I
can tell. There's not even a switch. I guess then my question is a bit
outside of this newsgroups charter but I didn't know where else to ask a
question like this and I'd hate to (effectively considering the dearth of
parts) kill the pump.

I don't know about the mechanical side. My fear would more be
of some mechanical action not being reset if the coil is not
energised enough to complete a normal stroke. I doubt it's
that complicated, but I'm just guessing. Of course the
manufacturer would be the best to ask.

You'll see in the video/s when your data re-sets. It's just an armature that
oscillates in a magentic field at mains fequency attached to neoprene
diaphagms at each and which pump a small amount of air each stroke through
cicrular 'rubber' flapper valves which are held in their centres. I just
want to reduce the output of my pump without overstressing it.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Jasen Betts]

On 2016-03-27, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:

Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have and thus
no longer need all of its output. Rather than swap to one of my smaller,
noisier and less relaible pumps I'd like to continue using the Hailea but
reduce its output (reducing its power draw would also be great).

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole of an
AC electromagnet.

I was wondering if something like this would do the job without damaging the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I think this is similar if not the same unit - I can't find the one Clive
reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx

Thanks in advance for any replies.

s I unserstand is those things are resonant systems tuned to the
mains frequency, so anything that messes with the stroke frequecy
would require alteration of the pump to re-tune it. this pretty-much
leaves you with the only option being reducing the stroke length.

probably reducing the input voltage will do what you want. so a series
dropper of some sort, or a step-down transformer. you could try a fan
speed controller, or to test this out a 100w lamp.

--
\_(ツ)_

 

[Jasen Betts]

On 2016-03-28, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:

Once upon a time on usenet Computer Nerd Kev wrote:
block - which isn't available here in NZ and I couldn't find anyone prepared
to ship one to me from Aus, EU, UK.....

https://www.nzpost.co.nz/tools/youshop
"YouShop gives you delivery addresses on the ground in the UK (for
shopping across Europe), USA and China..." not free of course.


--
\_(ツ)_

 

[Clifford Heath]

On 28/03/16 15:40, Jasen Betts wrote:

On 2016-03-27, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable.

A small Variac would work but probably cost as much as a new pump.

What is its maximum power consumption? If it's only (say) 50W
you could operate it from an old audio amplifier with a simple
sinewave oscillator. Step up the output using a mains transformer
in reverse and use the volume control for speed.

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole of an
AC electromagnet.

Does the armature have any centering spring around which it oscillates?
If so, then Jason is right and it is resonant at somewhere near the
mains frequency. Changing the frequency will reduce the efficiency.

I was wondering if something like this would do the job without damaging the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

No - don't do that. A thyristor-based controller will mess with the
coils badly. You need a sine-wave power source.

As I understand is those things are resonant systems tuned to the
mains frequency, so anything that messes with the stroke frequency
would require alteration of the pump to re-tune it.

Yes, but the resonance is not very high-Q. The goal is to convert
the energy into compressed air, after all. Changing the frequency
if the Q is low will just reduce efficiency, but not catastrophically.

Clifford Heath.

 

[Clifford Heath]

On 29/03/16 12:32, John G wrote:
> The pump will only operate properly at its rated voltage and FREQUENCY

The OP doesn't want it to operate properly. He wants it to operate at
reduced output, cheaply. Stoopid ideas
yes, but the definition of "cheaply" depends on what he
has lying around and how he wants to use it.

Any reduction in voltage or change in frequency will reduce
efficiency - but not as much as bleeding of excess air will.

 

[~misfit~]

Once upon a time on usenet Jasen Betts wrote:

On 2016-03-27, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have
and thus no longer need all of its output. Rather than swap to one
of my smaller, noisier and less relaible pumps I'd like to continue
using the Hailea but reduce its output (reducing its power draw
would also be great).

The pump is the vibrator type. A permanent magnet attached to an
armature with diaphragm-type 'compressors' at each end moves from
pole to pole of an AC electromagnet.

I was wondering if something like this would do the job without
damaging the pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I think this is similar if not the same unit - I can't find the one
Clive reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx

Thanks in advance for any replies.

s I unserstand is those things are resonant systems tuned to the
mains frequency, so anything that messes with the stroke frequecy
would require alteration of the pump to re-tune it. this pretty-much
leaves you with the only option being reducing the stroke length.

They're hardly tuned per se. There's an armature made up of permanent
magnet (or two) in a light frame suspended between the electromagnet poles
attached at each end in the middle of a rubber diaphragm. As the AC
alternates and the elctromagent poles change the whole shebang moves
somewhere between 5 and 10mm each way. One-way rubber flapper valves let the
air in and out of the two diapraghm chambers.

As I understand it, going by what Clive says at the end of his teardown the
'speed controller' reduces the duration of the AC pulses. So it's still 50Hz
but instead of a sine wave the positive and negative pulses duration can be
modified to, for instance half of a sine wave with the remaining half flat
line - zero volts.

So for instance at 'half power' instead of 10ms of positive and 10ms of
negative it would be zero volts for 5ms, positive pulse for 5ms, zero volts
for 5ms, negative pulse for 5ms. At least that's how I understand it, I
could be wrong, this isn't my forte.

My hope is that this would result in the armature only getting half of the
motive force so only moving half as much (with the controller set at half
power). However it might instead pulse each way then return to centre
instead? Also I'm not sure what effect if any this type of 'peak duration
reduction' would have on the longevity of the electromagnet?

probably reducing the input voltage will do what you want. so a series
dropper of some sort, or a step-down transformer. you could try a fan
speed controller, or to test this out a 100w lamp.

I don't have any of the above.

Actually I may be able to dig out a 60 or 75 watt incandescant light bulb
from the back of the cupboard - I only use LED lamps in the house now,
swapped out the CFLs a while back. What would the effect of wiring an
incandescant bulb in parallel to the pump be? I mentioned I'm new to
electrical theory yes?

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[~misfit~]

Once upon a time on usenet Clifford Heath wrote:

On 28/03/16 15:40, Jasen Betts wrote:
On 2016-03-27, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable.

A small Variac would work but probably cost as much as a new pump.

Yeah. I'd love to own a variac but alas.....

What is its maximum power consumption? If it's only (say) 50W
you could operate it from an old audio amplifier with a simple
sinewave oscillator. Step up the output using a mains transformer
in reverse and use the volume control for speed.

It's 25W but that setup sounds compicated. I don't have a sinewave oscilator
either.

The pump is the vibrator type. A permanent magnet attached to an
armature with diaphragm-type 'compressors' at each end moves from
pole to pole of an AC electromagnet.

Does the armature have any centering spring around which it
oscillates? If so, then Jason is right and it is resonant at
somewhere near the mains frequency. Changing the frequency will
reduce the efficiency.

Please see my reply to Jason. No spring as such, the centering after pulses
is due to 'rubber' diaphragm suspension. Well I guess they *are* actually
acting as springs in this device but I doubt they'd have a similar sort of
resonant frequency as say a steel spring.

I was wondering if something like this would do the job without
damaging the pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

No - don't do that. A thyristor-based controller will mess with the
coils badly. You need a sine-wave power source.

Seriously? Damn.

As I understand is those things are resonant systems tuned to the
mains frequency, so anything that messes with the stroke frequency
would require alteration of the pump to re-tune it.

Yes, but the resonance is not very high-Q. The goal is to convert
the energy into compressed air, after all. Changing the frequency
if the Q is low will just reduce efficiency, but not catastrophically.

That's a bit beyond me... Or not if by 'Q' you mean resonant frequancy of
the armature assembly?

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[John G]

Clifford Heath was thinking very hard :

On 28/03/16 15:40, Jasen Betts wrote:
On 2016-03-27, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable.

A small Variac would work but probably cost as much as a new pump.

What is its maximum power consumption? If it's only (say) 50W
you could operate it from an old audio amplifier with a simple
sinewave oscillator. Step up the output using a mains transformer
in reverse and use the volume control for speed.

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole of
an
AC electromagnet.

Does the armature have any centering spring around which it oscillates?
If so, then Jason is right and it is resonant at somewhere near the
mains frequency. Changing the frequency will reduce the efficiency.

I was wondering if something like this would do the job without damaging
the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

No - don't do that. A thyristor-based controller will mess with the coils
badly. You need a sine-wave power source.

As I understand is those things are resonant systems tuned to the
mains frequency, so anything that messes with the stroke frequency
would require alteration of the pump to re-tune it.

Yes, but the resonance is not very high-Q. The goal is to convert
the energy into compressed air, after all. Changing the frequency
if the Q is low will just reduce efficiency, but not catastrophically.

Clifford Heath.

What a load of BS all these answers have been :-?
The pump will only operate properly at its rated voltage and FREQUENCY

The easy way is to just let the old delivery hoses dump to space or
even into the remaining tanks and adjust the various flows to do the
job lol
You do have taps on each these to adjust the flow,Don't You?

Too often we get these pie in the sky fixes that require the silliest
or unmanageble actions to acheive the simplest of tasks :-?

--
John G Sydney.

 

[~misfit~]

Once upon a time on usenet Jasen Betts wrote:

On 2016-03-28, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
Once upon a time on usenet Computer Nerd Kev wrote:
block - which isn't available here in NZ and I couldn't find anyone
prepared to ship one to me from Aus, EU, UK.....

https://www.nzpost.co.nz/tools/youshop
"YouShop gives you delivery addresses on the ground in the UK (for
shopping across Europe), USA and China..." not free of course.

Thanks, I'm aware of that (expensive) service. I should have been clearer -
not only couldn't I find anyone to ship the parts to me but I couldn't
actually find a supplier period. That's why the guy in one of the videos I
linked was 3D printing parts for his pump - he couldn't get parts either and
he's in the UK.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Clifford Heath]

On 29/03/16 16:53, ~misfit~ wrote:

Once upon a time on usenet Clifford Heath wrote:
Does the armature have any centering spring around which it
oscillates? If so, then Jason is right and it is resonant at
somewhere near the mains frequency. Changing the frequency will
reduce the efficiency.
Please see my reply to Jason. No spring as such, the centering after pulses
is due to 'rubber' diaphragm suspension. Well I guess they *are* actually
acting as springs in this device but I doubt they'd have a similar sort of
resonant frequency as say a steel spring.

Yup, not much resonance involved then. The "push" energy goes into
one cylinder and the "pull" energy the other; very little into any
energy storage (spring and mass).

Yes, but the resonance is not very high-Q. The goal is to convert
the energy into compressed air, after all. Changing the frequency
if the Q is low will just reduce efficiency, but not catastrophically.

That's a bit beyond me... Or not if by 'Q' you mean resonant frequancy of
the armature assembly?

Q is a ratio of the amount of energy circulating (stored in the moving
spring & mass in this case) divided by the amount of energy extracted
in each cycle. So if it's putting out 25 watts at 50 cycles per
second, each cycle puts out half a joule. If the spring/mass
oscillation stores (say) 10 joules, the Q is 20 (=10/0.5).

But your pump sounds like it has a Q of less than 1. Not resonant.
Probably operates exactly at mains frequency, and will probably
work at a lower frequency, producing less air volume. Just don't
feed it DC or the magnets will saturate and probably melt wires.
You really need an AC current source, enough to produce the correct
stroke at your desired power output.

 

[Clocky]

On 27/03/2016 8:03 AM, ~misfit~ wrote:

Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have and thus
no longer need all of its output. Rather than swap to one of my smaller,
noisier and less relaible pumps I'd like to continue using the Hailea but
reduce its output (reducing its power draw would also be great).

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole of an
AC electromagnet.

I was wondering if something like this would do the job without damaging the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I think this is similar if not the same unit - I can't find the one Clive
reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx

Thanks in advance for any replies.

No not really, it will just make it less efficient but not greatly so
before it just doesn't work.

What it needs is an air bleed to bleed off the excess air you don't want
I should think.

 

[~misfit~]

Once upon a time on usenet Clifford Heath wrote:

On 29/03/16 16:53, ~misfit~ wrote:
Once upon a time on usenet Clifford Heath wrote:
Does the armature have any centering spring around which it
oscillates? If so, then Jason is right and it is resonant at
somewhere near the mains frequency. Changing the frequency will
reduce the efficiency.
Please see my reply to Jason. No spring as such, the centering after
pulses is due to 'rubber' diaphragm suspension. Well I guess they
*are* actually acting as springs in this device but I doubt they'd
have a similar sort of resonant frequency as say a steel spring.

Yup, not much resonance involved then. The "push" energy goes into
one cylinder and the "pull" energy the other; very little into any
energy storage (spring and mass).

Yes, but the resonance is not very high-Q. The goal is to convert
the energy into compressed air, after all. Changing the frequency
if the Q is low will just reduce efficiency, but not
catastrophically.

That's a bit beyond me... Or not if by 'Q' you mean resonant
frequancy of the armature assembly?

Q is a ratio of the amount of energy circulating (stored in the moving
spring & mass in this case) divided by the amount of energy extracted
in each cycle. So if it's putting out 25 watts at 50 cycles per
second, each cycle puts out half a joule. If the spring/mass
oscillation stores (say) 10 joules, the Q is 20 (=10/0.5).

But your pump sounds like it has a Q of less than 1. Not resonant.
Probably operates exactly at mains frequency, and will probably
work at a lower frequency, producing less air volume. Just don't
feed it DC or the magnets will saturate and probably melt wires.
You really need an AC current source, enough to produce the correct
stroke at your desired power output.

Thanks for the reply and explaination.

So ideally a variac then - which I'd assumed and which I don't have.

Do you know if the device that I've ordered will hurt my pump? This is a
cut'n'paste of another post of how I understand it works:
------------------------
As I understand it, going by what Clive says at the end of his teardown the
'speed controller' reduces the duration of the AC pulses. So it's still 50Hz
but instead of a sine wave the positive and negative pulses duration can be
modified to, for instance half of a sine wave with the remaining half flat
line - zero volts.

So for instance at 'half power' instead of 10ms of positive and 10ms of
negative it would be zero volts for 5ms, (full voltage) positive pulse for
5ms, zero volts
for 5ms, negative pulse for 5ms. At least that's how I understand it, I
could be wrong, this isn't my forte.

My hope is that this would result in the armature only getting half of the
motive force so only moving half as much (with the controller set at half
power). However it might instead pulse each way then return to centre
instead? Also I'm not sure what effect if any this type of 'peak duration
reduction' would have on the longevity of the electromagnet?
-----------------------------

TIA for any reply. I've ordered one of these devices, it only cost me $13
and if I can't use it for this I dare say I'll find a use for it some time.

I have smaller airpumps. However most domestic models work by having the
permanent magnet on the end of an arm (which is usually pivoting on an
energy-wasting rubber bush) then the diaphragm/s attached to side of the
arm. These can be mass produced cheaply as tolerances don't need to be as
tight and 'rubber' diaphragm materials don't need to be as good quality as
they're not suspending the armature assembly. However their efficiency
compared with the better ones is much lower (when measured in litres per
second per Watt). More importantly much of the 'wasted' energy goes into
vibration and noise. I like my quiet.

The 'suspended armature' type such as the one I'm currently using are far
more efficient and quiet and I'd hate to go back to a noisy pimp just
because I've decommisioned some tanks.

(Bleeding off air as suggested elsewhere isn't really an option as that's
noisy, wasteful of power and is very hard to balance against the constantly
changing backpressure of a airstones running in biologically active systems.
I know as I've tried other ways in the past. The only way I got it to work
reliably was to bleed off the excess air through an open pipe in a container
of water at a greater depth than the outlet in the fishtanks - a primitive
but sensitive pressure-release system. [You don't want to physically
restrict outlets with simple valves as too much 'hard' restriction distorts
and damages diaphragms and quickly kills the fragile rubber valves.] Its
downsides are noise, having to have a much taller container than needed for
water to contain splash, managing algae and bacterial growth and having to
contsantly adjust depth to compensate for evaporation.)

I guess I could design some sort of fancy feature coloured LED-lit
bubble-wall or semi-closeded similarly-lit clear acrylic cylinder, perhaps
with dyed water (or even oil!) to make use of excess air. However that
wouldn't fit in with my current junk-chic decor.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[~misfit~]

Once upon a time on usenet ~misfit~ wrote:

Once upon a time on usenet Jasen Betts wrote:
On 2016-03-28, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
Once upon a time on usenet Computer Nerd Kev wrote:
block - which isn't available here in NZ and I couldn't find anyone
prepared to ship one to me from Aus, EU, UK.....

https://www.nzpost.co.nz/tools/youshop
"YouShop gives you delivery addresses on the ground in the UK (for
shopping across Europe), USA and China..." not free of course.

Thanks, I'm aware of that (expensive) service. I should have been
clearer - not only couldn't I find anyone to ship the parts to me but
I couldn't actually find a supplier period. That's why the guy in one
of the videos I linked was 3D printing parts for his pump - he
couldn't get parts either and he's in the UK.

Also I found a few places that listed the items I wanted but either said
'out of stock' or, on further questioning or ordering I was then told they
weren't currently available. When asked when they would be nobody could say.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Rheilly Phoull]

On 30/03/2016 8:09 AM, Clocky wrote:

On 27/03/2016 8:03 AM, ~misfit~ wrote:
Hi folks,

I have a large aquarium air pump (Hailea AC-2208) that is quiet and
reliable. However I've reduced the number of fish tanks that I have
and thus
no longer need all of its output. Rather than swap to one of my smaller,
noisier and less relaible pumps I'd like to continue using the Hailea but
reduce its output (reducing its power draw would also be great).

The pump is the vibrator type. A permanent magnet attached to an armature
with diaphragm-type 'compressors' at each end moves from pole to pole
of an
AC electromagnet.

I was wondering if something like this would do the job without
damaging the
pump;
https://www.youtube.com/watch?v=_4PwYm_7HKg

I think this is similar if not the same unit - I can't find the one Clive
reviewed;
http://www.ebay.com/itm/4000W-High-Power-AC-220V-SCR-Electronic-Volt-Regulator-Speed-Controller-Shell-/131413490745?hash=item1e98dabc39:g:abkAAOxyUrZSxoYx


Thanks in advance for any replies.



No not really, it will just make it less efficient but not greatly so
before it just doesn't work.

What it needs is an air bleed to bleed off the excess air you don't want
I should think.

That's what I was thinking. mebbe use the air to drive a small turbine
pump for circulation or power LED lighting.

 

[Clifford Heath]

On 30/03/16 11:42, ~misfit~ wrote:

Once upon a time on usenet Clifford Heath wrote:
On 29/03/16 16:53, ~misfit~ wrote:
Once upon a time on usenet Clifford Heath wrote:
Does the armature have any centering spring around which it
oscillates? If so, then Jason is right and it is resonant at
somewhere near the mains frequency. Changing the frequency will
reduce the efficiency.
Please see my reply to Jason. No spring as such, the centering after
pulses is due to 'rubber' diaphragm suspension. Well I guess they
*are* actually acting as springs in this device but I doubt they'd
have a similar sort of resonant frequency as say a steel spring.

Yup, not much resonance involved then. The "push" energy goes into
one cylinder and the "pull" energy the other; very little into any
energy storage (spring and mass).

Yes, but the resonance is not very high-Q. The goal is to convert
the energy into compressed air, after all. Changing the frequency
if the Q is low will just reduce efficiency, but not
catastrophically.

That's a bit beyond me... Or not if by 'Q' you mean resonant
frequancy of the armature assembly?

Q is a ratio of the amount of energy circulating (stored in the moving
spring & mass in this case) divided by the amount of energy extracted
in each cycle. So if it's putting out 25 watts at 50 cycles per
second, each cycle puts out half a joule. If the spring/mass
oscillation stores (say) 10 joules, the Q is 20 (=10/0.5).

But your pump sounds like it has a Q of less than 1. Not resonant.
Probably operates exactly at mains frequency, and will probably
work at a lower frequency, producing less air volume. Just don't
feed it DC or the magnets will saturate and probably melt wires.
You really need an AC current source, enough to produce the correct
stroke at your desired power output.

Thanks for the reply and explination.
So ideally a variac then - which I'd assumed and which I don't have.

No, ideally, frequency reduction, at the right current.

A variac will work, but will reduce efficiency, because it works by
reducing the stroke length. A certain volume of air in each stroke is
wasted opening and closing valves, and that doesn't become less as the
stroke length reduces, so you lose some efficiency. Probably not enough
to matter much though.

If you used a fixed mains transformer with, say, a 30-0-30V winding,
you could wire the 60v in antiphase from the active to step down to
180v from 240. That might be the cheapest way to reduce output, even
though it's not easily adjustable.

> Do you know if the device that I've ordered will hurt my pump?

It might. I'm not an expert on dimmers, but most don't like inductive
loads. There are leading-edge and trailing-edge dimmers. The trailing
edge dimmer turns off part-way through the half-cycle. With an
inductive load, that will produce massive voltage spikes that will
blow up the dimmer and possibly other things in the vicinity.
The leading-edge dimmers turn on part-way through the half-cycle,
which won't produce a voltage spike.

Neither type is guaranteed to produce balanced AC - you might get
more +ve than -ve or vice versa. That's bad for an iron-cored
inductor because it can easily cause core saturation and high
currents that will melt your windings.

At this point, I'm at the limit of my knowledge. I would trust
Phil A's opinion here. Phil? Tell me what I got wrong please...

I have smaller airpumps. However most domestic models work by having the
permanent magnet on the end of an arm (which is usually pivoting on an
energy-wasting rubber bush)

Wastage depends on the quality of the rubber. Good silicon rubber
wouldn't waste much - but this type is resonant (the rubber is the
spring).

Clifford Heath

 

[Computer Nerd Kev]

Once upon a time on usenet Jasen Betts wrote:
On 2016-03-27, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:

probably reducing the input voltage will do what you want. so a series
dropper of some sort, or a step-down transformer. you could try a fan
speed controller, or to test this out a 100w lamp.

I don't have any of the above.

Actually I may be able to dig out a 60 or 75 watt incandescant light bulb
from the back of the cupboard - I only use LED lamps in the house now,
swapped out the CFLs a while back. What would the effect of wiring an
incandescant bulb in parallel to the pump be? I mentioned I'm new to
electrical theory yes?

That'll drop the input voltage to the pump. You look at the light bulb as
a resistor and use the voltage developed across it (Ohms law) to subtract
from the voltage otherwise applied to the pump. But for heaven's sake wire
it in _series_, not parallel.

The controller you've bought is also a form of voltage control, but as it
works by switching the input waveform rather than droping the voltage over
a resistance, other considerations (inductive spikes, completion of
compressor stroke) arise.

As has been noted, frequency control rather than voltage control may be the
better option. Does anyone know of a cheap, purchasable device that would
achieve this?

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