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On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
On 07/04/23 09:18, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
Shift in time-of-flight. The projects I\'ve seen use four in a square,
and measure TOF across the diagonals. Needs temperature and humidity
compensation to be accurate.
I am living on an old Dell PC and when I power it on, it starts with
fans at higher speed to remove debris collected from the air
a a <manta103g@gmail.com> wrote:
I am living on an old Dell PC and when I power it on, it starts with
fans at higher speed to remove debris collected from the air
Incorrect as usual.
The reason the fans start at high speed is that the PWM controlled fans
that Dell installed do not startup at anything other than a high duty
cycle PWM waveform. Once spinning, they can be throttled down to their
usual RPM sufficient to maintain cooling. But to initially get started
spinning, they require that high speed jolt.
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
On Fri, 07 Apr 2023 01:53:49 GMT, Bertrand Sindri
bertrand.sindri@yahoo.com> wrote:
a a <manta103g@gmail.com> wrote:
I am living on an old Dell PC and when I power it on, it starts with
fans at higher speed to remove debris collected from the air
Incorrect as usual.
The reason the fans start at high speed is that the PWM controlled fans
that Dell installed do not startup at anything other than a high duty
cycle PWM waveform. Once spinning, they can be throttled down to their
usual RPM sufficient to maintain cooling. But to initially get started
spinning, they require that high speed jolt.
The PWM fans the we have used will start spinning at low PWM duty
cycle. We start them at powerup at some minimum quiet speed, and then
slew up gently to max if measured temperature is high. That avoids
rude noises.
On 4/7/2023 7:26, John Larkin wrote:
On Fri, 07 Apr 2023 01:53:49 GMT, Bertrand Sindri
bertrand.sindri@yahoo.com> wrote:
a a <manta103g@gmail.com> wrote:
I am living on an old Dell PC and when I power it on, it starts with
fans at higher speed to remove debris collected from the air
Incorrect as usual.
The reason the fans start at high speed is that the PWM controlled fans
that Dell installed do not startup at anything other than a high duty
cycle PWM waveform. Once spinning, they can be throttled down to their
usual RPM sufficient to maintain cooling. But to initially get started
spinning, they require that high speed jolt.
The PWM fans the we have used will start spinning at low PWM duty
cycle. We start them at powerup at some minimum quiet speed, and then
slew up gently to max if measured temperature is high. That avoids
rude noises.
May be they make them smart enough to do just a few periods of 100%,
see them (can they?) started without going to high speed and then
just do the pwm you have set?
I am wondering because I have not had a PWM fan in my hands (did not
know such existed, really). Some 30 years ago I did PWM on a normal
12V fan on the first nukeman (the second,
http://tgi-sci.com/tgi/pntb.htm copied that) and I had to go
for a period of something like a whole second IIRC, the thing would
not move otherwise. And I did have to start it initially at full
power so it would start; and yes, the very low PWM frequency
was audible... if this can be called pwm, it was more an on/off
thing.
I\'d have to check those PWM fans, lately (on the tld readers) I
just did on/off, long time on/off that, is some 1C hysteresis etc.
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
On Thursday, April 6, 2023 at 7:18:50?PM UTC-4, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
I thought it was a resonance effect, it might be, but others are using it to pick up periodic turbulence in airstream caused by fan blade rotation.
See Fan Flow Sensor page 48
https://www.sparkfun.com/datasheets/Sensors/Flex/MSI-techman.pdf
Then TE has an extensive catalog of sensors, the DT1 film sensors, page 24.
https://www.te.com/content/dam/te-com/documents/sensors/global/te-sensor-solutions-catalog.pdf
On Fri, 7 Apr 2023 07:42:07 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 7:18:50?PM UTC-4, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
I thought it was a resonance effect, it might be, but others are using it to pick up periodic turbulence in airstream caused by fan blade rotation.
Probably, but air flow could be blocked and fan blades would still
flap the sensor. May as well just use the free tach.
See Fan Flow Sensor page 48
https://www.sparkfun.com/datasheets/Sensors/Flex/MSI-techman.pdf
Then TE has an extensive catalog of sensors, the DT1 film sensors, page 24.
https://www.te.com/content/dam/te-com/documents/sensors/global/te-sensor-solutions-catalog.pdf
On Thu, 06 Apr 2023 13:51:54 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Thu, 06 Apr 2023 09:39:19 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 06 Apr 2023 12:00:15 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Wed, 05 Apr 2023 21:35:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
One can get 1000-ohm platinum RTDs for small dollars:
.<https://www.newark.com/te-connectivity-sensors/nb-ptco-012/rtd-sensor-thin-film-platinum/dp/03AC1640
If the issue is just to tell if there is a lot of airflow, the
temperature delta does not need to be large, so a simple bridge with
AC source and synchronous detector should work.
Cheaper still are RTDs made of nickel, versus platinum. Nickel is OK
if the temperature in still air isn\'t too high.
Joe Gwinn
We use leaded ceramic slab and 1206 platinum RTDs, and a cute SOT23
nickel RTD, but they would be down flat on the PC board. I think it
would be better to get the sensor up in the air stream, so the
preferred gadget might be a TO92 transistor.
A 2N4402 costs us 7 cents. An RTD wouldn\'t break the bank, but simple
and cheap are games we play.
Metallic RTDs are quite stable, and the PTFD form (in the datasheet
above) can stick up 10 mm, which is about the same as a TO-92. One
can compare a SMD version with a nearby PTFD version, canceling local
ambient temp variation.
That\'s a good price. We have an essentially identical Minco part in
stock that costs $4. But it would be flimsy to mount on a board,
sticking up into the air flow.
And it needs to self-heat to measure
flow.
I guess I could do my sequenced heat and cool time constant
measurement on it.
But the RTDs are ~10 times more expensive than 7 cents. Don\'t know
how much difference that makes in this application.
Not a big deal, but may as well save money if it doesn\'t take a huge
hassle.
On Thu, 06 Apr 2023 16:12:31 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 06 Apr 2023 13:51:54 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Thu, 06 Apr 2023 09:39:19 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 06 Apr 2023 12:00:15 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Wed, 05 Apr 2023 21:35:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
One can get 1000-ohm platinum RTDs for small dollars:
.<https://www.newark.com/te-connectivity-sensors/nb-ptco-012/rtd-sensor-thin-film-platinum/dp/03AC1640
If the issue is just to tell if there is a lot of airflow, the
temperature delta does not need to be large, so a simple bridge with
AC source and synchronous detector should work.
Cheaper still are RTDs made of nickel, versus platinum. Nickel is OK
if the temperature in still air isn\'t too high.
Joe Gwinn
We use leaded ceramic slab and 1206 platinum RTDs, and a cute SOT23
nickel RTD, but they would be down flat on the PC board. I think it
would be better to get the sensor up in the air stream, so the
preferred gadget might be a TO92 transistor.
A 2N4402 costs us 7 cents. An RTD wouldn\'t break the bank, but simple
and cheap are games we play.
Metallic RTDs are quite stable, and the PTFD form (in the datasheet
above) can stick up 10 mm, which is about the same as a TO-92. One
can compare a SMD version with a nearby PTFD version, canceling local
ambient temp variation.
That\'s a good price. We have an essentially identical Minco part in
stock that costs $4. But it would be flimsy to mount on a board,
sticking up into the air flow.
I would guess that a TO-92 and a PTFD RTD are equally fragile in
practice. Don\'t know about the Minco. Part number?
And it needs to self-heat to measure
flow.
Isn\'t that true in general?
A 100-ohm RTD will be easier to heat from 5 volts than the 1000-ohm
RTD, but one tenth as sensitive to temperature change, so there is a
tradeoff to be made.
I guess I could do my sequenced heat and cool time constant
measurement on it.
Sort of like a ring-down measurement - fit the log of the offset
versus time to a line, which can be done pretty fast - fever
thermometers do this and the algorithm is simple. So it could work.
How fast does loss of airflow need to be detected to avert damage?
But the RTDs are ~10 times more expensive than 7 cents. Don\'t know
how much difference that makes in this application.
Not a big deal, but may as well save money if it doesn\'t take a huge
hassle.
Yeah.
Joe Gwinn
On Friday, April 7, 2023 at 11:16:16?AM UTC-4, John Larkin wrote:
On Fri, 7 Apr 2023 07:42:07 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 7:18:50?PM UTC-4, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
I thought it was a resonance effect, it might be, but others are using it to pick up periodic turbulence in airstream caused by fan blade rotation.
Probably, but air flow could be blocked and fan blades would still
flap the sensor. May as well just use the free tach.
That\'s a point. What do you plan on your product doing when it loses airflow?
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? [...]
On 4/6/2023 12:35 AM, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? [...]
Am I missing something: you want to check airflow so that you can
prevent the board from overheating, right?
If so, why don\'t you just
measure the temperature directly? There must be spots on the board that
would be the first to overheat and give the alarm.
On Fri, 7 Apr 2023 11:12:50 +1000, Clifford Heath <no.spam@please.net
wrote:
On 07/04/23 09:18, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
Shift in time-of-flight. The projects I\'ve seen use four in a square,
and measure TOF across the diagonals. Needs temperature and humidity
compensation to be accurate.
Both of the piezos in the TI diagram seem to be receivers. And the
signal path includes rectifiers and \"smoothing.\" That doesn\'t look
like TOF.
On 07/04/23 11:49, John Larkin wrote:
On Fri, 7 Apr 2023 11:12:50 +1000, Clifford Heath <no.spam@please.net
wrote:
On 07/04/23 09:18, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
Shift in time-of-flight. The projects I\'ve seen use four in a square,
and measure TOF across the diagonals. Needs temperature and humidity
compensation to be accurate.
Both of the piezos in the TI diagram seem to be receivers. And the
signal path includes rectifiers and \"smoothing.\" That doesn\'t look
like TOF.
Haven\'t looked at the schematic or app note,
On Sat, 8 Apr 2023 10:40:16 +1000, Clifford Heath <no.spam@please.net
wrote:
On 07/04/23 11:49, John Larkin wrote:
On Fri, 7 Apr 2023 11:12:50 +1000, Clifford Heath <no.spam@please.net
wrote:
On 07/04/23 09:18, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
Shift in time-of-flight. The projects I\'ve seen use four in a square,
and measure TOF across the diagonals. Needs temperature and humidity
compensation to be accurate.
Both of the piezos in the TI diagram seem to be receivers. And the
signal path includes rectifiers and \"smoothing.\" That doesn\'t look
like TOF.
Haven\'t looked at the schematic or app note,
You can\'t say much about them if you don\'t.
On 08/04/23 10:47, John Larkin wrote:
On Sat, 8 Apr 2023 10:40:16 +1000, Clifford Heath <no.spam@please.net
wrote:
On 07/04/23 11:49, John Larkin wrote:
On Fri, 7 Apr 2023 11:12:50 +1000, Clifford Heath <no.spam@please.net
wrote:
On 07/04/23 09:18, John Larkin wrote:
On Thu, 6 Apr 2023 14:41:35 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
Given a PC board in a crate, like PCIe or PXI or VME or something,
what would be a good way to check air flow across the board, to verify
that the box fans and filters are OK? Assume this board can\'t access
the fan tachs or anything like that.
I was thinking that I might stick a small thinfilm RTD in the air
stream and measure its temperature at two different voltages, to
estimate its self-heating, which would vary with air flow.
The classic broken light bulb hot-wire anemometer is a nuisance.
Carbon comp resistor?
This can\'t be a new problem. Any other suggestions?
A piezoelectric air flow sensor is more in line with detecting the presence/ absence of air flow. The signal conditioning then becomes simplified. TI has this crazily named thing:
https://www.ti.com/lit/ug/tidu372/tidu372.pdf
Dunno if that leaf shaped sensor is supposed to flutter or the flexure changes its resonance. Seems I\'ve seen those for sale separately for ~ $10.
System Description
This Piezoelectric Airflow Sensor is intended for
use in systems that require fan airflow detection.
This can include server intake/exhaust airflow
detection, as well as desktop computer airflow.
The Piezoelectric Airflow Sensor design is a
simple, low cost solution which would help
designers who are looking for a means to detect
the presence or absence of fan airflow in existing
systems.
That\'s insanely complex. Not hardly \"simple, low cost.\"
Do you have any idea how the piezo sensors measure air flow?
Shift in time-of-flight. The projects I\'ve seen use four in a square,
and measure TOF across the diagonals. Needs temperature and humidity
compensation to be accurate.
Both of the piezos in the TI diagram seem to be receivers. And the
signal path includes rectifiers and \"smoothing.\" That doesn\'t look
like TOF.
Haven\'t looked at the schematic or app note,
You can\'t say much about them if you don\'t.
Don\'t be a dill. Ultrasonic air-speed sensors are as old as the hills.