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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?
It doesn\'t measure airflow, it detects its presence or absence.
The TI application circuit looks pretty simple to me, a low pass filtered charge amp output. The most complex part is positioning and resiliently mounting the piezo film strip.
In article <bffeb1b5-d695-4be5...@googlegroups.com> you wrote:
On Friday, 7 April 2023 at 03:53:57 UTC+2, Bertrand Sindri wrote:
a a <mant...@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
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.
Call it what you can with your little mind, but Dell is smart,
setting PC fans to start at max speed to remove any clogging debris
at first
My, you really are as stupid and have as low an IQ as several group
members are already saying about you.
The \"start at high speed\" mode has *noting* to do with removing
clogging debris. That is nothing more than a false illusion you made
up in your head because you are not intelligent enough to reason out
the actual purpose for the high-speed start.
The high-speed start is because whatever model fan Dell sourced to
build into your machine needs some seconds of \'full power\' applied at
startup in order to get spinning from zero RPM.
Further, high speed air-flow from the fans at 100%, but in the usual
air-flow direction, simply will not dislodge clogging debris. The
faster airflow, in the same direction as always, will only further
embed any \'clogging debris\' into whatever they are stuck upon.
The fans would have to start in reverse airflow direction for a short
time to have any hope of \"dislodging clogging debris\".
You are funny as always
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?
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
On Sun, 9 Apr 2023 11:16:15 +1000, Clifford Heath <no.spam@please.net
wrote:
On 09/04/23 02:00, John Larkin wrote:
On Sat, 08 Apr 2023 07:08:26 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Sat, 8 Apr 2023 21:36:53 +1000, Clifford Heath <no.spam@please.net
wrote:
On 08/04/23 14:04, John Larkin wrote:
On Sat, 8 Apr 2023 13:50:11 +1000, Clifford Heath <no.spam@please.net
wrote:
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.
Read the schematic and explain it to us.
Simple: It\'s amplifying and detecting low-frequency noise from fan
blades and air turbulence (a result of airflow) using PVDS piezo film
sensors. As in, it\'s a fancy kind of low frequency microphone amplifier
with a rumble detector.
They use PVDS in guitar pickups, it\'s very effective and easy to use.
You can even buy it by the A4 sheet and cut it with scissors.
Happy?
No. Spinning fan blades make noise even if air flow is blocked.
More, usually.
It would be possible, maybe even practical, to analize the voltage and
PWM into a fan and the tach output, and compute pressure drop or flow.
That wouldn\'t help my case, where I don\'t own the fans, but it might
be useful elsewhere.
A small fan used in tach-only mode, PWM=0, would be a cheap flow or DP
sensor.
The fan blade noise is probably much higher frequency than the rumble of
vortex shedding airflow around items in the case. These sensors look to
be optimised for this very low frequency rumble. A full schematic would
give you more idea what frequency range they\'re looking at, but I
suspect it\'s in the 2-10Hz range, not the 100\'s Hz that you\'d get from
fan blades.
A cheap electret microphone, located close to fan blades, makes a
gigantic signal.
On 09/04/23 11:30, John Larkin wrote:
On Sun, 9 Apr 2023 11:16:15 +1000, Clifford Heath <no.spam@please.net
wrote:
On 09/04/23 02:00, John Larkin wrote:
On Sat, 08 Apr 2023 07:08:26 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Sat, 8 Apr 2023 21:36:53 +1000, Clifford Heath <no.spam@please.net
wrote:
On 08/04/23 14:04, John Larkin wrote:
On Sat, 8 Apr 2023 13:50:11 +1000, Clifford Heath <no.spam@please.net
wrote:
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.
Read the schematic and explain it to us.
Simple: It\'s amplifying and detecting low-frequency noise from fan
blades and air turbulence (a result of airflow) using PVDS piezo film
sensors. As in, it\'s a fancy kind of low frequency microphone amplifier
with a rumble detector.
They use PVDS in guitar pickups, it\'s very effective and easy to use.
You can even buy it by the A4 sheet and cut it with scissors.
Happy?
No. Spinning fan blades make noise even if air flow is blocked.
More, usually.
It would be possible, maybe even practical, to analize the voltage and
PWM into a fan and the tach output, and compute pressure drop or flow.
That wouldn\'t help my case, where I don\'t own the fans, but it might
be useful elsewhere.
A small fan used in tach-only mode, PWM=0, would be a cheap flow or DP
sensor.
The fan blade noise is probably much higher frequency than the rumble of
vortex shedding airflow around items in the case. These sensors look to
be optimised for this very low frequency rumble. A full schematic would
give you more idea what frequency range they\'re looking at, but I
suspect it\'s in the 2-10Hz range, not the 100\'s Hz that you\'d get from
fan blades.
A cheap electret microphone, located close to fan blades, makes a
gigantic signal.
If you want the rumble but not the fan blades, you want good LF
response. How does the electret go at 5Hz?
On Tue, 11 Apr 2023 14:11:21 +1000, Clifford Heath
no.spam@please.net> wrote:
On 09/04/23 11:30, John Larkin wrote:
On Sun, 9 Apr 2023 11:16:15 +1000, Clifford Heath <no.spam@please.net
wrote:
On 09/04/23 02:00, John Larkin wrote:
On Sat, 08 Apr 2023 07:08:26 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Sat, 8 Apr 2023 21:36:53 +1000, Clifford Heath <no.spam@please.net
wrote:
On 08/04/23 14:04, John Larkin wrote:
On Sat, 8 Apr 2023 13:50:11 +1000, Clifford Heath <no.spam@please.net
wrote:
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.
Read the schematic and explain it to us.
Simple: It\'s amplifying and detecting low-frequency noise from fan
blades and air turbulence (a result of airflow) using PVDS piezo film
sensors. As in, it\'s a fancy kind of low frequency microphone amplifier
with a rumble detector.
They use PVDS in guitar pickups, it\'s very effective and easy to use.
You can even buy it by the A4 sheet and cut it with scissors.
Happy?
No. Spinning fan blades make noise even if air flow is blocked.
More, usually.
It would be possible, maybe even practical, to analize the voltage and
PWM into a fan and the tach output, and compute pressure drop or flow.
That wouldn\'t help my case, where I don\'t own the fans, but it might
be useful elsewhere.
A small fan used in tach-only mode, PWM=0, would be a cheap flow or DP
sensor.
The fan blade noise is probably much higher frequency than the rumble of
vortex shedding airflow around items in the case. These sensors look to
be optimised for this very low frequency rumble. A full schematic would
give you more idea what frequency range they\'re looking at, but I
suspect it\'s in the 2-10Hz range, not the 100\'s Hz that you\'d get from
fan blades.
A cheap electret microphone, located close to fan blades, makes a
gigantic signal.
If you want the rumble but not the fan blades, you want good LF
response. How does the electret go at 5Hz?
I did it in a CAMAC crate. When the fan blade sweeps close to the mic,
it makes a huge sharp spike.
On 11/04/23 14:37, John Larkin wrote:
On Tue, 11 Apr 2023 14:11:21 +1000, Clifford Heath
no.spam@please.net> wrote:
On 09/04/23 11:30, John Larkin wrote:
On Sun, 9 Apr 2023 11:16:15 +1000, Clifford Heath <no.spam@please.net
wrote:
On 09/04/23 02:00, John Larkin wrote:
On Sat, 08 Apr 2023 07:08:26 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Sat, 8 Apr 2023 21:36:53 +1000, Clifford Heath <no.spam@please.net
wrote:
On 08/04/23 14:04, John Larkin wrote:
On Sat, 8 Apr 2023 13:50:11 +1000, Clifford Heath <no.spam@please.net
wrote:
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.
Read the schematic and explain it to us.
Simple: It\'s amplifying and detecting low-frequency noise from fan
blades and air turbulence (a result of airflow) using PVDS piezo film
sensors. As in, it\'s a fancy kind of low frequency microphone amplifier
with a rumble detector.
They use PVDS in guitar pickups, it\'s very effective and easy to use.
You can even buy it by the A4 sheet and cut it with scissors.
Happy?
No. Spinning fan blades make noise even if air flow is blocked.
More, usually.
It would be possible, maybe even practical, to analize the voltage and
PWM into a fan and the tach output, and compute pressure drop or flow.
That wouldn\'t help my case, where I don\'t own the fans, but it might
be useful elsewhere.
A small fan used in tach-only mode, PWM=0, would be a cheap flow or DP
sensor.
The fan blade noise is probably much higher frequency than the rumble of
vortex shedding airflow around items in the case. These sensors look to
be optimised for this very low frequency rumble. A full schematic would
give you more idea what frequency range they\'re looking at, but I
suspect it\'s in the 2-10Hz range, not the 100\'s Hz that you\'d get from
fan blades.
A cheap electret microphone, located close to fan blades, makes a
gigantic signal.
If you want the rumble but not the fan blades, you want good LF
response. How does the electret go at 5Hz?
I did it in a CAMAC crate. When the fan blade sweeps close to the mic,
it makes a huge sharp spike.
I\'m not sure if you\'re being deliberately dense here, because you\'re
clearly smart enough to understand, I must assume you\'re just unwilling.
3000RPM fan, >six blades, that\'s at least 300Hz. If you want to detect
*air flow* instead of fan blades, you need to chuck away anything above
20Hz and look for the real LF stuff that comes from vortex shedding.
That will be what the TI thing does, based on their choice of large PVDS
pads, instead of electrets. This much has been obvious to me from the
beginning, but apparently not to you.
On Tue, 11 Apr 2023 15:40:28 +1000, Clifford Heath <no....@please.net> wrote:
On 11/04/23 14:37, John Larkin wrote:
On Tue, 11 Apr 2023 14:11:21 +1000, Clifford Heath <no....@please.net> wrote:
On 09/04/23 11:30, John Larkin wrote:
On Sun, 9 Apr 2023 11:16:15 +1000, Clifford Heath <no....@please.net> wrote:
On 09/04/23 02:00, John Larkin wrote:
On Sat, 08 Apr 2023 07:08:26 -0700, John Larkin <jla...@highlandSNIPMEtechnology.com> wrote:
On Sat, 8 Apr 2023 21:36:53 +1000, Clifford Heath <no....@please.net> wrote:
On 08/04/23 14:04, John Larkin wrote:
On Sat, 8 Apr 2023 13:50:11 +1000, Clifford Heath <no....@please.net> wrote:
On 08/04/23 10:47, John Larkin wrote:
On Sat, 8 Apr 2023 10:40:16 +1000, Clifford Heath <no....@please.net> wrote:
On 07/04/23 11:49, John Larkin wrote:
On Fri, 7 Apr 2023 11:12:50 +1000, Clifford Heath <no....@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.fred...@gmail.com> wrote:
On Thursday, April 6, 2023 at 12:36:04?AM UTC-4, John Larkin wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3rin9p0k10tnmv16i04f@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <alien@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3rin9p0k10tnmv16i04f@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
On Fri, 07 Apr 2023 12:41:44 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
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?
My inventory program shows
MINCO S262PF
MINCO S247PF12
MURATA TRFA102A
OMEGA F3141
for the ceramic slab 1K thin-film RTD.
The 100 ohm 1206 is
ENERCORP PCS 1.1503.1
VISHAY PTS1206M1B100RP100
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\'d probably have 12 or even 24 volts available in the case I\'m
considering. That would toast a 1K RTD.
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.
It could be very simple, just a couple of timed limit checks. But with
6 GHz of ARM available, we could get fancy.
How fast does loss of airflow need to be detected to avert damage?
I\'d think that one test per minute would be enough. We could probably
manage two. With two fans, nothing will fry soon.
On Fri, 07 Apr 2023 10:14:50 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Fri, 07 Apr 2023 12:41:44 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
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?
My inventory program shows
MINCO S262PF
MINCO S247PF12
MURATA TRFA102A
OMEGA F3141
for the ceramic slab 1K thin-film RTD.
The 100 ohm 1206 is
ENERCORP PCS 1.1503.1
VISHAY PTS1206M1B100RP100
I\'ll look these up.
One thing that strikes me is that some Minco units I looked at had
thin silver wire leads, whereas the TO-92 leads will be kovar, and
maybe the PTFD RTDs as well.
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\'d probably have 12 or even 24 volts available in the case I\'m
considering. That would toast a 1K RTD.
Yes. Probably best to feed the RTD using constant-current sources.
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.
It could be very simple, just a couple of timed limit checks. But with
6 GHz of ARM available, we could get fancy.
I would not depend on any single data point, as this data is likely to
be noisy and impulse-ridden.
Some kind of moving-window median filter is needed at the least, to
prevent random false positives and false negatives.
How fast does loss of airflow need to be detected to avert damage?
I\'d think that one test per minute would be enough. We could probably
manage two. With two fans, nothing will fry soon.
A minute. That ought to suffice.
What if the airflow is blocked by a cleverly-placed random piece of
trash, preventing the fans from doing anything useful?
Probably need to also sense the base temperature of the SMD RTD
regardless of air flow, to trigger shutdown in time.
Joe Gwinn
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <alien@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3rin9p0k10tnmv16i04f@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
On Tue, 11 Apr 2023 07:56:13 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <alien@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3rin9p0k10tnmv16i04f@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
https://www.dropbox.com/sh/p6854tn4p5u1ih8/AABu27KEF4wBVeVYFFxtr8BUa?dl=0
There are new streams running across Donner Pass Road and it\'s an
obstacle course of potholes, and the melt has just begun.
There are trees down all over San Francisco. The wind and rain toppled
a lot of shallow-rooted non-native trees.
https://www.dropbox.com/sh/w95izryfx600edu/AACkEds0Way2x1wfnyNVGxV-a?dl=0
On a sunny day (Tue, 11 Apr 2023 09:47:54 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
oa3b3i97igik4l7l1k7lm74fk7cuelsc4h@4ax.com>:
On Tue, 11 Apr 2023 07:56:13 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <alien@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3rin9p0k10tnmv16i04f@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
https://www.dropbox.com/sh/p6854tn4p5u1ih8/AABu27KEF4wBVeVYFFxtr8BUa?dl=0
Wow! That is very beautiful!
There are new streams running across Donner Pass Road and it\'s an
obstacle course of potholes, and the melt has just begun.
There are trees down all over San Francisco. The wind and rain toppled
a lot of shallow-rooted non-native trees.
https://www.dropbox.com/sh/w95izryfx600edu/AACkEds0Way2x1wfnyNVGxV-a?dl=0
Better watch out when walking there...
Yesterday I was watching one of those survival programs...
Guy climbs all the way up in a coconut tree,
then slipped, and fell while holding on to the tree,
whole body skin red and scratched open, he had to give up.
Must be better ways to get a coconut down...
On a sunny day (Tue, 11 Apr 2023 07:56:13 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
4usa3i5tkls77uijb7oja3uq1mljbqicc1@4ax.com>:
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <alien@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3rin9p0k10tnmv16i04f@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
Yes, storm and rain now here today, but better weather predicted for next week...
I went biking and shopping yesterday, on the way back I had to step off
the bike as I was afraid I would break the transmission chain against the wind
and walked several miles holding the bike.... actually cool..
as a kid I had a whole box of medals for long marches I made.
As to the \'hot wire\' system versus my \'diode system\'.
I do heat the diodes up to above environment with quite bit of current
so it is basically the same idea.
The diodes _have_ to be hotter than the max environment temperature
and using 2 in series put it at about about 1.4 V or so midway the 3.3 V ADC range.
I just use 4 diode pairs for north south west east, but with one
hot diode (or 2 in series) you get the same system as the hot wire thing.
https://panteltje.nl/panteltje/pic/wind_pic_thermal_udp/
You could probably replace the diodes with that sort of wire,
any idea what type of wire is used in that thing you have?
On Wed, 12 Apr 2023 05:44:24 GMT, Jan Panteltje <al...@comet.invalid
wrote:
On a sunny day (Tue, 11 Apr 2023 07:56:13 -0700) it happened John Larkin
jjla...@highlandtechnology.com> wrote in
4usa3i5tkls77uijb...@4ax.com>:
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <al...@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jla...@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3ri...@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
Yes, storm and rain now here today, but better weather predicted for next week...
I went biking and shopping yesterday, on the way back I had to step off
the bike as I was afraid I would break the transmission chain against the wind
and walked several miles holding the bike.... actually cool..
as a kid I had a whole box of medals for long marches I made.
As to the \'hot wire\' system versus my \'diode system\'.
I do heat the diodes up to above environment with quite bit of current
so it is basically the same idea.
The diodes _have_ to be hotter than the max environment temperature
and using 2 in series put it at about about 1.4 V or so midway the 3.3 V ADC range.
I just use 4 diode pairs for north south west east, but with one
hot diode (or 2 in series) you get the same system as the hot wire thing.
https://panteltje.nl/panteltje/pic/wind_pic_thermal_udp/
What is that ethernet thing? I need to add ethernet to a Raspberry Pi
Pico, which doesn\'t have it. The current thinking is to add a WizNet
chip and an RJ45 with PoE magnetics.
You could probably replace the diodes with that sort of wire,
any idea what type of wire is used in that thing you have?
No idea. A hot wire anemometer is appealing but I don\'t have a good,
production-quality, way to get the hot wire.
Suitable wire probably doesn\'t solder well either.
On Wed, 12 Apr 2023 05:44:24 GMT, Jan Panteltje <al...@comet.invalid
wrote:
On a sunny day (Tue, 11 Apr 2023 07:56:13 -0700) it happened John Larkin
jjla...@highlandtechnology.com> wrote in
4usa3i5tkls77uijb...@4ax.com>:
On Mon, 10 Apr 2023 06:12:11 GMT, Jan Panteltje <al...@comet.invalid
wrote:
On a sunny day (Sun, 09 Apr 2023 09:32:44 -0700) it happened John Larkin
jla...@highlandSNIPMEtechnology.com> wrote in
9mp53ipjlshtur3ri...@4ax.com>:
It\'s trivial if it helps up get a multi-million-dollar product right,
or saves even a day of engineering time.
We compared it against a couple of the propeller-type air speed meters
and it agreed nicely.
The other gadget, much cheaper, is to go to Chinatown and buy a bunch
of incense sticks and use the smoke to visualize air flow patterns.
OK, that is the one!
Marihuana?
Weed?
\'High\' speed fan?
You may have a market there!
But I better stay with my 10 dollar propellor thing ;-)
first flowers in the garden are already blooming,
and insects come with it..
Last year I had grapes from the garden, not bad at all!
We had a cold, very wet winter, and then it got warm fast. The plants
are exploding, so much green it hurts our eyes. The roses and the
lemon tree are sagging with fruit and flowers. I expect a good
blackberry year in our canyon.
Lots of trees fell in San Franciso, from the water and wind.
I have some awesome snow pictures too. I\'ll post them soon. It\'s warm
up here in the sierras now and the runoff is already causing troubles.
Yes, storm and rain now here today, but better weather predicted for next week...
I went biking and shopping yesterday, on the way back I had to step off
the bike as I was afraid I would break the transmission chain against the wind
and walked several miles holding the bike.... actually cool..
as a kid I had a whole box of medals for long marches I made.
As to the \'hot wire\' system versus my \'diode system\'.
I do heat the diodes up to above environment with quite bit of current
so it is basically the same idea.
The diodes _have_ to be hotter than the max environment temperature
and using 2 in series put it at about about 1.4 V or so midway the 3.3 V ADC range.
I just use 4 diode pairs for north south west east, but with one
hot diode (or 2 in series) you get the same system as the hot wire thing.
https://panteltje.nl/panteltje/pic/wind_pic_thermal_udp/
What is that ethernet thing? I need to add ethernet to a Raspberry Pi
Pico, which doesn\'t have it. The current thinking is to add a WizNet
chip and an RJ45 with PoE magnetics.