Looking for advise on PC FlowMeter

[GTD]

Hello all, I have a Water Cooled PC, and I would like to make my own
flow sensor. The reason I am wanting to do this, aside from the basic
"I wanna do something I've not done before" , is that every flow
sensor I've seen has been a weenie little 1/4 hose type (My system
uses 1/2" Hose and has quite a bit of flow, and I really don't want to
split and re-route the flow). I can easily build a "paddle wheel"
enclosue, and my idea is to sense the speed of the paddle wheel, and
have the circuitry sent an appropriate pulse signal to one of the
motherboard's fan headers, where it can then be read by MBM or
whatever software I use. This unit will not have any exposed shaft, so
I am basically limited to a magnetic pickup arrangment (I will embed
the magnets in the paddlewheel if need be), or a photocell type (with
the paddlewheel breaking or reflecting the beam). If anyone has an
idea of where to find schematics for a project such as this, I would
appreciate it. I must say that I've done a bit of electronics, but it
has been quite a few years. Thanks.

----------------------------------------------------------------------

You should start drinking prune juice and KY jelly cocktails right now,
that will make things a lot smoother.
-Felatio Love

 

[GTD]

Nice but you will have to have a way to multiply the paddle wheel pulses
into the KHz range. Most system fans want about 3500 RPM to prevent
a 'fan to slow' alarm. I am assuming that one revolution of the fan results
in one pulse on the tach, you'll have to test that theory. Perhaps a phase
locked loop (PLL) with a divider in the feedback path will do. Look at
the spec sheet for a 4046 here:
http://www.semiconductors.philips.com/acrobat_download/datasheets/HEF4046B_CNV_3.pdf

Thanks for the ideas, much appreciated. I could and probably will set
it up with 3 or 4 magnets, so it'l be that many pulses per rev. It
will have to have at least two just to keep the paddle balanced. The
software I'll be using is very flexible, and the fan speed alarm do
not have to be used.

Don Lancaster has a section in his 'CMOS Cookbook' regarding this device.
Don's web site is www.tinaja.com
I'll check it out, thanks.

I'm guessing that there is a pump motor in this cooling system, what about
stealing a tach signal from there?
This won't help me if a line gets plugged, the pump goes ntts, or

something stupid like that. Also, I'm interested in seeing just a
simple drop in flow rate as opposed to waiting for a complete stoppage
if something bites it.

How about a temperature to frequency circuit?
I'd rather not wait for the temp to go up, by then it may be too late.

----------------------------------------------------------------------

You should start drinking prune juice and KY jelly cocktails right now,
that will make things a lot smoother.
-Felatio Love

 

[Bob Masta]

On Tue, 15 Mar 2005 18:47:46 -0900, GTD <duh@stoopid.net> wrote:

Hello all, I have a Water Cooled PC, and I would like to make my own
flow sensor.
snip

Another approach would be to skip the moving parts
completely, and just hang a transistor or diode junction
in the flow path.
Apply a small current to get it to self heat, and measure
the voltage drop across the junction. This is linearly
proportional to temperature, so you can thus determine
how much cooling is taking place. There are all sorts
of schemes based around this concept, often involving
a second such sensor in a bridge arrangement.
It's commonly used for airspeed measurement.
You may want to look up "hot wire anemometer",
since this was originally done with resistance wire
instead of junctions.

Best regards,



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[GTD]

You could recover the hall effect sensor from an old fan and use it directly
as there would be no contact bounce. Many newer fans contain an IC that
includes the coil drive transistors and the 4 or so passives that the old
style
needed. I have yet to investigate these for potential reuse.
I've thought of that, and have been going through all my crap looking

for a 3-wird fan, no luck so far, but I'm sure I'll find one.

If the cooling system plugs up and the heat rises, the motherboards should
already take care of this situation by slowing or shutting down besides, the
temperature rise is a simple scaling operation ... how much temp to tolerate
before it is a problem.
This is an AMD based system, sop there is no thermal throttling. The

fact that the system is overclocked/overvolted means the temp will
rise fairly quickly, but I'm sure the onboardprotection systems will
work well enough. Basically, my need for a software-monitorable flow
sensor is more of a want than a need. It is also to help me test
different pumps, waterblocks, ect.

For the plumbing to stop up, assuming the pump continues to run, you could
use a change in fluid level within a bottle to detect this situation.

----------------------------------------------------------------------

You should start drinking prune juice and KY jelly cocktails right now,
that will make things a lot smoother.
-Felatio Love

 

[Lord Garth]

"GTD" <duh@stoopid.net> wrote in message
news:7j7k31d88ma2tg2p7jb3s85s8j2a1cbuig@4ax.com...

You could recover the hall effect sensor from an old fan and use it
directly
as there would be no contact bounce. Many newer fans contain an IC that
includes the coil drive transistors and the 4 or so passives that the old
style
needed. I have yet to investigate these for potential reuse.
I've thought of that, and have been going through all my crap looking
for a 3-wird fan, no luck so far, but I'm sure I'll find one.

These sensors or in every fan as their purpose is to replace the mechanical
commutator.
A typical third wire tach fan simply outputs one of the coil pulses. That's
why you should
not pay a big premium for this 'cheap to include' feature.

I have one fan that has a stall sensor built in. I suppose the output is
constantly reset by a
moving fan. In any case, you get a signal if the fan stops.

 

[Lord Garth]

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.03.17.03.02.06.519512@example.net...

On Tue, 15 Mar 2005 18:47:46 -0900, GTD wrote:


You could make it dead simple. Mount a reed switch where it's actuated
by your paddle wheel magnets. Ground one side of the reed switch, connect
the other side of the switch to your input pin, with 4K7 pullup to +5V.
Maybe a 1 nf cap across the switch, just because you can. (try it with
and without a cap, and see if it affects your debounce code).

Debounce it in software - you've got all day to do that, practically.

You could recover the hall effect sensor from an old fan and use it directly
as there would be no contact bounce. Many newer fans contain an IC that
includes the coil drive transistors and the 4 or so passives that the old
style
needed. I have yet to investigate these for potential reuse.

If the cooling system plugs up and the heat rises, the motherboards should
already take care of this situation by slowing or shutting down besides, the
temperature rise is a simple scaling operation ... how much temp to tolerate
before it is a problem.

For the plumbing to stop up, assuming the pump continues to run, you could
use a change in fluid level within a bottle to detect this situation.

 

[Lord Garth]

"GTD" <duh@stoopid.net> wrote in message
news2bf31po3jg6jrm998njajcqfsju93rr82@4ax.com...

Hello all, I have a Water Cooled PC, and I would like to make my own
flow sensor. The reason I am wanting to do this, aside from the basic
"I wanna do something I've not done before" , is that every flow
sensor I've seen has been a weenie little 1/4 hose type (My system
uses 1/2" Hose and has quite a bit of flow, and I really don't want to
split and re-route the flow). I can easily build a "paddle wheel"
enclosue, and my idea is to sense the speed of the paddle wheel, and
have the circuitry sent an appropriate pulse signal to one of the
motherboard's fan headers, where it can then be read by MBM or
whatever software I use. This unit will not have any exposed shaft, so
I am basically limited to a magnetic pickup arrangment (I will embed
the magnets in the paddlewheel if need be), or a photocell type (with
the paddlewheel breaking or reflecting the beam). If anyone has an
idea of where to find schematics for a project such as this, I would
appreciate it. I must say that I've done a bit of electronics, but it
has been quite a few years. Thanks.

Nice but you will have to have a way to multiply the paddle wheel pulses
into the KHz range. Most system fans want about 3500 RPM to prevent
a 'fan to slow' alarm. I am assuming that one revolution of the fan results
in one pulse on the tach, you'll have to test that theory. Perhaps a phase
locked loop (PLL) with a divider in the feedback path will do. Look at
the spec sheet for a 4046 here:
http://www.semiconductors.philips.com/acrobat_download/datasheets/HEF4046B_CNV_3.pdf

Don Lancaster has a section in his 'CMOS Cookbook' regarding this device.
Don's web site is www.tinaja.com

I'm guessing that there is a pump motor in this cooling system, what about
stealing a tach signal from there?

How about a temperature to frequency circuit?

 

[Rich Grise]

On Tue, 15 Mar 2005 18:47:46 -0900, GTD wrote:

Hello all, I have a Water Cooled PC, and I would like to make my own
flow sensor. The reason I am wanting to do this, aside from the basic
"I wanna do something I've not done before" , is that every flow
sensor I've seen has been a weenie little 1/4 hose type (My system
uses 1/2" Hose and has quite a bit of flow, and I really don't want to
split and re-route the flow). I can easily build a "paddle wheel"
enclosue, and my idea is to sense the speed of the paddle wheel, and
have the circuitry sent an appropriate pulse signal to one of the
motherboard's fan headers, where it can then be read by MBM or
whatever software I use. This unit will not have any exposed shaft, so
I am basically limited to a magnetic pickup arrangment (I will embed
the magnets in the paddlewheel if need be), or a photocell type (with
the paddlewheel breaking or reflecting the beam). If anyone has an
idea of where to find schematics for a project such as this, I would
appreciate it. I must say that I've done a bit of electronics, but it
has been quite a few years. Thanks.

You could make it dead simple. Mount a reed switch where it's actuated
by your paddle wheel magnets. Ground one side of the reed switch, connect
the other side of the switch to your input pin, with 4K7 pullup to +5V.
Maybe a 1 nf cap across the switch, just because you can. (try it with
and without a cap, and see if it affects your debounce code).

Debounce it in software - you've got all day to do that, practically.

Have Fun!
Rich