Flow Sensors revistied
in [Design]
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From: hamilton on 9 May 2010 15:28 I have been asked to build a digital to analog circuit. The flow sensor: http://www.gemssensors.com/uploadedFiles/Literature/Spec_Sheets/FT210_1124.pdf has a digital pulse output proportional to the flow. I would like to create an analog detector, so when it has reached a minimum flow rate, a logic level is triggered. I am a firmware guy and know how to do this with a PYFMC[1]. I would like to get some suggestions on how to do this in analog. thanks hamilton [1] Pick Your Favorite Micro Controller
From: John Larkin on 9 May 2010 15:37 On Sun, 09 May 2010 13:28:51 -0600, hamilton <hamilton(a)nothere.com> wrote: > >I have been asked to build a digital to analog circuit. > >The flow sensor: >http://www.gemssensors.com/uploadedFiles/Literature/Spec_Sheets/FT210_1124.pdf > >has a digital pulse output proportional to the flow. > >I would like to create an analog detector, so when it has reached a >minimum flow rate, a logic level is triggered. > >I am a firmware guy and know how to do this with a PYFMC[1]. > >I would like to get some suggestions on how to do this in analog. > > >thanks > >hamilton > >[1] Pick Your Favorite Micro Controller You could use my Double-Tach circuit followed by an analog comparator. ftp://jjlarkin.lmi.net/DoubleTach.jpg Or maybe just a couple of cascaded retriggerable one-shots, if all you need is the single underspeed indication. That's simple. Nice looking sensor. What does it cost? John
From: Tauno Voipio on 9 May 2010 15:40 hamilton wrote: > > I have been asked to build a digital to analog circuit. > > The flow sensor: > http://www.gemssensors.com/uploadedFiles/Literature/Spec_Sheets/FT210_1124.pdf > > > has a digital pulse output proportional to the flow. > > I would like to create an analog detector, so when it has reached a > minimum flow rate, a logic level is triggered. > > I am a firmware guy and know how to do this with a PYFMC[1]. > > I would like to get some suggestions on how to do this in analog. > > > thanks > > hamilton > > [1] Pick Your Favorite Micro Controller The solution depends quite much on the required accuracy of the detection. An analog approach would be a monostable for constant-width pulses, smoothing the pulse train to a DC level, and finally comparing it against a threshold voltage. The achievable precision and stability are modest. A digital approach would include a monostable set for the threshold interval, and a latch to capture the previous monostable output at next triggering instant. PYFMC controlled by a crystal may be the most cost-effective solution for good accuracy. -- Tauno Voipio tauno voipio (at) iki fi
From: Jan Panteltje on 9 May 2010 16:49 On a sunny day (Sun, 09 May 2010 13:28:51 -0600) it happened hamilton <hamilton(a)nothere.com> wrote in <hs72dh$otf$1(a)news.eternal-september.org>: > >I have been asked to build a digital to analog circuit. > >The flow sensor: >http://www.gemssensors.com/uploadedFiles/Literature/Spec_Sheets/FT210_1124.pdf > >has a digital pulse output proportional to the flow. > >I would like to create an analog detector, so when it has reached a >minimum flow rate, a logic level is triggered. > >I am a firmware guy and know how to do this with a PYFMC[1]. > >I would like to get some suggestions on how to do this in analog. If it is just a pulse, one shot -> low pass -> analog comparator. The one shot makes a fixed pulse width, the more pusles the higher the voltage after the lowpass, the comparator flips on a specific voltage level, and then triggers the lever that releases the apple that falls on the detonator that triggers the nuke. > >thanks YAW >hamilton > >[1] Pick Your Favorite Micro Controller >
From: hamilton on 9 May 2010 17:27
On 5/9/2010 1:37 PM, John Larkin wrote: > On Sun, 09 May 2010 13:28:51 -0600, hamilton<hamilton(a)nothere.com> > wrote: > >> >> I have been asked to build a digital to analog circuit. >> >> The flow sensor: >> http://www.gemssensors.com/uploadedFiles/Literature/Spec_Sheets/FT210_1124.pdf >> >> has a digital pulse output proportional to the flow. >> >> I would like to create an analog detector, so when it has reached a >> minimum flow rate, a logic level is triggered. >> >> I am a firmware guy and know how to do this with a PYFMC[1]. >> >> I would like to get some suggestions on how to do this in analog. >> >> >> thanks >> >> hamilton >> >> [1] Pick Your Favorite Micro Controller > > > You could use my Double-Tach circuit followed by an analog comparator. > > ftp://jjlarkin.lmi.net/DoubleTach.jpg > > > Or maybe just a couple of cascaded retriggerable one-shots, if all you > need is the single underspeed indication. That's simple. Thanks, Yes, underspeed is the goal. Just an output logic level going to another micro that controls the rest of the system. > > > Nice looking sensor. What does it cost? AAck $100 each !!! The boss thinks he need the accuracy. With the other comments, I will use a PYFMC [2] and just count pulses. The data sheet states the range is 37 to 917 Hz. (.1 to 2.5 LPM). hamilton [2] This time I'll use an AVR. |