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From: Jim Thompson on 10 May 2010 11:56
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

A re-triggerable one-shot will have an output that stays high until
the minimum pulse rate occurs, then it will be toggling.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

The only thing bipartisan in this country is hypocrisy
From: lektric.dan on 10 May 2010 15:40
On May 10, 10:56 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-
My-Web-Site.com> wrote:
>
> A re-triggerable one-shot will have an output that stays high until
> the minimum pulse rate occurs, then it will be toggling.
>
What if it were capacitivly coupled at the input?
From: Grant on 10 May 2010 17:41
On Mon, 10 May 2010 12:40:19 -0700 (PDT), "lektric.dan(a)gmail.com" <lektric.dan(a)gmail.com> wrote:

>On May 10, 10:56 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-
>My-Web-Site.com> wrote:
>>
>> A re-triggerable one-shot will have an output that stays high until
>> the minimum pulse rate occurs, then it will be toggling.
>>
>What if it were capacitivly coupled at the input?

Output toggles when input rate is less than one-shot period.

Grant.
--
http://bugs.id.au/
From: lektric.dan on 10 May 2010 22:20
On May 10, 4:41 pm, Grant <o...(a)grrr.id.au> wrote:
> On Mon, 10 May 2010 12:40:19 -0700 (PDT), "lektric....(a)gmail.com" <lektric....(a)gmail.com> wrote:
> >On May 10, 10:56 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-
> >My-Web-Site.com> wrote:
>
> >> A re-triggerable one-shot will have an output that stays high until
> >> the minimum pulse rate occurs, then it will be toggling.
>
> >What if it were capacitivly coupled at the input?
>
> Output toggles when input rate is less than one-shot period.  
>
> Grant.
> --http://bugs.id.au/

OK, got it, Misunderstood parent post.
From: whit3rd on 11 May 2010 03:50
On May 9, 12:28 pm, hamilton <hamil...(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...
>
> 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 presume this is a fixed-width pulse with well-conditioned peak and
trough
values? Feed it to an R-C series pair, clamp the other end so it
alternately sources
current and returns to GND. Then integrate (resistor, op amp,
capacitor in negative
feedback) and limit the integrator gain with a resistor across the
feedback
capacitor. It's your basic capacitor current source and ammeter, with
that
clamp diode feeding only the positive half of the current to the
meter.
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