[Lab] The Big Plan - Chris B

Fri Mar 15 10:01:48 EDT 2013

Just thinking that 83cm of H2O is about 1 psi and maybe too high for measuring the pressure.
But you might be able to repurpose an old audio speaker and with a suitable low pass filter (<1Hz)
make it work.

On 2013-03-15, at 9:09 AM, Roman Gargulak <roman at cncwings.com> wrote:

> At first, I also thought about a microphone solution with simple passband filter that would be tuned to the ventilator sound, but using pressure sensor makes much more sense IMAO.
> 
> Someone already posted link to the Digikey website with suitable sensor (credit goes to that gentleman):
> <http://www.digikey.com/product-detail/en/MPVZ5010GW7U/MPVZ5010GW7U-ND/1168379>
> 
> It has pressure range from 0 to 83cm H2O and proportional analog voltage output from 0V to 4.75V, ideal for this application.
> That can be tied directly to a comparator circuit to produce a voltage depended PWM. Simple circuit with few op amps, some transistors, few resistors and caps.
> Done, no programming required.
> 
> As pressure rises duty cycle increases, pressure collapses, duty cycle decreases, no pressure, 0 duty cycle.
> Or the whole process can be inverted as needed.
> 
> Sensor is about $15, all the other components would be in the same ball park, $15-$25.
> The most expensive part would be the LED light. I stopped at the Battery Expert here in Orleans the other day and they have nice 12V emergency LED lights that may be good for this project.
> Not cheap though, $75 for this fixture <http://www.batteriesexpert.com/media//pdfs/3033010060_2.pdf>
> 
> just my $0.02
> 
> Roman
> 
> 
> 
> 
> On 3/15/2013 8:41 AM, Michael Sepa wrote:
>> Chris,
>> 
>> The clarification of the project really helps out.  I looked up the manual for the Puritan Bennet LP10 (http://www.meql.com/Manuals/Puritan-Bennett-LP6-Plus-and-10-Ops-Manual.pdf) in the hope that there would be a simple electronic monitor connector on the back that you could hook into, but no such luck.  There are pressure alarms that can be set and a remote alarm connection on the back of the machine, but you'll get audible alarms off the machine at the same time.  Not what you intend.
>> 
>> One approach would be to do the following:
>> 
>> 1. Lights start off, no ventilator pressure
>> 2. Ventilator turns on, a microphone beside the patient air tube senses flow
>> 3. Arduino detects change from microphone
>> 4. Arudino uses pulse width modulation[2] to brighten an LED array from off to full on in 1.5s, and holds
>> 5. Ventilator turns off
>> 6. Microphone detects stop of flow from patient air tube
>> 7. Arduino uses pulse width modulation to dim an LED array from current level to off in 1.5s and holds
>> 
>> [1] pulse width modulation is just a fancy way to say turn on/off the LED array fast enough to control brightness.  This is built into the Arduino system, so it's very easy.
>> 
>> Connecting to and dimming an LED array with an Arduino is well understood.  No issues there.
>> 
>> The microphone will require an amp chip to get it producing a signal the Arduino can easily read.  If we can find a pre-made microphone and amp, then it will be all so much easier.
>> 
>> The programming of the system would be straight forward.  Certainly less than a day of effort.
>> 
>> The system would work well if the room was reasonably quiet.  If there was other noise it might trigger the microphone causing premature light adjustment.  A better approach would be to use a pressure sensor.  I checked ebay and see several pressure sensors available, all use I2C interfaces.  That would take a bit more programming effort, but certainly less than a day or two.
>> 
>> If you go with a pressure sensor, we'd need to makes sure the sensor has the right range to sense the ventilator pressure.  That I couldn't get from the quick ebay search because they don't usually publish specs with sale items.  I'm confident  we could find an appropriate one on ebay, spark fun, or somewhere else.
>> 
>> As for your budget, I'd think you should have no issues buying all the tech plus paying someone a small honorarium for helping you program it all.
>> 
>> My big question would be what's your schedule?
>> 
>> -Michael Sepa
>> 
>> 
>> Date: Thu, 14 Mar 2013 17:49:08 -0400
>> From: The Big Plan - Chris B <tbp at ghostwise.com>
>> To: lab at artengine.ca
>> Subject: Re: [Lab] Controlling Light with Sound
>> Message-ID: <F3148EB9-8831-464E-92AA-2144AB15E72B at ghostwise.com>
>> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>> 
>> Hi everyone,
>> Thanks for the awesome replies so far. I think I should clarify my  
>> intentions:
>> My plan is to suspend a loose canvas that is approximately 7 by 11  
>> feet on an angle from the ceiling.
>> I would like to put lighting behind it (I don't know what lighting to  
>> use or whether it
>> should be a set of lights). The rest of the room will be dark.
>> A ventilator (Puritan Bennett LP10) will be on the floor. Every breath  
>> of the ventilator
>> should cause the lights to turn on in a gradual way and then dim dark  
>> as the breath
>> ends. Each breath should take about 1.2-1.5 seconds.
>> I like the idea of an Arduino or Raspberry Pi controlling the lighting.
>> It sounds like I will also need a mic by the ventilator.
>> Finally, I have zero programming experience or overall technical  
>> experience to do this. I'm the artist
>> with a vision. I would appreciate assistance from anyone interested in  
>> this project.
>> It would be great if it could be done on a $250-500 budget.
>> Thanks in advance,
>> Chris
>> On 14-Mar-13, at 4:11 PM, The Big Plan - Chris B wrote:
>>> 
>>> Hi!
>>> 
>>> Looking for some advice for an art installation. I'd like to have a  
>>> light or set of lights respond to an auditory
>>> input. I'd like the lights to turn on in time with the sound of a  
>>> ventilator (a medical one). So when the ventilator is
>>> not doing a breath, the lights would be off, but then when the  
>>> ventilator starts doing a breath they would
>>> turn on for the duration of the breath. I'd like the lights to light  
>>> up and dim gradually, not just on an off.
>>> 
>>> What's a simple or best way to do this?
>>> 
>>> Thanks!
>>> 
>>> Chris
>>> 
>>> _______________________________________________
>>> Lab mailing list
>>> Lab at artengine.ca
>>> http://artengine.ca/mailman/listinfo/lab
>> 
>> 
>> 
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