We still have an order of magnitude of cost problems here:  $12 sensor vs. $300 decent meter.  Of course, more than a sensor is required, but really not much.  I have it hooked to an Arduino with an added on SD card datalogger module.  Even in single piece quantity <$60, and for this sensor app I might not need the datalogger, saving $20.

This discussion has been great at getting me out of my mental block.

Besides other ideas, I just concluded I should try waving a single thin hair in the sensor.  If I wave it around a lot and average the result, maybe I can get something repeatable.  Actual implementation might be a thin tungsten rod driven eccentrically by a cheap phone vibrator motor.  

I don't believe there is enough profit in this to attract a commercial developer.  If people don't donate the time to develop it, I think it's a no-go.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
Sent: Friday, August 30, 2013 2:00 AM
To: [log in to unmask]
Subject: Re: [TN] Blowing Smoke

Quite different solution: ask HANNA if they can't make a cheap turbdity meter. They should, if you tell them the lots of meters needed .

http://www.amazon.com/Hanna-Instruments-Turbidity-Technology-Compliant/dp/B002NX0WJG


On 29 August 2013 15:59, Pat Goodyear <[log in to unmask]> wrote:

> Optical detector rings a bell, 20 years ago we had a Forward Scatter
> Meter, we used it at the plant to measure the density of the fog.    Had
> nothing to do with humidity but it was for visibility.    If I remember
> correctly it had a shielded IR light source on one arm facing a 
> shielded photo detector array on an opposite arm about 2 meters separating them. I
> think they use a similar device at airports.    Maybe a device of that type
> may work on a smaller scale.   Zero point would be no interference, high
> level would be the point at which the air quality is uninhabitable, 
> and possibly a logarithmic scale in between.
>
> Pat
>
>
> On Thu, Aug 29, 2013 at 11:04 AM, Wayne Thayer wrote:
>
>  That's different thinking!
>>
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
>> Sent: Thursday, August 29, 2013 1:59 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blowing Smoke
>>
>> If this is an optical detector, why do you need actual smoke? Put a 
>> piece of tinted plexiglass in the detector as a calibration standard 
>> in the field. You can figure out what density of particles it is 
>> equivalent to in a lab with a particle counter.
>>
>> Best regards,
>> Raye Rivera
>>   QA Manager * Canoga Perkins * 818-678-3872  * 
>> [log in to unmask] Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
>> Sent: Thursday, August 29, 2013 10:35 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blowing Smoke
>>
>> I think what I'm going to try next is two wirewound resistors glued 
>> together with some ceramic paste, or maybe just build a hammock 
>> between them with some aluminum foil.  Then try a drop or two of the 
>> liquid they use on model trains to simulate smoke.  If that doesn't 
>> get me anywhere, then maybe the heating element from an e-cigarette.
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
>> Sent: Thursday, August 29, 2013 1:17 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blowing Smoke
>>
>> Wayne - agree.  That's why I pointed you to Gentex.  It's optical. 
>> Used to be that all commercial aircraft had these detectors from 
>> Gentex
>>
>> Steve C
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
>> Sent: Thursday, August 29, 2013 1:03 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blowing Smoke
>>
>> In an ionization-based detection system (technically illegal in my 
>> application because of the radioactive source required), you can 
>> check sensitivity by looking at the leakage current through the 
>> ionization chamber.  Most of these "in circuit test" systems simply 
>> put a resistor across the ionization chamber and measure the time it 
>> takes set off the alarm.
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
>> Sent: Thursday, August 29, 2013 12:51 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blowing Smoke
>>
>> Wayne,
>>
>> That is a good point about the smoke detectors, since there are two 
>> types
>> - the ionization types and the particulate types that work by 
>> scattering of light.
>> Look at FAQ #3 at this site -
>> http://www.gentex.com/fire-**protection/technical-support<http://www.
>> gentex.com/fire-protection/technical-support>
>> It would appear that they have the calibration and degradation issues 
>> worked out.  I may still know some people there, but not sure how 
>> much help that would be in this situation.
>>
>> We used to ignite a ribbon of Mg to coat the inside of an integrating 
>> sphere with white powder.  If you can combust tiny performs of Mg, or 
>> nanofoil as someone else suggested, that seems like it might satisfy 
>> your combustion quantity issue - although may create another issue 
>> with transport and handling....
>>
>> Steve C
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
>> Sent: Thursday, August 29, 2013 12:33 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blowing Smoke
>>
>> Hi Dennis-
>>
>> Yes, as you and Richard have pointed out, calibrating particle 
>> sensors is not un-mapped territory.  The systems are accurate and 
>> worthy of withstanding the rigors of lawsuits.
>>
>> But we can all see that there is a huge gulf between that kind of 
>> calibration and the other end of the spectrum, such as seeing whether 
>> a smoke detector is working OK.
>>
>> Another point in that gulf is a counter designed to control a HEPA in 
>> a room where a person has allergies.  For that, they don't use a 
>> laser for illuminating the particles, they just use an IR LED.  Hence 
>> they don't know if they are looking at one giant particle or a bunch 
>> of tiny ones.  But they actually appear to be useful anyway, and the 
>> cost for the sensor from DigiKey is $12.  Sharp tells you right up 
>> front on the data sheet that the LED will fade over time, by as much 
>> as 50%, with a corresponding drop in sensitivity.  Also, the 
>> calibration curves provided in the data sheet show a very wide range of "typical" calibration slopes.
>>
>> So my gut tells me there should be some way of making a repeatable 
>> experiment that could be used for comparing these cheap sensors to 
>> each other and to watch the degradation in performance vs. time.  I 
>> need to vaporize a defined amount of material in a closed volume. 
>> Turns out to be more challenging than I thought!  It seems the 
>> diffusion of the vaporized material is actually the easy part. 
>> Complete combustion of a defined amount of material is hard.
>>
>> Wayne
>>
>> From: Dennis Fritz [mailto:[log in to unmask]]
>> Sent: Thursday, August 29, 2013 11:27 AM
>> To: Wayne Thayer
>> Subject: Re: [TN] Blowing Smoke
>>
>> Good luck on this one, especially the "The idea is a cheap sensor" part.
>>
>> Particle measurment in either air or liquid is pretty well developed.
>> IEST is the standards organization and there are also IEC 
>> international regulations/certifications
>>
>> I googled "air particle counter calibration" and a lot of stuff came 
>> up - most all probably too complicated for what you need - "cheap". 
>> However, this link gives some background on your problem and a bit of 
>> "who certifies what".
>>
>>
>> http://www.particle.com/wp-**content/uploads/downloads/**
>> 2012/02/WP-MET-ONE-ISO-<http://www.particle.com/wp-content/uploads/do
>> wnloads/2012/02/WP-MET-ONE-ISO-> 
>> 21501-Calibration-of-APC-from-**Metrology-Perspective-US.pdf
>>
>> Good luck.
>>
>> -----Original Message-----
>> From: Wayne Thayer 
>> <[log in to unmask]<mailto:w**[log in to unmask]<[log in to unmask]
>> COM>
>> >>
>> To: TechNet <[log in to unmask]<mailto:TechNe**[log in to unmask] 
>> <[log in to unmask]>>>
>> Sent: Thu, Aug 29, 2013 10:06 am
>> Subject: Re: [TN] Blowing Smoke
>>
>> To answer previous question:
>>
>>
>>
>> The idea is a cheap sensor.  3rd world homes are notoriously smoky 
>> due to the
>>
>> cooking fire and due to kerosene lamps.  Most of the smoke is carbon.
>> There are
>>
>> lots of ideas for improving these homes (like LED lights with solar
>> rechargers)
>>
>> so we can "improve their lot" by making it more healthy for kids to 
>> study inside
>>
>> (or maybe so they can buy stuff on the internet?).  Anyway, the aid 
>> groups want
>>
>> a way to see what the bang for buck is in improving the indoor 
>> environment, so
>>
>> they need a sensor.  These sensors work by shining an LED or laser 
>> through an
>>
>> air stream, and measuring the amount of light which is reflected 
>> off-axis by the
>>
>> particulates in the air.
>>
>>
>>
>> How does the bicycle pump (actually I'm imagining a disposable 
>> plastic
>> syringe)
>>
>> pick up a defined amount of cigarette smoke?  Maybe arrange a fixture 
>> which
>>
>> leaves the cigarette burning and allows the smoke to just rise into 
>> the open end
>>
>> of the syringe for a set amount of time, then put the plunger in. 
>> Might
>>
>> work-cheap to try!
>>
>>
>>
>> As to the other suggestions, such as the nichrome wire, I keep coming 
>> back to
>>
>> needing some kind of heated basket so I can make sure I burn 100% of 
>> whatever I
>>
>> put in there.  A circulating fan and Brownian motion should make the 
>> environment
>>
>> pretty uniform, although with the tests I've been doing, I get a 
>> spike with an
>>
>> exponential decay as the particles settle.  Still, the interior of 
>> the 5 gallon
>>
>> bucket appears pretty uniform, even though the peak duration is only 
>> about
>> 40
>>
>> secs.
>>
>>
>>
>> Wayne
>>
>>
>>
>> From: Inge Hernefjord
>> [mailto:[log in to unmask]**<mailto:[log in to unmask]**?>]
>>
>> Sent: Thursday, August 29, 2013 4:45 AM
>>
>> To: TechNet E-Mail Forum; Wayne Thayer
>>
>> Subject: Re: [TN] Blowing Smoke
>>
>>
>>
>> Don't laugh now, I am serious. A kind of cycle pump, but with a very 
>> small
>>
>> diameter nozzle. Pull the handle and suck a second sniff of cigarett 
>> smoke,
>>
>> continue pulling handle until pump is filled with air/smoke mixture. 
>> Now press
>>
>> handle slowly and you get a constant stream of mixture. Simple and cheap.
>> Guess
>>
>> the nozzle should be fractions of a millimeter.
>>
>>
>>
>> Inge
>>
>>
>>
>> On 28 August 2013 08:07, Wayne Thayer
>>
>> <[log in to unmask]<mailto:w**[log in to unmask]<[log in to unmask]
>> com>
>> ><mailto:wt**[log in to unmask] <[log in to unmask]>
>> om<mailto:[log in to unmask]**?>>>
>>
>> wrote:
>>
>> OK, here's another problem I've been playing with (although it has 
>> little to do
>>
>> with IPC mission, it might be related).
>>
>>
>>
>> I am trying to build a system for measuring airborne particulates for
>>
>> humanitarian organizations looking for inexpensive ways to 
>> measure/monitor
>>
>> indoor air quality.  There are cheap sensors available which might do 
>> the job,
>>
>> but they would need periodic re-calibration.
>>
>>
>>
>> So I need a controlled, extremely small amount of smoke.  At first, I 
>> thought
>>
>> this would be trivial:  Find a cheap part at DigiKey and put too many 
>> watts
>>
>> through it.  Way too much smoke and too little control.  Then I tried 
>> burning
>>
>> thin wires.  Too irregular because sometimes they incinerate 
>> completely and
>>
>> other times they find a tiny defect and just burn that until the wire 
>> stops
>>
>> conducting.  Then I tried just heating the wire enough to burn off 
>> the
>>
>> insulation.  Still too irregular!  I did just a few experiments and 
>> got 30%
>>
>> variation.
>>
>>
>>
>> Now I'm starting to think maybe a tiny piece of paper on an 
>> automotive cigarette
>>
>> lighter.  That's a lot of power to get that glowing, and it is not 
>> convenient to
>>
>> attach to.  Any other ideas?
>>
>>
>>
>> Wayne
>>
>>
>>
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