The pattern that John Larkin sees looks like that. He;'s not the world's most objective observer.
Not to you - those personality disorders do play hell with your perceptions.
Jamie's contributions aren't impressive.
Depends what you mean by a flame war, and perhaps what you mean by "technically competent". There are certainly a few ill-tempered exchanges here between people who do know what they are talking about when they are talking about electronics.
Just out of curiosity: isn't spark detection unnecessary, as it might be too late? One will just know the reason of the fire, but, err..., they will know about that anyway, running like hell from the plant?
Best reagrds, Piotr
?
Not at all. It's quite easy to get rid of them without even interrupting pr oduction, if you do it right. The air is going by at 10-30 m/s, so if you p ut a diverter a few metres downstream, there's plenty of time to open it an d dump the spark someplace harmless. Then you shut it again and production goes on, minus a pound or two of cotton.
Cheers
Phil Hobbs
I will try to get the last word by apologizing. You guys are right. My bad. Sorry, Jamie.
Horrible. Fun though. Why not a charge pump? Costs an extra transistor and cap, probably cheaper than the inductor and definitely more efficient than the zener.
Doing stuff that costs next to nothing is an interesting challenge.
Cheers
Phil Hobbs
[...]
Wow! That's _truly_ retro! Wonder what kined of tuned loop you need to get a signal with that detector?
More seriously, isn't cotton dust one of those that, given the correct air mixture, doesn't just burn but goes BOOM! all over everything? Or is that prevented through some other mechanism?
Jes' curious...
Frank McKenney
The problem with parts minimization is that you can create a circuit where, for instance, the value of one resistor controls two important parameters. Then you can be trapped. Things like quad r-packs can be another kind of trap.
Fortunately, 0402 resistors cost milli-cents. (Not to be confused with Aunt Millie.) Usually I'm building TIAs with BF862s and OPA140s or ADA4899s or something fancy like that, so 324s are a fun challenge.
Cheers
Phil Hobbs
On a sunny day (Fri, 04 Dec 2015 09:46:32 -0600) it happened Frnak McKenney wrote in :
The main problem with the ferrite antenna is not too little sensitivity, but too much, as then every light switch flipped triggers the alarm. This is better with an outside antenna, but it was designed to alert me so I could disconnect the outside GPA (CB) antenna, often in middle of the night in pyamas when it was raining,
I was wondering if you could not detect those 'hot spots' with that 199 $ FLIR camera, But I guess he needs a whole lot of sensors along the tubes that carry that cotton. Maybe use plastic IR transparent tubes... :-)
Those are pretty cool. I've never used one myself.
Cheers
Phil Hobbs
Well, I used to make crystal radios for light myself. ;)
Yup, cotton is almost pure cellulose, and cellulose dust is bad news in explosive concentrations.
This is in clumps of fibres, though, which don't burn as fast as dust. The dust concentration must be pretty low, though I don't know how low.
Cheers
Phil Hobbs
Too slow and too expensive, plus you don't need to know where the hot thing is, just that there is one. Apart from the $5 PD, my BOM cost for this board is under 2 bucks.
Cheers
Phil Hobbs
>
Oh no worries John S. You grow thick skin here, or you don't last. (And we are all human and get frustrated and cranky.) But it's gotten so nice lately, and I would like to encourage it. I sometime think there is a critical mass of politeness or a-holeness. and if we get above that, then being polite becomes the standard. Of course it's totally fine to disagree. Look at Phil A. He still tells you when he thinks you've got holes in your head, but he does it without all the previous invective.
Anyway this is mostly a selfish desire. I log on to SED (via google) and I see all these nice threads that I haven't read. Oh boy! I think, electronics fun. If it happens that they have turned into flame wars, I'm disappointed.
George H.
Yes, UV TRON is their line of flame sensor tubes:
Pretty similar to a small GM tube.
--sp
Unfortunately the mounting cost for resistors is usually counted as
*much* higher than the parts cost, so I make extensive use of 4-resistor packs. Even if you only use two or three of the four it can be cheaper.--sp
I agree. I will try to do better. You are a pretty good example to follow. Thanks.
It isn't selfish. Others have expressed the same wishes and, again, I agree with you.
John S
Huh, have you bought any those? (how much?)
I wonder if I could do the photo-electric effect with a few UV led's?
George H.
If you have a good pick-and-place, and the reel is already mounted, placement is not expensive. So the trick is to try to use the fewest different part values on a board. But using discretes lets you get out of trouble if a value is wrong.
For no-brainers, like pullups, there's no downside to using packs.
You can make an interesting range of resistor values and divider ratios from quad packs.
Sure thing. That's production's worry, though. ;)
Cheers
Phil Hobbs
It's been a long time- I *think* around $15-$20 each in smallish quantities.
The spectral response curve is down to 1/10 at 230-255nm depending on the type and most of the 'UV' LEDs are more like 400nm, so no, a malicious element would not be able to fool the flame detector and cause a massive explosion with a UV LED flashlight. These guys
The Hammamatsu A type is very insensitive to even the strong Hg line at 253nm.
--sp
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