science project

Well, I try. Having ideas is like any other skill, you have to keep practicing.

I'd suspect they always have some charge. But try it!

Just a big resistor to ground and a decent fet opamp should work, with maybe some protection diodes. As the drop squishes into the pan, a zot of charge will be deposited. The nice Vaisalia paper has a graph of drop diameter vs velocity, so the charge zots should be in the millisecond, maybe less, sort of range, assuming the water's not very conductive. If there's a lot of charge, you might even get a spark at contact; I have no idea what the incoming voltages or the signs might be.

This would be fun.

John

Gotta be pseudo-random, most likely vis one of the many possible shift register schemes; all on a very dinky chip; cheap as all hell - the epoxy dab on top prolly costs more than the chip...

...and the lamps _still_ darken on one end.

On a sunny day (Wed, 16 Dec 2009 20:05:28 -0800) it happened John Larkin wrote in :

Well, yes, the majority perhaps. BBC was last week re-tranmitting that Stones concert where one of the Hells Angels, who were hired to do security, killed somebody... But then the Rolling Stones never were my choice of music..... Neither is rappers... They seem to be involved in killings a lot too.

On a sunny day (Thu, 17 Dec 2009 03:39:28 -0800) it happened Robert Baer wrote in :

Linux: cat /dev/random (You need to wait for system activity)

cat /dev/urandom

More info: man urandom

All at your fingertips.

[snip]

I would agree that many younger people could be classified as mindless because of the music they listen to.

However, Einstein, who loved music, certainly wasn't hindered by listening to or playing music. Also, look at the accomplishments of someone like Mozart. In fact, to put it into perspective, when Mozart was my age he had been dead for 18 years.

Bob

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John L thinks anything he doesn't like is bad for the general population.... closet liberal ?:-) ...Jim Thompson

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Have you read the chapter in the Feynman lectures about charge separation in thunder storms? (Chapter 9 vol. II) I was looking at it this morning. Turns out the charge on the rain changes sign! It's positive in the center part of the cloud where the rain is heavy and negative out near the edges where the rain is light. I was wondering if a fine mesh might be better for collecting the charge rather than a solid plate.... Will the rain drops bounce off the plate without depositing all the charge? Ahh all sorts of fun things could be tried. This also might be the first instrument I build with a ground connection that is a rod hammered into the ground! Precipitation in my neck of the woods will be of the white fluffy variety for the next several months.

I've read a few of his books but not The Lectures.

I was looking at

I suspect that a nice solid SPPLATT!! (credit sound effect to Jorge) would transfer most of the charge. Rain is mildly acidic hence conductive, and the capacitance of a drop will be a small fraction of a picofarad, so the discharge time constant should be small compared to the mechanical SPLOOSH##! time. The waveform would reveal a lot about this.

Ahh all sorts of fun things could be

This is something Sloman could do at home. It's actually vaguely climate related yet would remove butts from chairs.

John

Those cause all kinds of optical noise and crap out to beyond 1 MHz...you don't care except when your IRDA devices quit working.

Cheers

Phil Hobbs

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Principal
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When John was a kid, triacs hadn't been invented :-)

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
                                             (Stephen Leacock)

At least they had moved from hand made to mass produced electrons in the US by then...

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On a sunny day (Fri, 18 Dec 2009 01:08:08 -0800) it happened Fred Abse wrote in :

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From:

The Triac evolved in three inventive steps: (1) The shorted emitter design by Aldrich and Holonyak (1958) (2) The remote gate by Gentry and Tuft (1963) (3) The Triac by Gutzwiller (1963)

So, 46 years ago. If John was 12 at that time, he would be 58 now.... I dunno how old he really is. But that site is interesting.

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"> I've read a few of his books but not The Lectures."

Oh I would highly recommend them... Sure they are now more than

40years old, but I can=92t think of any =91technical=92 books that I have read more often. Lotsa basic stuff that you can read quickly... but not too fast there are little =91gems=92 sprinkled around. Part of the reason I started dating my wife was that she had a near pristine collection in hard cover, and my softcover editions had a lot of wear from being schlepped around in my backpack.

George H.

message

But it took a whole long time until they made it into the stores inside dimmers. And then it took another few years until those became affordable to us folks of lesser means than Hollywood celebrities.

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Regards, Joerg

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On a sunny day (Fri, 18 Dec 2009 08:27:46 -0800) it happened Joerg wrote in :

I do not think so, I did a theatre dimmer console with triacs in early 1968. By then they had been available here in the shops for some time.

message

That's true, for certain values of "kid."

John

Well, yeah, but what was the price tag for this installation? For sure not under $10 where it needs to be for widespread acceptance in the residential markets.

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Regards, Joerg

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On a sunny day (Fri, 18 Dec 2009 14:00:29 -0800) it happened Joerg wrote in :

Oh, I dunno how much that dimmer console was sold for, several thousand I am sure. I was just the designer:-) But triacs were available for a few guilders sat that time. In dollars of those days maybe less then one $ (one Dutch guilder was around 4$). Plenty of diagrams in the hobby magazines too. I have the impression that you have been isolated somehow in the past in Germany from a lot of neat semiconductor and other stuff. I was just wondering tonight if that could have had anything to do with US policy to prevent Germany building weapons again after WW2.