Nuke Kid On The Block

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Watson A.Name - "Watt Sun, th 22 years ago

I replaced my smoke detector, since the old one was dated April, 1984. The new one says that it should be replace in ten years, and has the date of manuffacture. The old one said no such thing. There has been discussions here in the past about smoke detectors, and I had thought that the half life of the Americium was leess, so that after a dozen years it would become weak, but that's not true, it has a half life of over 400 years.

So I got on and googled for americium smoke detectors and found out a lot about them, mainly that the americium was located in the ionization chamber. The old one looks much like the one at this URL.

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I took the lid off the ionization chamber, but put it back on when I found that it was still spewing alpha particles and gamma rays.

I was thinking about removing the ionization chamber, but from what I've read, the ionization keeps it turned off, so removing the inoization source would cause it to go to constant alarm state. The circuit board has only a single chip, with just a bunch of resistors, a couple caps and a rectifier. THe chip as a house number on it, so it's probably a special chip. Pin 3 has been flipped up to contact the chamber, and some insulating goop has been put around it. A lot of the resistors are multi megohms. I'm not sure what would be needed to simulate the ionization chamber.

I was thinking that I might be able to use the piezoelectric tweeter to make a very loud alarm, for intrusion detection. The old smoke detector was made by First Alert, not much help. I googled for smoke detector schematics and came up with only one on Discover Circuits and it was the photon detector using a PIN diode. Maybe I could put a 10meg resistor across the chamber contacts to simulate it. Has anyone done this?

I wasnted to read the story about the kid who built his own reactor, but when I clicked on the link, the URL gave an error, so I googled for "Nuke Kid On The Block" and the story came up.

-- @@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@ ###Got a Question about ELECTRONICS? Check HERE First:###

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My email address is whitelisted. *All* email sent to it goes directly to the trash unless you add NOSPAM in the Subject: line with other stuff. alondra101 hotmail.com Don't be ripped off by the big book dealers. Go to the URL that will give you a choice and save you money(up to half).

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You'll be glad you did! Just when you thought you had all this figured out, the gov't changed it:

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dave 22 years ago

When the ionized smoke stuff obstructs / combines with enough of the ionized stream from the source, the voltage at the cathode changes. The change in voltage / current gives the alarm, usually a simple op-amp comparator. The newer detectors are normally optical types that look for particles, similar voltage dip type comparator. Some of the very oldest of the ionization type detectors used radium in the chambers. Should you open up one of these, do not lick the radium, that's bad. I have heard that radium is rather sought after tho' by the medical community, there may be a market for the stuff if the quantities were large enough, which isn't likely via smoke detector(s) . dave

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Tom Del Rosso 22 years ago

Hypothetically speaking, what if a little kid was to touch the tip of his finger to the pellet in a detector made about 1975?

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Tom Del Rosso 22 years ago

of

My finger's here too. :)

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Fleetie 22 years ago

"Hypothetically speaking", not a lot.

You'll be fine. 25-odd years later, you'll still here, aren't you?!

Erm, I mean, "Hypothetically speaking, someone who did that would be fine, providing the duration was short."!

Martin

M.A.Poyser Tel.: 07967 110890 Manchester, U.K. http://www.fleetie.demon.co.uk

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Don Bruder 22 years ago

The worry now is whether your finger is self-aware... Maybe it's not REALLY *YOUR* finger now at all, but a separate and sinister mind plotting world domination through digital manipulation?

Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004. I respond to Email as quick as humanly possible. If you Email me and get no response, see Short form: I'm trashing EVERYTHING that doesn't contain a password in the subject.

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Bill Garber 22 years ago

: > > "Hypothetically speaking", not a lot. : > >

: > > You'll be fine. 25-odd years later, you'll still here, aren't you?! : >

: > My finger's here too. :) : >

: >

: : The worry now is whether your finger is self-aware... Maybe it's not : REALLY *YOUR* finger now at all, but a separate and sinister mind : plotting world domination through digital manipulation?

Good One, Don. Heh Heh!

Bill @ GarberStreet Enterprizez };-) Web Site -

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Email - willy46pa @ comcast DOT net Change DOT to a dot to contact me

This email ain't infected, dude! Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.708 / Virus Database: 464 - Release Date: 6/18/04

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Rich Grise 22 years ago

He'd break out in festering pustules, and die a horrible agonizing death.

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Tom Del Rosso 22 years ago

And the rest of me is just it's reproductive organ. I can live with that.

Reminds me of a brilliant observation made by a guy from Portugal in a science group. Somebody asked what nails evolved for, and he (or rather his nails) typed an answer from their point of view. They said they had a population of 120 billion and growing, and they were just using the rest of the body as a support mechanism.

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Harry Conover 22 years ago

Worse still Rich, your eyeballs will pop out after about three days.... :-)

Harry C.

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Nuke Kid On The Block

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