science project

OK, I always wanted to record the sound from my waterfall and do a similar analysis... (My kids are young there's plenty of time.) Or record the sound of rain drops on a tent/ tarp. Can you figure out the rain drop size from the noise spectrum?

George H.

The waterfall and the fireplace may have near-periodic components. Both may also have unexpected high-frequency components.

When I was a kid I used to hook a PMT+crappy telescope up to headphones and listen to light. I mostly got 60 Hz and harmonics from street lights. I tried stars but got nothing. In principle I might have discovered pulsars.

John

Tim

On a sunny day (Wed, 16 Dec 2009 09:02:59 -0800 (PST)) it happened George Herold wrote in :

There exists software that can figure out what is typed from the sound of keys pressed on a PC keyboard.

"John Larkin" schreef in bericht news: snipped-for-privacy@4ax.com...

Ever found an article on the net that told the "randomgenerator" to be some wellknown christmas tune. I opened two different types. One seemed to be some unknown tune, the other the rattle of a real pseudo random generator.

petrus bitbyter

Last time I did the math, I think I concluded that 120 Hz is a harmonic of 60 Hz.

John

But the lamps don't know for which half-wave they should not glow :-)

On a sunny day (Wed, 16 Dec 2009 14:03:02 -0800) it happened Joerg wrote in :

But maybe the lamp had a half defective triac dimmer.

Wow you got to play with PMT's as a kid! (or does kid mean 1/2 your current age?) We use a PMT to measure single photons in a two slit interference experiment. We added a 'clicker' that makes a clikc at every output pulse. It's nice to hear the Poisson noise. (Just like Geiger counter clicks). But it only works for fairly low count rates. My guess is their was too much light from the stars (count rate greater than a few thousand per second.) which is why you heard nothing. (Or was this an early SETA attempt?)

George H.

keys pressed on a PC keyboard.- Hide quoted text -

Really? How does that work? Does it have to 'calibrated' for every keyboard? Does it depend on which finger I'm using to push the keys?

George H.

Alas, some DO know. The pointy-ness of the electrodes on a fluorescent tube can make an asymmetry in the strike voltage, and that causes ballasts to hum and overheat. I've fixed noisy fluorescents by reversing one of the tubes end-for-end.

Nowadays, I put in electronic ballasts instead.

On a sunny day (Wed, 16 Dec 2009 14:33:12 -0800 (PST)) it happened George Herold wrote in :

Has something to do with cryptography. For a start, I think that from the frequency (I mean in this case how often a specific character is used), combined with the sound spectrum that pressing a specific key makes, you can already decipher things. There was some paper on that, but I have no idea where, even if I have it, and where I stored it, and under what name, if I have it. sci.crypt would be a good place to ask.

I can clearly hear different sounds coming from different keys on my keyboard (Logitech). You could train a neural net too I guess, even a human one, to learn to recognise the key strokes.

But my PMT power supply used a half-wave rectifier. It made its own 60 Hz hum.

I made a flashtube LIDAR, too. The HV supply used a neon sign transformer and the regulator was a flashlight battery driving a 1B3 heater through a rheostat, with a long plastic shaft to the knob of course. Turn the knob to set the HV.

Sort of amazing that I'm still alive.

John

Age 10 or so, glory days of WWII surplus. A 931A could be bought from Fair Radio Sales for around $3. A CRT radar indicator was $5, and you could buy an entire under-wing radar pod for $75. Plus, my uncle Sheldon had been a radio operator in the war and he had an entire shed full of gear he had stolen from the Army.

They had a lot of cool radioactive stuff I should have bought, too.

We use a PMT to measure single photons in a two slit

Well, I had bad optics and city lights and didn't know where to look. I wonder of optical pulsars make enough light that an amateur, say 6", telescope and a good photodector could see the pulses.

I did hear some cool VLF atmospherics, and measure electric fields from clouds. Built a Kerr cell using nitrobenzene, which is apparently pretty toxic. Somebody was murdered with a dish of the stuff in a Nero Wolfe mystery.

Hey, put a pizza pan out in the rain and listen to the smacks as charged raindrops hit it.

John

Yuck. No regulator? I made my first HV regulator with scrapped color TV parts. The tubes were free, in contrast to anything semiconductor. Courtesy of bulk waste pickup days that they had every 1-2 months in Germany where people could place all their dead TVs and stuff curbside. The day before I always oiled my bicycle chain and pumped up the rear tire real hard in case I decided to haul a whole TV set home. Which to my mom's horror I typically did.

Today the federales would probably come "visit" if you did that :-)

Yep, Vaisala does it, its pretty neat:

Someone's already captured the resulting data of your exact setup and saved it as a sound file (plus they added a video to go with it). The results are completely atonal, unsynchronized, and random sounding.

Bob

Music is wonderful. It keeps the majority of the mindless humans on the planet indoors, amused, anesthetized, and mostly out of trouble.

John

=BF=BDOr

re out

"> Hey, put a pizza pan out in the rain and listen to the smacks as charged raindrops hit it."

Excellent, Phil H. is right you are a wild man!

Will the rain drops only be charged when the thunder head is moving through? Sounds like a project for southern Florida.

Under the pie pan will live a current amp. (discharge the pan through a resistor and TIA opamp ? Or is there a better way?) and a microphone to measure the sound noise.

George H.