Rick's b.log - entry 2022/10/10

Linguine lengths

I didn't expect it to get quite a long as it did, but...

The incorrect and frankly bizarre linguine length on The Register is 14cm.

Actual real linguine (multiple brands, but Panzani and Barilla tested, are approximately 25cm.

And when cooked? 33cm. Three pieces measured, margin of error ±½cm.

Raw and cooked linguine (Barilla).

A T-shirt for Samhain

Now, I don't really like paying a shade under twenty euros for a custom T-shirt from Amazon, but...
Spooky, check. Blood, check. Sarcasm, check. Cat, check. Cat-as-main-character, oh hell check.

Oh kitteh, what hast thou done?

Choccies!

This might explain my built-in shock absorber.

Oscilloscope and mains hum

Anyway, it's not too noisy (pretty much a flat line) when lying on the shelf, coming alive as you can see when I touch it. I don't recall the settings, but I'd feel pretty certain that it's me picking up 50Hz hum from the mains wiring.
The thing is, what's with the weird pattern? It's not so much a sine wave as faulty Toblerone. Interestingly, it's mirrored too. Both ends of the signal exhibit the same general behaviour. Any ideas?

Bip, bip, bip...

You know you're an insufferable nerd when...

Did I think "Oh, that's pretty"? No.
Did I think "Oh, I ought to mow that"? No.

What I thought...

Well, that would be an interesting source of randomness.

Your comments:

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Anon, 10th October 2022, 21:08

Have to say, that linguine (the bottom one) looks more like a tapeworm.    (What happened to the comments earlier? Did they get turned off, or was it a server fail?)

Rick, 10th October 2022, 21:27

Comments are automatically disabled when the server runs out of disc space. It happens from time to time. Not a big deal.

David Pilling, 11th October 2022, 01:57

You could feed your little yellow flowers into rngtest and Dieharder to see if they are random. There are patterns in nature - relevant ones - fairy rings.    Yeah mains is rarely a pure sine wave. There's the question of you being a capacitively coupled, possibly to more than one source. Mostly I would guess is all the stuff than is connected to the mains and adds interference. Man next door has big motor with thyristor control.  Chance to use FFT mode on your 'scope and explore the frequency spectrum.

Zerosquare, 11th October 2022, 02:38

Yes, what you are seeing is waveform distortion caused by overtones (sinusoids whose frequency is an integer multiple of 50 Hz). Those are created by non-linear loads, like light dimmers or switching-mode power supplies. Capacitive coupling can also alter the signal shape, so it's probably not as bad as it looks on the scope.    I'd be very surprised if that old school CRT oscilloscope had a FFT mode :)  But since the signal frequency is low, you can record it with a sound card and analyze it using Audacity or some other audio software.

Anon, 11th October 2022, 22:54

RFI on the mains... the bane of every audiophile's life.    You can buy RFI filtered mains strips (and wall sockets). Amazingly they're not snake oil, they actually do make a difference. Particularly if you've got a cupboard full of servers spewing RFI back onto the mains.

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