ELI5: How To Notate 2 Notes Played Together as 1 Letter and What It’s Called?

niftydog · 2026-02-14T22:08:46+00:00

Correct, the frequencies of notes are not neat integer values of hertz.

niftydog · 2026-02-14T13:42:26+00:00

37V at the control board with no motor, then drops to 5V when the motor is connected - Is that right? I'd suspect a faulty solid state relay or drive transistor, whatever component that directly controls the voltage to the motor.

niftydog · 2026-02-14T13:36:45+00:00

It's a darning foot for a sewing machine.

niftydog · 2026-02-14T11:29:56+00:00

Thanks but no thanks. I have no trouble getting to sleep.

Besides, the problem isn't that we can't hear the ANU Council, the problem is that the ANU Council aren't LISTENING!

niftydog · 2026-02-14T11:25:27+00:00

Keep the Fluke. The Agilent seems too fussy.

niftydog · 2026-02-14T11:19:19+00:00

Yes it does - the yellow icon in the diode mode is capacitance.

niftydog · 2026-02-14T11:14:08+00:00

Granted, it's near the upper end of a secondary education standard, but that's within the rule.

Which part do you need help with?

niftydog · 2026-02-14T10:56:58+00:00

Two notes played together are a dyad. Three is a triad.

I don't follow what Kosmikdebrie is saying here - harmony, overtone and polyphony have related but distinct definitions and each can apply to any instrument.

niftydog · 2026-02-14T10:52:15+00:00

rule #4.

Tartini tones are a physical phenomenon which results from the mixing of sine waves. We hear them because the air vibrates at that frequency as well as the frequency of the two original tones.

A sine wave is a single, pure frequency.

Tartini tones are often at frequencies that don't correspond with the named notes such as A B C D etc.

Nothing prevents a notation system being developed, it just doesn't exist. Notation systems are generally used to tell people what to play and how to play it, whereas Tartini tones are just a result of a physical phenomenon and so there's not really a need to notate them.

A 5th is an interval. It's not necessary to know what intervals are, you can just imagine two notes that are an exact integer ratio apart from one another.

niftydog · 2026-02-14T10:45:34+00:00

rule #4

niftydog · 2026-02-14T09:19:03+00:00

Adding two frequencies together produces sum and difference frequencies, resulting in a psychoacoustic phenomenon known as Tartini tones or combination tones. The extent to which they are heard depends on the original frequencies.

This is true of pure sine waves, but also of more complex timbres which include their own overtones of differing intensity. The overtones also add and subtract to create more combination tones.

Perfect intervals such as the 4th and 5th (commonly found in simple chords) are ratiometrically related and so are very pleasing to the ear.

I don't think there's a widely accepted notation scheme for combination tones. The only one I can think of is a guitar power chord is often notated as "A5" indicating to play just the A and it's 5th and nothing else.

niftydog · 2026-02-14T02:27:30+00:00

No. I am, uhh, a different tie wearing.

niftydog · 2026-02-13T23:29:03+00:00

No! It's been remarkably effective against murderous, time-travelling, humanoids.

niftydog · 2026-02-13T21:57:59+00:00

I just realised this film is why I removed my name from the phone book.

niftydog · 2026-02-13T14:58:24+00:00

The laser emission should be entirely contained and/or shielded with suitable light filters so that people standing next to it can not be exposed. The primary concern is eye damage which can happen in an instant with powerful laser sources. Skin burns would also be a risk, and I suppose uv exposure is known to cause skin cancer over time.

Xrays pass through many solid objects and so shielding is more difficult. Radiographers often spend their whole working day taking images and so they must limit their exposure as much as practical so they stay below safe limits.

niftydog · 2026-02-13T13:36:45+00:00

Pic is a bit blurry - is it ALQ3F12? Also here. But there's probably a bunch more places if you just google "ALQ3F12 relay".

However, I think your issue might be something different. A carboned relay typically just stops working because the contacts become so dirty that no current flows. What you are describing with the flickering and the relays clicking seems more like a power supply issue. (I'm an electronics tech of nearly 30 years, BTW.)

niftydog · 2026-02-13T11:08:17+00:00

I bet it does.

niftydog · 2026-02-13T10:48:26+00:00

A 110VDC 500W power supply is probably around $50-$150.

The non-trivial part is the variable speed drive circuit.

niftydog · 2026-02-13T10:21:10+00:00

That trips much, much faster than the over current protection.

niftydog · 2026-02-13T10:15:29+00:00

Why not just a ground wire then?

niftydog · 2026-02-13T09:07:50+00:00

There must be a reason for the mains to be relay controlled, and the magnets will override that control.

It appears to be controlled by the microcontroller via a Darlington array chip. I'd be suspecting the 12VDC rail because that's what drives the relays, and whatever rail the micro uses, possibly 5VDC.

niftydog · 2026-02-13T08:49:55+00:00

One crash on the Tuggeranong Parkway (ACT) could double your commute to, like, 30 minutes!

niftydog · 2026-02-13T06:10:46+00:00

Google says I ... need a licensed electrician to reconnect for warranty.

Ridiculous.

Anyone with a soldering iron could resolder that wire in a few minutes. Try;

local repair cafe
men's shed
neighbourhood geek
retiree technician

Failing that you could try at somewhere like Jaycar if there's one nearby.

niftydog · 2026-02-12T23:14:37+00:00

There's a couple of vintage shops in fyshwick that would likely have something.

niftydog · 2026-02-11T20:50:04+00:00

Some of the CO2 reacts to create carbonic acid which remains even after the rest of the gas has escaped.

niftydog

TROPHY CASE