# How stuff works

Discussion in 'Off Topic [BG]' started by slobake, Apr 4, 2017.

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1. ### slobakeresident ... somethingSupporting Member

I really enjoyed @mapleglo 's thread about quantum physics. Do you want to twist your brain into a pretzel? It made me think that it would also be fun to talk about basic things like how do pickups work? Or maybe what is the principle behind an internal combustion engine or how do you sweat a pipe?
No limits of course I would only ask that you avoid technical jargon and explain things that all of us (especially me ) can understand.
Last night when I was pedaling home from work I started thinking about how the gears on my bike work. Okay, some of you might be rolling your eyes right now , that's okay you can post more complex things. I find some simple things interesting and there may be one or two folks who feel the same way.
Back to the bike. There are two sets of gears on a bike. In my case I have three gears in the front under the pedals and 8 gears in the rear on top of the rear wheel. I can shift gears to make it easier to go up hill or so I can go faster on level ground. That works by moving the chain to different gears.
It is all about the gear to gear ratio. If I have the front set to larger the gear with 44 teeth and the rear set to the smaller gear with 11 teeth that creates a 4 to 1 gear ratio. That means that my rear wheel will rotate 4 times for every rotation of the pedals. That enables me to go faster but also means I need to push harder when I pedal.
What if I head towards a San Francisco hill? I can set the front to the smallest gear with 22 teeth and the rear to the largest gear with 30 teeth. That will create a .073 to 1 gear ration. That means every time I turn the pedals one rotation the rear wheel will rotate .073 times. That enables me to rotate the pedals with less pressure but it also means it will require more rotations on the pedals to move the same distance it would when the gears are set to a 4 to 1 ratio.
Of course there are other factors like wheel and gear size, resistance created by the tires on the road and a host of other things. I decided to just talk about the gears to avoid the dreaded TLDR.
Looking forward to reading more. Have fun.

Last edited: Apr 4, 2017
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2. ### GornSupporting Member

Dec 15, 2011
Queens, NY
Here's a good place to start:

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3. ### slobakeresident ... somethingSupporting Member

Ama
Wow, it took me a lot longer than two minutes to write out how gears work and he explains the Big Bang Theory in less than two minutes.

4. ### GornSupporting Member

Dec 15, 2011
Queens, NY
He's not the best at explaining things in a way normals can understand but he's not bad. Neil deGrasse Tyson and Michio Kaku do a better job at dumbing down these concepts.

5. ### maplegloGold Supporting Member

Sep 7, 2013
phoenix, az
I've always been fascinated by how things work, from a very young age. My Dad was a mechanical engineer, and I remember relentlessly asking him about the way things functioned. I likely drove him crazy. It's helped me through life though, from car and home repairs, to building guitars. Now that I understand quantum mechanics, I think I'll build a perpetual motion machine. Anyone have any time crystals they want to sell?

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6. ### ZenG

Dec 13, 2013
Near the fridge
I'm fascinated by how stuff doesn't work just when you want it to.

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7. ### GaoleeOutta my way! I'm caffeinated!Supporting Member

I'm still trying to figure out how Lace Alumitone pickups work. And failing miserably. They explain it, but it makes no sense to me from an electrical or mechanical standpoint. So, I'm baffled.

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8. ### blastoff99

Dec 17, 2011
SW WA
Interesting, @slobake . I've more than once used the 'bicycle gears' example to explain how a CVT works... without the gears, of course.

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9. ### StumboWherever you go, there you are.Commercial User

Feb 11, 2008
Intergalactic Mind Space
Song Surgeon sofware rep.
Didn't Mr. Murphy expound on that law of the universe? Or maybe it's the multi-verse now?

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10. ### bluesblaster

Jan 2, 2008
just ask professor Whoopee, it always seemed to help tennesee tuxedo and his pal chumely

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11. ### megafiddle

May 25, 2011
It looks like it works on the same principle as a pickup that I believe someone here is working on. Someone may recognize it from my description.

The pickup used a heavy conductor as a sensing "coil" and a Lo to Hi Z matching transformer. I am guessing that the sensing coil in the Alumitone is using the aluminum that you see in its construction as the conductor.

The "current driven design" simply refers to the very low impedance of the sensing coil, where current is relatively high, and voltage is relatively low. This is contrast to the "voltage driven design" of conventional pickups where the voltage is relatively high and the current is relatively low.

The matching transformer is necessary to raise the impedance, and more importantly the voltage, to the level required by instrument amp inputs.

I found this photo from here:

http://music-electronics-forum.com/attachments/32577d1422093517-lace_alumitone2.jpg

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12. ### Killed_by_DeathSnaggletooth

Jan 2, 2015
heart of darkness
I used to browse HSW at random:

How Electric Guitars Work

but eventually got bored & started browsing the Crime Library website, extra morbid stuff in there!

BTW, if you know the Physics behind the disruption of a magnetic field by a metal wire, you're good to go, as far as how guitars/bass guitars work...

then there's the tiny aspect of the electronics, resistance of the controls, but even more complicated if it's active electronics

13. ### JACink

Mar 9, 2011
Spain
I can explain how a car works (at least in Spain).

1. You spend money and buy a car.
1b. You give money to the government for taxes on the car.
2. You spend money on registering the car.
2b. You give money to the government for taxes on the registry.
3. You spend money on putting fuel in the car.
3b. You give money to the government for taxes on the fuel.
4. You spend money on servicing and repairing the car.
4b. You give money to the government for taxes on the repairs.
5. You loose money selling the car.
5b. You give money to the government for taxes on the sale of the car.

And back to step 1...

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14. ### slobakeresident ... somethingSupporting Member

Did you ever wonder why Fender switched to split-coil pickups on the Precision Bass? Here is what I know but unfortunately I can't locate my source. No doubt some folks here know more about this than I do so feel free to correct me if I am wrong.
If you look at the photo below you will see that the strings run directly over the poll pieces.

What about new tires? You didn't mention new tires.

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15. ### slobakeresident ... somethingSupporting Member

Did you ever wonder why Fender switched to split coil pickups? No? Okay I will tell you anyway. I remember reading about this but right now I can't find my source. I know some folks around here know a lot more about this than I do so feel free to correct me if we need to set the record straight.
Look at the photo below. This is a 51 style bass from Japan. Notice that the strings run directly over the pole pieces on the pickup.

Next is a photo of a 57 Precision with split coils. Notice that the strings run in between the pole pieces.

I read that the amps and particularly the drivers back in the 1950's where being overwhelmed by the bass. Fender was forced to deal with a number of blown drivers. To remedy this Leo Fender came up with the split coil pickup. I won't go into the specifics of how a pickup works but the sound is produced by the strings passing over the magnetic field created by the pickup. Running the strings in between the pole pieces made the pickups less punchy and was not a hard on the 50's drivers. Modern amps don't have that problem but so many of us have come to love the split-coil tone.
A side note is that the split coils are also hum cancelling but Fender didn't talk about it much because they didn't want legal problems with Gibson and their PAF Humbuckers.
We have a 51 style Squier bass at our practice space. That bass responds a lot more to how hard I pluck the strings than my split coil P does. The 50's style also breaks up the amp a lot quicker. Some people might like that but I still prefer the sweeter (to me) split coil tone.

Last edited: Apr 6, 2017
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16. ### MJ5150Terrific Twister

Apr 12, 2001
Lacey, WA
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17. ### GaoleeOutta my way! I'm caffeinated!Supporting Member

That was in English, but I'm still baffled. There's got to be some kind of magnetic field for a string to disturb, or there's got to be a physical coupling for the vibrations to be picked up, like a piezo does. I don't know how you generate a high current/low voltage vs. high voltage/low current with a pickup. Time for some transformer study, I guess, because that's all a pickup really is. Or actually a very small generator.

18. ### megafiddle

May 25, 2011
I assume there must be a magnet of some type in the Alumitone.

A generator is probably the best analogy for a pickup. The principle is simple: if a conductor is sitting within a magnetic field, and the field varies, then a voltage or current will be induced in the conductor. The pickup is like a generator in that some mechanical motion is causing the magnetic field to vary.

The conventional pickup consists of a coil of wire sitting within a magnaetic field. You can think of the string as capturing some of this field. The intensity of the field is measured as flux. It is analagous to current in an electrical circuit. The magnetic flux finds an easier path through the ferrous material of the string than it does through air, so a portion of the flux is directed through the string.

Then when the string moves, the flux is dragged around with it and causes variations in the field where the coil sits. I find this to be a good simple way of looking at it.

Transformer principles don't really apply to pickups. In the case of a transformer, the magnetic field is not generated by a magnet, and the field variations are not varied mechanically. Instead, the field is produced by currents from an external power or signal source.

Regarding "high current/low voltage" vs. "high voltage/low current", you can think of a conventional pickup as consisting of an enormous number of individual coil turns all connected in series. Each turn in the coil picks up an extremely tiny voltage. Since there are so many turns and they are in series, the voltages all add up to a significant level. But since they are in series, the individual impedances also add up to a significant level.

The Alumitone (I believe) uses just a single turn of heavy conductor. You can think of this as an enormous number of individual coil turns all connected in parallel. You now have the same very tiny voltage of one turn, but the combined current of all the turns. (these turns aren't physically separate; it's just an equivalent circuit)

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19. ### GaoleeOutta my way! I'm caffeinated!Supporting Member

There's a small magnet at one end. They are very light, relative to the usual pickup. I guess the large aluminum bars are effectively the coil, and somehow the small magnet induces enough flux through the aluminum bar so that the string's vibrations are able to generate enough disturbance in that flux to create a current. It's just a very different way to do the same thing, according to the logic that works in my brain. Voltage/current just confuses me until I understand why the two methods would be different. The electrical theory behind the function is the same, as far as I can tell. So, I'm confused. But, it's been enough of an interest that I have been geeking out on it, unsuccessfully, for a long time. For what its worth, I have Alumitones in a guitar and a bass, and I like them very much. Whatever causes a pickup to have a specific "sound" is apparently in low supply in them. They are sensitive to pickup height and pickup location on the string far more than they would be if they had their own natural coloration. Using them is one thing. Understanding them completely is another.

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20. ### petrus61Supporting Member

My daughter and I teamed up for her last 4th grade science fair. Our chosen experiment was "How does an Electric Guitar make sound?". I had an old MM humbucker laying around, wired it straight to a jack and mounted it on a 2x4 with some old cheap tuners, three strings and a tin salt shaker for a bridge. The pickup was moveable so you could hear it at different places on the board as you plucked the strings. I plugged it into a small headphone amp. It was interactive, people enjoyed it and was one of the most popular exhibits at the fair. We of course had a big diagram, complete with images showing the magnetic field, etc. You wouldn't believe how many people said "I never knew that!". I also had a glass slide so I could mess around with it between talking

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