Joule Thief 101

[tinman]

I will take this one step further because it's annoying.

Why did I put "missing" in quotations?

Let's look at the question again:

Is that question asking you for specific values?  The answer no.  Now can you understand the question?

Here is an analogy to show you how ridiculous your balking is:

Supposing you are in grade 6 and the teacher says to the class,  "Write up a short story describing how you fill up your car with gas at a gas station."  It's a test for the children in grade 6 to see if they are capable of describing something in a logical order and to see if they can put sentences together properly.  It's not a skill-testing question to see if they know how to pump gas.

Now if a student complains that he can't write the short story because, 1) the make and model of the car is not defined, 2) how empty the gas tank is is not defined, 3) the type of gas is not defined, and 4) the brand of the gas station is not defined, then clearly there is a problem with that student.

That's exactly what you are doing when I ask you how the resonant frequency of a wine glass is determined and it's ridiculous.  The question can be answered without specifics.

So you can answer the question by filling in the "missing" physical parameters by yourself, or you can answer the question as it was posed to you just like the kids in the class can write the short story about how to pump gas without specifics.

I will return to this subject in four to eight weeks if you can't answer the questions.  Simple, basic questions can be answered with simple, basic answers.

MileHigh

Your in dream land MH

How is the resonant frequency of a wine glass determined?

The list of specifications that will determine the resonant frequency of a wine glass is a !Mile! long.
When working out how to determine what the resonant frequency will be ,you need that full list of specifications,and by building the wine glass to those specifications,then hopefully you will be some where in the ball park.
E.G-if you want a wine glass to resonate at a determined frequency of say 440Hz,then you need all the information about the makeup of the wine glass in order to construct that wine glass to resonate at the determined frequency

Now if you want to know the actual resonant frequency(the frequency that has already been determined by it's physical and chemical parameters) of a wine glass,then i would think the easiest way to do that would be to give the wine glass a quick tap,and hold a microphone !that is hooked to a scope!,close to the wine glass,and see what the vibrational frequency is on your scope. You would then know !what! the determined frequency of the wine glass is.

It;s the same when building switchmode power supplies. First you determine what output power you need,and then you build that power supply that will deliver the required output using known specifications.So the only way to know how to determine that output,is by using known specifications of the components and makeup of that power supply.
But if you want to know !what! the actual power output is of an already built power supply,then you can simply do some load tests to acquire that information-as the determined output was already set when the power supply was built.

Maybe you meant- how can we find out what the resonant frequency of a wine glass is?,as that frequency was already determined when the wine glass was constructed.
If so,then i have answered that question above-->and you should try and word things correctly MH,as it would save a lot of confusion for everyone else.


Brad

[tinman]

Just to add to this a little bit

https://www.google.com/search?q=detrmined&ie=utf-8&oe=utf-8#q=how+to+determine+the+resonant+frequency+of+a+wine+glass

The consensus seems to be to ping it and measure it with a tool,, no calculating it  

Which is not determining the frequency but rather measuring it.

So the CORRECT question should of been,, how can you FIND the resonant frequency of a wine glass.

Just my tuppence worth

Bingo
Spot on webby.

Brad

[tinman]

NOPE!

and here is why.

There is not ONE frequency,, there are many,, so I was wrong, the question should be "A" resonant frequency not "THE".

It is a silly question,, but that has made me think of things in a little different way,, to me that is something that was learned.

Webby
I do not think the wine glass has multiple resonant frequency's--i believe it will have only one.
The force that causes that resonant frequency in the wine glass can have multiple frequency's that are divisions or multiplications of that resonant frequency of the wine glass.
EG,if the wine glass has a resonant frequency of say 400Hz,then we should be able to tap that glass at 200Hz,and the glass should still resonate.
This is much the same as the kid on a swing. Even if we only gave him a push every second swing,his resonant frequency will still remain the same as if we push him every swing.


Brad

[tinman]

Here is a very good example of mechanical and electrical resonance in an electric solenoid motor i built years ago for another project.--watch from 4:00 on.

In the bottom of the solenoid cylinder there is a S/S spring. When the electromagnet switches off,the PM drops onto the spring--you will see the conrod oscillate up and down when the PM hits the spring--this is during low frequency cycles. When i start raising the frequency to the solenoid,you can see and hear that the matching frequency to the spring has still not been met. At the last adjustment of frequency,you can hear and see that the rise and fall time of the PM is now exact to that of the springs reaction time-->the PM and spring combination are now at there resonant frequency.
The spring is now pushing the PM back up at the very same time the solenoid fires,and the whole system smooths right out.

https://www.youtube.com/watch?v=Z4VJG8-9izQ


Brad

[MileHigh]

Here are the two questions again:

How does a wine glass resonate, what is the mechanism?
How is the resonant frequency of a wine glass determined?

All of the whining and complaining and moaning and making up excuses is just you saying that you don't truly understand what resonance is because if you did you could answer both questions without batting an eyelash.

So right now you are unable to answer the questions, period.  I will answer them in four to eight weeks.  Now if you wanted to undertake to learn something on your own volition and came back and answered them correctly that would be great.

MileHigh