Semi-OT, Unimportant question to soothe my curiosity ...

[bradpa77]

Please forgive me if this is way off topic but I was just curious about this.

I'm a mechanical engineer and at college one of my electrical engineering friends said this to me:

"If you play your walkman with the volume up the whole way, you will get more battery life than you would if you have the volume at a lower level"

His line of reasoning had to do with the basic equation for power. He said that the volume knob basically adjusts the resistance in the circuit. The higher the resistance, the less current through the circuit and the lower the volume in the headphones.

He also mentioned that the higher resistance required more power draw from the battery which drains the life faster.

Is any of this true?

 

[cbarn24050]

No.

 

[Skogsgurra]

No. Completely false. All these devices drain battery more or less in proportion to volume setting (and background light setting).

He may have confused class A and class AB (or B) operation with volume control setting. But they have nothing to do with each other.

One of the dangers of being "half informed".

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[felixc]

Your colleague was pulling your leg.

 

[richs]

Hiya-

Good to see that some traditions haven't changed. When I
was in college, we used to give the Mechanical Engineers
a chart to convert cycles per second to Hertz......

We used semi-log paper so it wasn't a straight line.

Sigh, now a days, you are hard pressed to even *FIND*
semi-log graph paper.

Cheers,

Rich S.

 

[OperaHouse]

When I was in college the dorm rooms had stand alone wood and formica cabinets with metal handles to store clothes etc. There were some people messing around with his stuff. He wired the two metal handles up to a wall outlet. Not wanting to harm anyone, he wired a 100 watt light bulb in series to limit the current.

Your friend is likely not pulling a prank on you, he is just plain stupid.

 

[zeitghost]

Did the bulb light up... )

 

[richs]

In my college dorms, they had resently gotten some carpeting
in the hallways, (heaven forbid in the rooms). In Fresno,
it gets so dry in the winter time, static was a real
"gottcha". I would swipe a fluorescent tube from the bathroom,
scuff along the carpet and discharge the tube on the nearest
doorknob. Used to "impress" the other dormies. "impress"
is not the right word.

And yes, it did indeed flash brightly.

Cheers,

Rich S.

 

[IRstuff]

So a 100 W bulb is like a 1 ohm series resistance. The bulb probably didn't light up, but anyone holding it probably did

TTFN

 

[logbook]

The point probably got scrambled in the translation. The efficiency of an output stage can increase when it is driven hard. That does not mean that it dissipates less power; what it means is that it dissipates a lower percentage of the power.

If the output power is 100mW at 10% efficiency then you are taking 1W. If you go to 500mW but the efficiency is now 20% that is still more power drawn (2.5W).

 

[dontthinktwice]

When I was in school (just over a year ago), we had the hertz to cycles per second chart up on the wall.

 

[richs]

Thanks dontthinktwice!

Good to know that there are some real traditions in
engineering......

Shoot, for me that was 30 years ago now. I hope that
your graph was also on semilog paper. The log curve helps
hide the correlation for those not initiated.

Cheers,

Rich S.

 

[geekEE]

http://www.brainerdham.org/Tips/CPS_to_Hz_conversion.html

Learn it. Know it. Live it.

 

[IRstuff]

TTFN

 

[itsmoked]

That's rich!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[analogkid2digitalman]

richs:

Quote of the day over at

http://www.rfcafe.com/

"The joy of engineering is to find a straight line on a double logarithmic diagram."
- Thomas Koenig

That must Hertz


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"It's the questions that drive us"
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