Recent content by brentkiosk

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question about speakers and phase

If you reverse the polarity of one speaker in a standard two speaker stereo system that is set up to produce stereo, you will definitely notice the difference. At the mid point between the two speakers, it will sound sort of dead. As you move to either side, you will hear the closer speaker to...
- brentkiosk
- Post #2
- Jan 27, 2006
- Forum: Ask a Technical Professional
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So I've always wondered where molecular energy comes from...

This is a first law of thermodynamics situation. Writing heat flow, Q, in as +, and work done, W, by the water/ice as +, the first law is Q = W + delta U, where delta U is the change in internal energy. Since heat flows out as the water freezes (so Q is -) it's not the heat flow that does the...
- brentkiosk
- Post #3
- Jan 27, 2006
- Forum: Ask a Technical Professional
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Complex Fourier transforms and Quadrature detection

There must be someone more on top of this than I am, but you should be basically OK. Your system is essentially what's used in a TV or radio - an f-fr signal is produced over a frequency range convenient for processing. The final spectrum analysis is done by ear (for a radio) and the spectrum...
- brentkiosk
- Post #2
- Jan 26, 2006
- Forum: Ask a Technical Professional
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Need help with a Heat Load Study

For a first estimate for the knds of devices you mention, all of the energy could be taken as showing up as heat sooner or later. In most cases, the energy in goes pretty directly to heat - thermodynamically a PC just sits there and makes heat. Even the spinning disk, fan etc energy ends up as...
- brentkiosk
- Post #2
- Jan 25, 2006
- Forum: Ask a Technical Professional
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Why does AM radio suck so bad???

There are a couple of issues here. As has been pointed out, a lot of the power line noise has to do with the type of detection used in AM. Most of the noise appears as amplitude variations, so an AM radio is likely to detect it. FM detection if perfect does not notice amplitude variations...
- brentkiosk
- Post #14
- Jan 25, 2006
- Forum: Ask a Technical Professional
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Help Defining a Wave

Sillverpig's definition is pretty good. A wave is the solution to a wave equation (classical or quantum mechanical).
- brentkiosk
- Post #15
- Dec 3, 2005
- Forum: Ask a Technical Professional
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Geiger counters

That does make sense. The lighter particles in the stronger field would seem to make for a sharper edge on a bigger pulse. Maybe that's it. A long time ago, I worked with someone who was a great fan of GM detectors, and I know he explained more than just the basic operation. But, I've...
- brentkiosk
- Post #4
- Dec 3, 2005
- Forum: Ask a Technical Professional
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Geiger counters

Good question. It doesn't seem as if it would make any difference - you would get a discharge in the gas when it was ionized with either polarity. Maybe it has something to do with the detector connections. GM tubes have been around for many decades. It could be it was once easier (and maybe...
- brentkiosk
- Post #2
- Dec 2, 2005
- Forum: Ask a Technical Professional
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is there some physical property that decreases proportional to distance^3

The field due to a dipole drops off as r^3.
- brentkiosk
- Post #6
- Nov 17, 2005
- Forum: Ask a Technical Professional
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Wireless power transmission

An AC carrying inductor placed near the steel plate will induce eddy currents in the plate (because it's a conductor). You will probably end up using quite a bit of your power in just heating up the plate with the eddy currents. As others have said, it really seems as if you should be trying...
- brentkiosk
- Post #13
- Nov 1, 2005
- Forum: Ask a Technical Professional
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Radio Question

Any nonlinear element in a circuit can cause an unintentional detection of a strong radio signal. The speaker wirew, power cord, audio input cables (even if shielded) etc. can serve as an antenna bringing RF into your amp. If this RF voltage is big enough, iit can drive something out of its...
- brentkiosk
- Post #2
- Aug 16, 2005
- Forum: Ask a Technical Professional
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how fast does a space station have to spin to generate gravity?

Well - It's a pretty round number and I didn't have a calculator within reach.
- brentkiosk
- Post #5
- Aug 6, 2005
- Forum: Ask a Technical Professional
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how fast does a space station have to spin to generate gravity?

It depends on the size. The centripetal acceleration is v^2/r at a distance r from the center of rotation. For example, to get 1 g at 100 meters, you would have to go about 30 m/s. That would amount to about 3 rpm!
- brentkiosk
- Post #2
- Aug 6, 2005
- Forum: Ask a Technical Professional
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Sound-upon-sound question

Multiple sources of sound just add. What actually adds is the sound waves, the total wave amplitude at any time and location being the sum of all the waves. Usually, such as with the vacuum cleaner and TV, the sources have no defininite phase relationship, and you can just add the intensities...
- brentkiosk
- Post #2
- Aug 6, 2005
- Forum: Ask a Technical Professional
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200+amps on 12v

This is a lot of power - 2400 watts. Even at 100% efficiency, this translates to 20 A at 120 volts. So, when you get it done, you will need a 30 A circuit to run it. Starting from 240 VAC might be a better option. DC power supplies in this range are possible, but it might cost a few bucks...
- brentkiosk
- Post #4
- Jul 27, 2005
- Forum: Ask a Technical Professional

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