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High Frequency Component in Square Wave questions

I've got other idea. I'll get meters of high gauge wires and measure

3 ohms and use it as resistor. How do I calculate how much will it heat up? I've got Resnick and Holliday 800 page book on Electromagnetisms and still slowly going thru it but need the information asap. Thanks.

Say. Is there a difference in performance if I have say a 20 meter thin cooper wire measuring 3 ohms versus a thick 5 meter cooper wire measuring 3 ohms also?

Thanks. It explains why I fried my power transistors 2 times already. Well if I never go below 60 Hz but go higher to 10Khz. Would it also fry the circuit?? I notice a high pitch sound in the circuit when the frequency is increased linearly from 60 hz to 10 Khz.

Some kind of non-linear detection system that is based on the quantum potentials of the vectors. I can't explain it. I'll ask.

emma

Reply to
emma
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Go read that book. Thicker wire == less resistance pr m cable, since there's far more copper to conduct the current. Think of it as water. Bigger pipe equals lower resistance equals more water. Higher pressure equals more water trough the same pipe.

--
MVH,
Vidar

www.bitsex.net
Reply to
Vidar Løkken

On a sunny day (30 Jun 2005 13:17:39 -0700) it happened "emma" wrote in :

That depends on a lot of factors, for example when you wind it like a coil it will heat up a lot more then when you leave it laying about.

Try it! There is special resistance wire, that you can use to make your own resistance. Google:

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Then you can use shorter length.

Well, since you want to measure magnetic fields, I would use a light bulb, because that wire (especially when the 20 meter is wound) will be a coil of its own, with its own magnetic field, interfering with your setup! I presume you meant 20 meter thick versus 5 meter thin.

At higher [switching] frequencies the switch time of the transistors becomes important (they will dissipate heat while not 100% on or off), and also the losses in the core of the transform will increase. Then there is 'skin effect' in the wire (electricity only flows in outside). For this reason above say 3 kHz you will often see ferroxcube (ferrite) cores. And possibly litze wire (wire made up of many strands).

Squid! Well that should be sensitive enough :-) But what about the liquid cooling and the totally magnetically screened room? Well ask anyways :-)

Reply to
Jan Panteltje

You fellows are being trolled big-time. Can't you see it?

--
St. John
Reply to
St. John Smythe

Perhaps.

Do you know much about low temperature electronics? I am looking at an ADC chip, which has a temperature range of -30 to 80 C. Why wouldn't the chip work with say -50 C? I would like to work with low fields and eliminate as much thermal noise as possible. Any ideas?

Reply to
curiousjohn4

er.

Thanks for this crucial information. I know thicker tungsten means lesser resistance because there are more spaces in the lattice where the electrons can move or vibrate. So it is also valid in pure wires. You save me the trouble of getting very thick wires and more length required because of lower resistance. So I'll just get thinner wire.=20 =20

emma

Reply to
emma

Many thanks for this important information. I'll attempt to build my fried circuit for the third time and just use frequency of 60 hz and above (to 20Khz). I hope it won't fry anymore.

So many thanks for all the information. I have enough to carry on and read the Resnick book with perspective.

emma

Reply to
emma

You thought that way because I asked too many questions. Well. I have gotten the necessary and important information already so I'll carry on myself with the help of Resnick thick book on electromagnetism and not ask too many questions (that is starting to irritate some folks).

Sorry and many thanks.

emma

Reply to
emma

Clearly matches one model but has been amateurish in execution when compared to the other trolls who are regulars here.

Resnick is too advanced for you.

Nice, this, but futile. It is clear you didn't actually understand any of the answers.

Reply to
Strange Indeed

Semantics. Write the equation.

No. Simple addition doesn't cut it. In a series LC circuit, voltages are added in quadrature. The voltages across L and C (+ R_load) aren't in phase.

No. R_ series = 0, R__parallel = infinite. Give the equation. All of the power goes into the resistive load. None elsewhere.

Exactly. Energy and power are conserved.

Professional ? Fields displays delusions of competence.

[[Old Man]
Reply to
Old Man 

--
What equation?  There's RMS current and RMS voltage, and power is just
the product of current and voltage.

>> 2. Since, for a square wave, RMS and peak voltage are the same and
>>   since for a sine wave they're not, a lowpass filtered 120V 60Hz
>>   square wave will yield a 120V _peak_ 60Hz sine wave.  That's about
>>   an 85VRMS sine wave.
>
>No.  Simple addition doesn't cut it.  In a series LC circuit,
>voltages are added in quadrature.  The voltages across L
>and C (+ R_load)  aren't in phase.
Reply to
John Fields

On a sunny day (Mon, 04 Jul 2005 11:53:08 -0500) it happened John Fields wrote in :

John, this is a bit dangerous if that thing really has low output impedance. It will cause the switcher to current limit or blow up...

Enter it in spice, with square wave input, look at current in C. It is set by the Ri of the source (and Rs cap).

in --L------- out | C RL | ---------- is a bit safer I think, but without load can give very high voltages in resonance.

Reply to
Jan Panteltje 

--
I was just thinking of a way to get a lowpass circuit down for Old
man, but you're right.  I didn't even think of that.  Thanks! :-)
Reply to
John Fields

Only for a resistor wherein current and voltage are in phase. The voltage across C / L leads / lags the current by pi / 2. Here's the equation that Fields should have written

Power = V * I * cos( phase)

for L or C phase = + pi / 2 or - pi / 2. In both cases, Power = 0. Write the equation. Go figure.

No way. Cockeyed low pass filter. The capacitor is in parallel with the load, not in parallel with the source. It is then a series LC circuit with the load in parallel with the capacitor.

The capacitor in fields cockeyed circuit dissipates no power. Neither does the inductor.

Resonant circuit is Fields straw man.

Bullshit. Write the equation. "shunted to ground" is magic. "ground" isn't a physical entity. The current flows back to the source, pi / 2 out of phase with the source voltage. There is no net power consumption. Go figure.

[Old Man]\

Reply to
Old Man

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