Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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  #11   Report Post  
Old June 11th 05, 12:17 AM
NSM
 
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wrote in message
oups.com...

read the original post - talking about a sine wave bouncing between +5V
and +15V - no where near negative


That's an AC wave with a DC offset.

N




  #13   Report Post  
Old June 11th 05, 12:51 AM
Don Bowey
 
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On 6/10/05 3:13 PM, in article
,
" wrote:

How come? Do you object to the term "DC" - is monophasic acceptable to
you?

See also:

http://64.233.161.104/search?q=cache...com/global/our
_product/sp_Inverter/3_techno.html+%2B%22dc+sine+wave%22&hl=en&lr=lang_ en


Your posts have all the characteristics that indicate you are a troll. If
you aren't I suggest you quit being combative and learn from what the
posters are saying.

And re the link; that refers to an inverter that uses a DC input and outputs
a sinewave. You must be troll.





  #15   Report Post  
Old June 11th 05, 01:09 AM
ehsjr
 
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wrote:
2 questions about a fully DC Sine Wave....let's suppose you have a DC
Sine wave which varies from +5V to +15V peak-to-peak going into a load
with R, L, and C components.....

Question #1:
Is the load's impedance a function of R, L, and C (and wave frequency)
or is it simply just R (i.e. Z=R)? In other words does non-resistive
impedance (L + C) really only matter with an AC signal OR anytime
voltage varies periodically (even if it is all DC)?


Question #2:
Would a "regular" negative peak detector ciruit, like shown he

http://www.elektroda.net/cir/index/D...CTOR.htmgative


work for the DC Wave described? Will it output +5V or do negative peak
detectors only work for AC signals?

Thank you.


Question 1: A capacitor "capacitates" whether it sees
AC or DC. An inductor "inducts" whether it sees AC or
DC. A resistor resists whether it sees AC or DC. You
might find it beneficial to think of what happens to
each component on a component level rather than thinking
of total impedance. Understand what each component
does, and circuit impedance will make more sense.

Question 2: 404 file not found error
That said, you can peak detect on a varying DC
sine. As someone else said, its AC with a DC offset.

Ed


  #16   Report Post  
Old June 11th 05, 01:10 AM
Bob Monsen
 
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wrote:
2 questions about a fully DC Sine Wave....let's suppose you have a DC
Sine wave which varies from +5V to +15V peak-to-peak going into a load
with R, L, and C components.....

Question #1:
Is the load's impedance a function of R, L, and C (and wave frequency)
or is it simply just R (i.e. Z=R)? In other words does non-resistive
impedance (L + C) really only matter with an AC signal OR anytime
voltage varies periodically (even if it is all DC)?


The impedance of a set of passive devices is independent of the voltage
across them. It only depends on R, L, C, and f. The fact that there is a
DC component makes no difference.

An inductor will pass DC current as if it were a wire. Only differences
in current cause a voltage across it. A capacitor will not pass DC, so
the DC does not matter. Obviously, a resistor is a resistor, and cares
nothing for ac vs dc.

This is only true for ideal components. In the real world, inductors,
caps and resistors have voltage limitatations. They are usually well
beyond 15V, though.


Question #2:
Would a "regular" negative peak detector ciruit, like shown he

http://www.elektroda.net/cir/index/D...CTOR.htmgative


work for the DC Wave described? Will it output +5V or do negative peak
detectors only work for AC signals?

Thank you.


Your link has crap on the end. Here it is without the crap:

http://www.elektroda.net/cir/index/D...20DETECTOR.htm

With this circuit, the input at V+ will always be outside the power
rails. Thus, it will not work.

NOTE: I changed the followup-to field to sci.electronics.basics, because
that is where this thread belongs. I hope you don't mind.

---
Regards,
Bob Monsen
  #17   Report Post  
Old June 11th 05, 01:34 AM
Rich Grise
 
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On Fri, 10 Jun 2005 14:55:02 -0700, jackbruce9999 wrote:

2 questions about a fully DC Sine Wave..


If you think that the term "fully DC Sine Wave" even means anything,
then you have not understood the coursework. Either your teacher is
incompetent, or you have been spending too much time partying and not
enough time studying.

Good Luck!
Rich

  #18   Report Post  
Old June 11th 05, 01:37 AM
Rich Grise
 
Posts: n/a
Default

On Fri, 10 Jun 2005 16:51:10 -0700, Don Bowey wrote:

On 6/10/05 3:13 PM, in article
,
" wrote:

How come? Do you object to the term "DC" - is monophasic acceptable to
you?

See also:

http://64.233.161.104/search?q=cache...com/global/our
_product/sp_Inverter/3_techno.html+%2B%22dc+sine+wave%22&hl=en&lr=lang_ en


Your posts have all the characteristics that indicate you are a troll.


Bull****. This kid is not a troll, by any means. He's just a student
desperate to weasel answers to his final without having to learn the
material he was supposed to have learned while partying and chasing tail.

A troll is a much more serious matter. This is just a child who needs
to fail the course, have Mom and Dad scold him, and next semester,
pay attention in class.

Cheers!
Rich

  #19   Report Post  
Old June 11th 05, 02:05 AM
John Popelish
 
Posts: n/a
Default

wrote:
2 questions about a fully DC Sine Wave....let's suppose you have a DC
Sine wave which varies from +5V to +15V peak-to-peak going into a load
with R, L, and C components.....

Question #1:
Is the load's impedance a function of R, L, and C (and wave frequency)
or is it simply just R (i.e. Z=R)? In other words does non-resistive
impedance (L + C) really only matter with an AC signal OR anytime
voltage varies periodically (even if it is all DC)?


Question #2:
Would a "regular" negative peak detector ciruit, like shown he

http://www.elektroda.net/cir/index/D...CTOR.htmgative


work for the DC Wave described? Will it output +5V or do negative peak
detectors only work for AC signals?

Thank you.


According to Fourier analysis, any repeating waveform can be
decomposed into harmonically related and appropriately phase shifted
sine waves and also a DC component. If all the components involved
are linear, then they react to each of these components,
independently, and the result is the linear sum of all those
reactions. So the capacitors react to the DC component as open
circuits, and the inductors as short circuits. At all frequencies,
the resistances follow ohms law, and at each AC harmonic, the
inductances and capacitances react in their normal frequency dependent
ways.

Throw in one nonlinear component, like a diode, and you have to do a
completely different kind of analysis.
  #20   Report Post  
Old June 11th 05, 02:29 AM
Fred Bloggs
 
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Question #2:
Would a "regular" negative peak detector ciruit, like shown he

http://www.elektroda.net/cir/index/D...CTOR.htmgative


work for the DC Wave described?


That is not a "regular" peak detector, it is a comparator used as an
overcompensated opamp follower and exploits the open collector output
characteristic of fast discharge and slow ( 10 second) charge of the
capacitor. In concept it will work for a varying "DC sine wave" by
replacing "-Vcc" with "GND" and all "GND"'s with "+15V" in that circuit
diagram only. Then Vout= "Vpk,neg" =+5V.






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