Hi
If a company has a short term outlook for profit, like now
demanded by the stock market it will focus its effors on
the next three months. That makes it likely that people who
are optimist in nature (assume it can be done until proven
otherwise) will get the favor in management. Despite...
Skip:
The PC sound card must have some kind of filter before
digitizing but as IRstuff says I would test it. Do you
have a sine wave generator?
If so set an appropriate level and feed into sound input
and tune the generator up and down the band while looking
at the FFT output. If you can find...
Hi
Every data line should be twisted with its own ground line.
At 200 MB/sec may have to go to coax for each line.
Buy "High Speed Digital Design a Handbook of Black Magic"
by Howard Johnson.
The book is worth every penny even if you don't do high speed design.
Rodar
On Semiconductor make a chip part # NCP1200 that
incorporates a fixed frequency switch mode supply that
can easily do current control. Just use an inductor in
series with your LED and a fast recovery diode around both
LED and inductor. I have used this chip to make a direct
line powered LED...
Hi Skip
I believe most FFT analysers use this oversampling method
to create an anti aliasing filter. The reason is that as
you adjust your instrument to different sampling times
it would call for different AAF cut off.
What is done is incorporate an high frequency analog AAF
that protects the...
Hi
In AC machinery (Transformers and Motors) the resistance
of the copper windings are very low. The inductance of the
windings contribute the majority of the impedance to current flow through the coil. So when no load is applied
and neglecting losses, the self inductance limits the current...
bobm2
Typically a lab has a number of different antennas each
one calibrated for a range of frequencies. Your largest
trouble will be isolating the motor EMI from other sources
of EMI. Labs will place the motor in a chamber that eliminates outside RF and has walls that do not reflect
the RF...
Hello
It sounds like the engine speed is being modulated at
60 and 90 hz. One thing to check is the photocell speed
sensor. Is is retroreflective type. In other words is there
any difference in the pulse start and stop time based on
the position on the fan as it passes. I am thinking of a
fan...
Investigate the construction of a "Faraday Generator"
Just a conducting disk with magnets on each side.
Its true the torque required to pedal will not be linear
with speed. But it seems to me this would be a good thing.
As you pedel faster it gets progressively harder to pedal.
If you...
Jackson1
I think you have the answear there. Capacitive coupling
between the device under test and a grounded metal test
table could cause the unbalenced current in the GFI.
Particularly if switched on when the sine was at the peak.
Or is there internal to the control a static bleed off...
HI
To me the primary factor is how much percent change in
capacitance happens for a movement of 0.1mm. If there is
say 10% capacitance change it is dooable.
By the way motorola just came out with a new chip for
doing e-field capacitive sensor type stuff.
Search online for E field , motorola...
Hi
To understand it helps to consider the load as unchangeable
by the generator. In other words the grid voltage and
frequency cannot be alterted. This is true because of the size of the power grid. As the mechanical power is increased the generator rotor phase angle relative to the
phase angle...
This all begins with the fact that resistive loss in
any conductor is proportional to the square of either
measured value current through or voltage across.
P=I*I*R or P=(V*V)/R
RMS allows to account for the expected heating to be a
non-linear function of the current or voltage.
So which wire...
I think a company called Intusoft makes software like this.
I have not used the magnetic designer but do use their spice package and it performs well.
rodar
Many power supply sections of equipment don't like
that kind of treatment. They get confused as to
whether in shut down mode or startup if the power is
blinking. Ideally the power supply should shut down
and not try to restart until a time delay and make sure
it is in a stable condition. But...
If you do not need hair splitting accuracy
try a RC filter with a cutoff of 5 hz. This
will give a phase shift of around 85 deg.
Then feed this to a AC coupled comparator to
recover the full strengh phase shifted signal.
Otherwise nbucska has a good solution.
Generate a 120 Hz squarewave...
To me there is no difference.
Cheaper meters measure only average values which
are not accurate if the signal differs from a
SIN wave.
If a meter measures RMS it gives the effective power
of the signal accurately.
Beware, all RMS meters have limitations on their measurement ability...
