Jan said:
I am still a bit puzzled to what you are trying to do.
Here are my questions:
If you say 'magnetic field' what field are you referring to,
the one from the coil? So then you have a probe, and measure everywhere
near and in the coil the magnetic field, and plot that?
I am sure there are examples of solenoid (single layer coils) with field
lines on the net, search via google:
solenoid field lines
I find many many hits,
here
http://www.bfafairfax.com/~pfeiffer/concphys/EandM/magnetism.html
The field will be symmetrical if you coil is, so 3D = 2D
Well. Let's just say that I need to know all the magnetic field
configurations of all kinds of signals... square waves with high
freq components, triangular waves, sine waves because I want to
build a radio or other circuit powered by induction (without
contact). For example, a radio put near a computer monitor that
can power itself (by induction).
Do you think all oscilloscopes can show even the high frequency
components in the square waves. Do all have the same sensitivity.
What particular feature must I look for in oscilloscopes? Single
or dual trace, etc?
amplifier --- 3 Ohm -- 1 Ohm coil -- ground
Yes I know this configuration.
Resistors behave the same for AC and DC (except from very high frequencies,
many MHz, where they act like an inductor depending upon their construction).
Won't a 1 Watt 2 ohm resistor explode if I use it in conjunction with
a 2 ohm coil in series. I can't predict the voltage produced by the
power amp since the manufacturers are accurate on the power rating.
Suppose a buy a 100 watt power amp... connect the 4 ohm resistor
and coil at the output.. put the function gen at the input...
initiate a 200 hz sine or square wave signal... what if the voltage
produced is say 50 volts and the current is more than the load can
handle... unless the 4 ohm load would only draw the current it needs
irregardless of the voltage. Is this what you mean. But I need high
current to cause high magnetic field in the coil so I can measure
it easily and representative of computer monitor magnetic field
strength (at the sides).
I designed my own.
Now I use an FPGA (programmable gate array) with a fast DA converter.
You calculate the waveform for say 1024 points, upload to the (very
fast) FPGA internal RAM, and then program the FPGA so it outputs at the
right speed.
I don't want to design my own. There are so many power amps there. I'm
bad in soldering and often produced cold soldering points causing
endless hours of debugging.
Or just program the required pulse sequence (in Verilog).
You are limited by the clock speed divided by the number of samples you want.
64 samples per period at 10MHz output would require a 640 MHz clock!
Mine does not go that fast (and and neither the DA).
And 64 samples is not exactly a 'pure' sine wave.
If you just want the sine waves, use any LC signal RF generator.
If you want only frequencies in the audio range, use the PC sound card,
and a good sound editor.
Hmm... yes.. a good idea.. Pc sound card... it can also produce
current that can cause magnetic field in the coil, right?? What's
the typical amperage of the pc sound card, I need very high
amperage so I can easily measure the magnetic field and typical
of monitor magnetic field strength.
I would call a 10MHz power amp a power amplifier with 10MHz bandwidth....
Oh no... if power amp has bandwidth of 10-20 khz. Then I can't
use higher signals in the function gen above 20 khz??
I tried building a power inverter with variable frequency. It's
designed for 60 hz but I replace some parts so I can use frequency
as low as 1 hz to as high as 10 khz. But after some use, my transistors
always gets fried and have to replace them. Know the reason why?
I think the perfect setup for me is to get a variable frequency
sine wave power inverter. Know any commercially available ones
where you can adjust the frequency?? I don't want to construct
one from kits as so many parts need to be soldered and I always
get cold solders.
emma
