Hi again,
Didnt get any PM, dont know what happened there.
I've used the FTDI chip and it's great, but they only come in the
SM SS packages and i really wanted to get something in a DIP
package so that's why i thought of the PIC chips. They do have
that 18F chip in DIP right?
Also, does the Microchip demo require a C compiler for the PIC?
Yes i wondered about soldering those BGA chips too, if they could
be done with perhaps a heat gun on the back of the pc board.
I havent tried anything yet though and have been using mostly
the DIP packages, except for a few op amp and reference diode
chips and that FTDI chip which was very hard to solder. I was
also looking into some magnification to use for this to help see
what was being soldered.
The AC transfer switch is a solid state relay, which takes two
AC inputs and provides one AC output. When the line is present,
the line is switched to the output (with very high current SCRs).
When the line drops below a certain point the alternate AC input
(usually from a battery powered AC UPS system) is switched to
the output keeping the load alive.
The PC scope used memory chips and fast counters to store the
results from a fast AD converter, then simply uploads to the
computer via a special pc card that fits in a slot. Unfortunately
it was build back when the ISA bus was popular, so it no longer
plugs into the bus (which is now PCI). I had all the boards
made except the ad converter board (which would have been
simple) but then as the technology changed i didnt feel like
making a PCI interface board so i dropped the project. I still
have all the boards though and can restart at some point but
im not so sure i need this anymore as i also purchased a small
analog scope that i use for most stuff these days and although
the bandwidth isnt that great it's ok for now.
A digital scope these days can be made from a fast AD converter,
all you need to do is have a way to store the data that comes
streaming out of the AD converter in real time, then upload
to the PC, perhaps these days by USB would work great.
The 4 channel monitor is basically a voltmeter that connects to the
PC port and allows making voltage measurements using four different
inputs. It's basically like using 4 voltmeters at the same time.
The thing that's different about the software is it not only allows
one to measure voltage, but it was built to also work with batteries
and temperature measurement (something that often goes with
battery charging). The battery applications are charging and
accurate testing of the battery, as to determine it's ability
to hold a charge or how much charge it can hold.
For example, a typical AA NiMH cell is rated for 2500mAh, but
after being charged the monitor is connected and a controlled
discharge is done (using a cheap resistor). The monitor hardware
and software keeps track of the voltage and current of the cell
as it discharges and tallies up the total charge capacity of
the cell and provides a readout that states what the real
capacity of the cell is. I did many cells this way and i found
many 2500 cells to be actually rated at around 1700 or so. The
cells were made by Energizer and it is known to be a problem
with some of them now.
Here's a screen shot:
I use the scientific calculator quite a bit for doing some problems.
The eigens of a matrix are sometimes used to determine the transfer
function in the time domain. We dont really have to do this, but
then again it's just another step that allows another way to do
something. I was thinking perhaps we can start with what is called
the "Transition Matrix" which allows the numerical calculation of a
response without resorting to calculus. It's pretty nice how this
works. Still, i think we should start off with something more
basic to get a feel for the basic properties of things. Once you
get into analyzing systems there comes a sort of detachment from
reality anyway, almost the same as when you try to visualize 12
dimensions in space when usually we use only 3. As the systems
grow in complexity, there is more detachment so there is some
loss of understanding of how a device really works i think. This
means it's good to look at simple stuff too i guess
Since you have some programming experience too then you wont find
it hard to pick up a new language that is easier to use than C.
It's like a subset of C but has two ways to use it:
with the interpreter or translate to C and build using a standard
C compiler. The interpreter is nice because it lets you run
a program immediately to see how it works and to get the results
from your code. For example, here's a for loop that prints the
value of the loop counter to the console:
for k=1 to 10 do
printf(1,"%d\n",k)
end for
You can see how close this is to the C language so it's fast to pick up.
This is a good language to work in because it's fast to create something
new and doesnt have to be compiled either. If you are interested i'll
post a link.
Parallel and Series...
Sorry to ask so many basic questions, but i find that when i work with
people online with various projects i often dont have a grasp of what
background they have and that prevents me from communicating more
effectively with them, so i like to ask a few questions.
As to the 5 resistor circuit, im just wondering where to start and
maybe working with a few resistor networks would get us there quick
and then we can generalize to use capacitors and inductors along
with the resistors and find we will be doing almost the same things
for all of these most important devices. In the mean time it will
help me to refresh too as i havent been doing as much as i used to
do either in the past
Ok, we wont worry about the State equations just yet.
I had to ask about the voltage and current too because i find that
some people dont have a very good understanding of these things.
In the engineering texts they talk about a voltage being a quantity
that is simply 'across' a two terminal element, and a current as
being a quantity that is 'through' an element. Thus one is measured
across and the other through. When converting a circuit to
algebraic it's good to realize that it is really that simple and
then just follow a basic set of rules, while at the same time
getting a feel for how a simple circuit works.
Yes a good example of a nonlinear device is a transistor, so i guess
you have worked with them. To start with though we would work with
linear devices and work from there. There is so much that can be
done with linear circuits that it's a good idea to know about them.
I was wondering if you have ever worked with magnetic materials
like the kinds of materials used for inductors and transformers.
Sometimes you end up designing your own inductor, but then again
there are an awful lot of them on the market today in various
sizes and current ratings so perhaps this is best left alone for
now. I buy my inductors ready made too now rather than wind
my own. The prices are reasonable i guess unless you decide you
want to build 1000 of something, then you might want to design
your own inductor provided you can wind it ok.
I didnt think you would drop out
as you seem to have a
big interest in analog and digital circuits, maybe as much as
i do?
The PIC programmer i have is the most basic one, the PICStart1.
It does a few chips and i have gotten it to work with some it
wasnt made to work with, but not the 18F series. I could always
get a new programmer i guess, but right now i am doing other
things anyway so im not sure if i would have the time to dedicate
to working on this again, at least not right now. Perhaps in
the near future.
Here's a link to the online course:
http://www.candlepowerforums.com/vb/sho ... University
You'll want to skip through the very basic stuff, and i think
we would be better off using a programming language like
i mentioned rather than the HP calculator because that can be
somewhat hard to use...maybe that's why everyone gave up.
