Discussion in 'General Science & Technology' started by cato, Jan 4, 2006.
Sorry, don't know anything about SPICE. Is there a freeware program that I can download?
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yeah, its called PSpice, I didn't know about it until a school started back up. hence the tinycad drawings.
there is a freeware version here:
make sure you install the "schematic". for some reason it gives you the option not to, but that is where you draw the circuits. odd.
the wipers of the pots connect to op amps.
the input of an op amp require almost zero current
the major problem with pots is passing too much
current at the end of their travel so i don't see any problems
i just got back from the link
the program without the help files is 28 megabytes
i currently have dail-up
i expect to get wireless broadband within the next day or two
but like i said in my previous post
the op amps input require almost zero current
so the pots should be okay
as you decrease the resistance of the pots
the current stays the same
thats why you would have problems
i am not sure about the input current of the op amps you are using
but a 714 require microamps of input
small enough to not worry about
i intend to download the program
and i'll simulate the schematic if you wish
but i expect no problems with the design
metakron and i came up with
the only problem i see is when you have the supply set at half voltage
with adequate heatsinking even that will not be a problem.
a transister will generate more heat when half on
than at saturation. strange but true
I think it will work, I was just wondering if it was possible to simulate it "live" so I could adjust the pot and see what range of voltages I get. I will probably have to alter the circuit each time I want a different pot setting.
thats the whole idea of using a pot to begin with
so you can adjust the voltage by turning a knob
instead of replacing components
to be honest the circuit should work like you want
the only problem would be the current draw on the output transisters
if you draw excessive current at half voltage the transisters will overheat
you can parallel the transisters and heatsink them
you can also fuse the output for protection
i am getting broadband as we speak so i'll download the program
and run some simulations for you
you never did mention how much current you plan on drawing from your supply
I was talking about during simulation. I am not sure there is a way to adjust the pot dynamically in PSpice and get voltage readings the whole time. I have not tried to model my circuit in it yet, so I don't really know.
I am not really sure what kind of current I plan to be drawing =].
i downloaded and installed the pspice program
i saved the most recent schematic you posted to my desktop
how do i get the schematic into the program
pspice won't let me open a png file
you will have to redraw it. the one I posted was made in tiny cad. thats why I have not done it yet, I am busy with homework =].
redraw it in pspice?
yeah, its not that hard. just go to draw-get new part. if you don't do it, i should be able to get it done this weekend.
i just got broadband
took 3 minutes 45 seconds to download a 28 megabyte file
needless to say i'll be scouring the web for some goodies for awhile
since this is your project . . .
good luck with your scouring =]
there is a thread around here somewhere that talks about new things to do after upgrading to broadband.
i read the thread but didn't find anything interesting
i have tried to use the pspice program but i can't figure out how to draw a schematic
the setup program installed several links on my start menu but i don't know which one to use
it should look like this:
if you don't have the "schematics" part, you need to reopen the install file and make sure you select it to install. for some reason it does not install by default.
which link on the start menu do i use to draw the schematic?
i got all the links you show but i don't know which one to use.
the one that says "schematics" =]
okay, i clicked on schematic and nothing happens
so i guess i have to reinstall it right?
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