voltage regulator +/-

Discussion in 'General Science & Technology' started by cato, Jan 4, 2006.

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  1. MetaKron Registered Senior Member

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    Sorry, don't know anything about SPICE. Is there a freeware program that I can download?
     
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  3. cato less hate, more science Registered Senior Member

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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:
    http://www.electronics-lab.com/downloads/schematic/013/
    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.
     
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  5. leopold Valued Senior Member

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    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
     
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  7. leopold Valued Senior Member

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    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
     
  8. leopold Valued Senior Member

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    17,455
    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
     
  9. cato less hate, more science Registered Senior Member

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    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.
     
  10. leopold Valued Senior Member

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    17,455
    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
     
  11. cato less hate, more science Registered Senior Member

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    2,959
    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 =].
     
  12. leopold Valued Senior Member

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    17,455
    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
     
  13. cato less hate, more science Registered Senior Member

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    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 =].
     
  14. leopold Valued Senior Member

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    redraw it in pspice?
     
  15. cato less hate, more science Registered Senior Member

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    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.
     
  16. leopold Valued Senior Member

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    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 . . .
     
  17. cato less hate, more science Registered Senior Member

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  18. leopold Valued Senior Member

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    i read the thread but didn't find anything interesting
     
  19. leopold Valued Senior Member

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    cato
    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
     
  20. cato less hate, more science Registered Senior Member

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  21. leopold Valued Senior Member

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    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.
     
  22. cato less hate, more science Registered Senior Member

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  23. leopold Valued Senior Member

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    okay, i clicked on schematic and nothing happens
    so i guess i have to reinstall it right?
     
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