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a question on power supply, i am new

ArchiverArchiver Posts: 46,084
edited 2003-11-19 17:48 in General Discussion
hi all

i have a question on power supply.
suppose i want to get max output of 24V@3A
and i can only get a parallel 12V@3A(24VCT) transformer
is there anyway that i can get 24V@2A from this transformer?
can i use step-up dc-dc converter to do the job?
if it can be done, how?
or is there any easy way to achieve the goal?
the ouput can vary from 0 to 24V@3A.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-11-18 13:15
    --- In basicstamps@yahoogroups.com, "i_drives" <i_drives@y...> wrote:
    > hi all
    >
    > i have a question on power supply.
    > suppose i want to get max output of 24V@3A
    > and i can only get a parallel 12V@3A(24VCT) transformer
    > is there anyway that i can get 24V@2A from this transformer?
    > can i use step-up dc-dc converter to do the job?
    > if it can be done, how?
    > or is there any easy way to achieve the goal?
    > the ouput can vary from 0 to 24V@3A.

    Probably the easiest way is to get a new transformer.

    Assuming your unit is 6V from center tap to either side, and 12V
    across the coils, you don't have enough current.

    A second transformer in series would offer 24V at 3 amps, or in
    parallel, would offer 12V @ 6amps.

    a DC to DC converter will cost much more than a new transformer but
    will only up the voltage, not the amps. in fact, you will lose the
    amps when you up the voltge.


    Check www.mpja.com or Jameco for transformers.

    Dave
  • ArchiverArchiver Posts: 46,084
    edited 2003-11-18 14:29
    If you wire the two output 12v@3a in series, the uoutput will be 24 v @3a.
    Just tie one end of the one 12 v winding to the other end of the next 12
    volt winding. The two remaining connections will be 24 volts. Measure the
    output voltage and if it is very low instead of 24 volts nominal, just move
    the connection to the other end of one winding and that should fix the
    problem. If the output is truely 24 volts ct, then you need do no jumpers.
    The output is already 24 volts and the center tap will be 12 volts. I hope
    I didn't confuse you more!
    jim
    http://www.geocities.com/jimforkin2003/


    Original Message
    From: i_drives [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=8-Dc3NkZgo9Lwr_9DgFXYqzsbusHcbeSUXkaOCY_DpEmpy5eqTvjvcenrvBaZyT8-3wIYbxydEfNpA]i_drives@y...[/url
    Sent: Tuesday, November 18, 2003 1:25 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] a question on power supply, i am new


    hi all

    i have a question on power supply.
    suppose i want to get max output of 24V@3A
    and i can only get a parallel 12V@3A(24VCT) transformer
    is there anyway that i can get 24V@2A from this transformer?
    can i use step-up dc-dc converter to do the job?
    if it can be done, how?
    or is there any easy way to achieve the goal?
    the ouput can vary from 0 to 24V@3A.


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  • ArchiverArchiver Posts: 46,084
    edited 2003-11-18 18:36
    does that mean that i can not get negative voltage output from
    transformer?
    if so, is there anyway to get negative voltage?

    thanks for you reply




    --- In basicstamps@yahoogroups.com, "Jim Forkin" <jjf@p...> wrote:
    > If you wire the two output 12v@3a in series, the uoutput will be
    24 v @3a.
    > Just tie one end of the one 12 v winding to the other end of the
    next 12
    > volt winding. The two remaining connections will be 24 volts.
    Measure the
    > output voltage and if it is very low instead of 24 volts nominal,
    just move
    > the connection to the other end of one winding and that should fix
    the
    > problem. If the output is truely 24 volts ct, then you need do no
    jumpers.
    > The output is already 24 volts and the center tap will be 12
    volts. I hope
    > I didn't confuse you more!
    > jim
    > http://www.geocities.com/jimforkin2003/
    >
    >
    >
    Original Message
    > From: i_drives [noparse][[/noparse]mailto:i_drives@y...]
    > Sent: Tuesday, November 18, 2003 1:25 AM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] a question on power supply, i am new
    >
    >
    > hi all
    >
    > i have a question on power supply.
    > suppose i want to get max output of 24V@3A
    > and i can only get a parallel 12V@3A(24VCT) transformer
    > is there anyway that i can get 24V@2A from this transformer?
    > can i use step-up dc-dc converter to do the job?
    > if it can be done, how?
    > or is there any easy way to achieve the goal?
    > the ouput can vary from 0 to 24V@3A.
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    Subject and
    > Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2003-11-18 21:48
    --- In basicstamps@yahoogroups.com, "i_drives" <i_drives@y...> wrote:
    > does that mean that i can not get negative voltage output from
    > transformer?
    > if so, is there anyway to get negative voltage?
    >
    > thanks for you reply



    google 'free lunch'

    you wanna get 24V from a 12V transformer, and get 4 amps from a 3 amp
    unit, plus also get a negative voltage?

    The 12V/3A unit delivers 36 watts at 12V
    and only 1.5 amps at 24V.

    with a center tap, you can get +6 and -6 if it is 6-12-6

    Dave
  • ArchiverArchiver Posts: 46,084
    edited 2003-11-19 17:48
    Negative and positive voltages are a concept related to direct current.
    Transformers do not produce direct current. They only produce alternating
    current at the frequency applied to the primary side and at a voltage
    determined by the ratio of the primary to secondary turns. A multi-winding
    transformer can have one winding rectified and filtered to produce a
    negative voltage as related to the other winding(s). This is not to say that
    an ac voltage can not be negative (or positive) to another voltage.

    Hope this clarified the situation a bit.

    jim
    http://www.geocities.com/jimforkin2003/


    Original Message
    From: Dave Mucha [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=K70ED-AUQUmUJ1E1kCXb4qq5tGYRnnjI7rgx8Q5DvFVXVZ0LKSVIx6F8AwG4TdL3we7Mm0zpJ4M]davemucha@j...[/url
    Sent: Tuesday, November 18, 2003 4:48 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: a question on power supply, i am new


    --- In basicstamps@yahoogroups.com, "i_drives" <i_drives@y...> wrote:
    > does that mean that i can not get negative voltage output from
    > transformer?
    > if so, is there anyway to get negative voltage?
    >
    > thanks for you reply



    google 'free lunch'

    you wanna get 24V from a 12V transformer, and get 4 amps from a 3 amp
    unit, plus also get a negative voltage?

    The 12V/3A unit delivers 36 watts at 12V
    and only 1.5 amps at 24V.

    with a center tap, you can get +6 and -6 if it is 6-12-6

    Dave




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