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Transformer

ArchiverArchiver Posts: 46,084
edited 2001-05-05 14:16 in General Discussion
Hi all,

Dose any one know where I might find a step-up Transformer. I nead it
to take a 12V input and have around a 30V output. I am going to use a
PWM to control the output. Please Help

Thanks,
TC

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-04-28 18:47
    >Hi all,
    >
    >Dose any one know where I might find a step-up Transformer. I nead it
    >to take a 12V input and have around a 30V output. I am going to use a
    >PWM to control the output. Please Help
    >
    >Thanks,
    >TC
    >

    I also have a need for a voltage transformer to take a 75 kHz 5V pulse
    train up to about 200V at very little current. Any suggestions? Thanks a lot!

    Steve
    Steve Roberts: sroberts@s...
  • ArchiverArchiver Posts: 46,084
    edited 2001-04-30 12:24
    If you don't need too much current, wind one.

    Transformers are97%efficient, so if youhave 12 V and need 30, a 3:1
    ratio will render 36V (approx) so just put a few less turns for 30 V.

    What are you wanting to drive with the 30V?

    Doug


    > To: basicstamps@yahoogroups.com
    > From: Stephen Roberts <sroberts@s...>
    > Date: Sat, 28 Apr 2001 10:47:42 -0700
    > Reply-to: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] Re: Transformer

    > >Hi all,
    > >
    > >Dose any one know where I might find a step-up Transformer. I nead it
    > >to take a 12V input and have around a 30V output. I am going to use a
    > >PWM to control the output. Please Help
    > >
    > >Thanks,
    > >TC
    > >
    >
    > I also have a need for a voltage transformer to take a 75 kHz 5V pulse
    > train up to about 200V at very little current. Any suggestions? Thanks a lot!
    >
    > Steve
    >
    >
    > Steve Roberts: sroberts@s...
    >
    >
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-01 01:45
    At 10:47 AM 4/28/2001 , you wrote:

    >I also have a need for a voltage transformer to take a 75 kHz 5V pulse
    >train up to about 200V at very little current. Any suggestions? Thanks a lot!
    >
    >Steve


    Steve,

    At that frequency regular AC transformers used for
    power supplies won't work, even audio transformers
    are out of range. Most transformer laminations
    are silicon steel and limited to low frequency pulses,
    they just cant magnetize and demagnetize as fast
    as you need.

    A ferrite torrid core will work. There are many different
    types of ferrite materials according to the frequency.
    You'll have to select one for 75khz range, or one that
    can magnetize and demagnetize at 75 KHz without
    saturation of the core, the point where its no longer
    a changing magnetic field.

    Simply wind the core with the appropriate turns ratio
    which looks like 40 to 1. You have to supply enough
    primary turns to keep the core just below the saturation
    point. The secondary turns is 40 times the primary
    turns.You may need to use a resistor on the 5 volt or
    primary side, depending on its DC resistance, or you
    run the risk of shorting out your input driver element,
    gate or transistor when it turns on.

    Better yet, just buy a pulse transformer and miss all
    the fun of winding torrid cores! IT AIN'T EASY!!

    Good Luck,
    Greg
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-02 17:45
    >Better yet, just buy a pulse transformer and miss all
    >the fun of winding torrid cores! IT AIN'T EASY!!

    There's no rule that says you have to use a toroid core for jobs like this.
    EE or EI cores with fitted bobbins make the job much easier. By the way,
    salvaged cores from TV horizontal output transformers should work well at
    75KHz. They normally operate at the 5th harmonic of the H scan rate
    (~15KHz)...

    Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
    Manufacturer of the famous BOB-II Serial Video Text Display Module!
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-04 00:42
    At 09:45 AM 5/2/2001 , you wrote:
    > >Better yet, just buy a pulse transformer and miss all
    > >the fun of winding torrid cores! IT AIN'T EASY!!
    >
    >There's no rule that says you have to use a toroid core for jobs like this.
    >EE or EI cores with fitted bobbins make the job much easier. By the way,
    >salvaged cores from TV horizontal output transformers should work well at
    >75KHz. They normally operate at the 5th harmonic of the H scan rate
    >(~15KHz)...

    You're absolutely right. I was also thinking that a small transformer from
    a 5 volt 1 amp switching power supply may work in reverse too.

    Greg
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-05 14:16
    I assume you are talking about AC and not DC...

    On Sat, 28 Apr 2001 01:24:54 -0000 aconti@n... writes:
    > Hi all,
    >
    > Dose any one know where I might find a step-up Transformer. I nead
    > it
    > to take a 12V input and have around a 30V output. I am going to use
    > a
    > PWM to control the output. Please Help
    >
    > Thanks,
    > TC
    >
    >
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
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