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PWM Amplification to 0-10V — Parallax Forums

PWM Amplification to 0-10V

ArchiverArchiver Posts: 46,084
edited 2004-01-24 16:31 in General Discussion
Hi All,

Am fairly new to electronics so bear with me if this sounds daft! I
need to amplify the O-5V PWM signal that the stamp outputs to a 0-
10V PWM signal. Has anyone any information on how to go about this.
Any help will be most greatfully appreciated.
Many thanks

Hugh

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 14:53
    There was a pretty lengthy post about this at
    http://groups.yahoo.com/group/basicstamps/message/39364.

    In his case, he needed 0-12V and 4W so you actually have it easier. You
    could select an op amp to run at 12V and easily get 10V out.

    Regards,

    Al Williams
    AWC
    Stamp FAQ: http://www.wd5gnr.com/stampfaq.htm


    Original Message
    From: hughgoodbody [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=-K5cwdxQbKmvqxmDZ7T42VNykHXNswHgfEEO5jgn3K8-ls_PE_NLhZfz1GPPVQS496pZTQ9ovVetgSRz5eEZBwM]hughgoodbody@y...[/url
    Sent: Wednesday, January 21, 2004 8:48 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] PWM Amplification to 0-10V


    Hi All,

    Am fairly new to electronics so bear with me if this sounds daft! I
    need to amplify the O-5V PWM signal that the stamp outputs to a 0- 10V PWM
    signal. Has anyone any information on how to go about this.
    Any help will be most greatfully appreciated.
    Many thanks

    Hugh


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  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 15:20
    Simple, use a 15v supply through a resistor to Vin (NOT Vdd) and a 470uf cap
    from Vin to Vss to power the stamp. The resistor value
    should be selected to limit the voltage to the stamp, 75 ohms will drop 7.5v at
    100ma and leave 7.5v to power the stamp, if your app
    draws a lot less than the max (most of mine are around 20ma.) try 100 to 470
    ohms the goal here is to keep the stamp input voltage
    between 5.5v an 11v to limit its internal dissipation.

    Now finally use the full 15v to power an op amp such as the lm2902 that is
    capable of output swings to 0v, and feed your pwm signal
    to its non-inverting input, take your output directly from its output pin and
    connect a resistor from there to the inverting input,
    add another equal value resistor from the inverting input to Gnd. The inverting
    input will now see 1/2 the op-amps output and drive
    it's output to 2x the input voltage.
    KF4HAZ - Lonnie
    From: "hughgoodbody" <hughgoodbody@y
    > Hi All,
    >
    > Am fairly new to electronics so bear with me if this sounds daft! I
    > need to amplify the O-5V PWM signal that the stamp outputs to a 0-
    > 10V PWM signal. Has anyone any information on how to go about this.
    > Any help will be most greatfully appreciated.
    > Many thanks
    >
    > Hugh
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 15:31
    use a simple inverting op amp with a gain of 2 and 0-5 becomes 0-10. Buffer
    the output with an inverting unity (no gain) stage and there you are. A
    dual-op amp like an MC1458 would probably work well for you.

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


    Original Message
    From: hughgoodbody [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=8UAdY2ruVlG9VQ_UTv1SG-cinv8pLzcXXXAft-Qa6wOBe-9V4OfteL_dGJ7QRPfEGUUNLu8AmeBaPu-IQCjG7Mg]hughgoodbody@y...[/url
    Sent: Wednesday, January 21, 2004 9:48 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] PWM Amplification to 0-10V


    Hi All,

    Am fairly new to electronics so bear with me if this sounds daft! I
    need to amplify the O-5V PWM signal that the stamp outputs to a 0-
    10V PWM signal. Has anyone any information on how to go about this.
    Any help will be most greatfully appreciated.
    Many thanks

    Hugh


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
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    Body of the message will be ignored.


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  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 16:13
    Hugh,

    Two questions:

    1) how much current can the 0 to 5 volt PWM signal sink/source?

    2) how much current does teh 0 to 10 volt PWM signal need to sink or source?

    Setting up this circuit should be very simple once I know answers to the
    above.

    Ken

    In a message dated 1/21/2004 7:07:06 AM Pacific Standard Time,
    hughgoodbody@y... writes:
    Hi All,

    Am fairly new to electronics so bear with me if this sounds daft! I
    need to amplify the O-5V PWM signal that the stamp outputs to a 0-
    10V PWM signal. Has anyone any information on how to go about this.
    Any help will be most greatfully appreciated.
    Many thanks

    Hugh


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 17:47
    Ken,

    The 0-5V PWM Signal I think will be approx 5-10mA

    The 0-10V PWM Signal Max Current is 1.1A and max Power is 0.5W

    Hope this helps!


    --- In basicstamps@yahoogroups.com, smartdim@a... wrote:
    > Hugh,
    >
    > Two questions:
    >
    > 1) how much current can the 0 to 5 volt PWM signal sink/source?
    >
    > 2) how much current does teh 0 to 10 volt PWM signal need to sink
    or source?
    >
    > Setting up this circuit should be very simple once I know answers
    to the
    > above.
    >
    > Ken
    >
    >
    > In a message dated 1/21/2004 7:07:06 AM Pacific Standard Time,
    > hughgoodbody@y... writes:
    > Hi All,
    >
    > Am fairly new to electronics so bear with me if this sounds daft!
    I
    > need to amplify the O-5V PWM signal that the stamp outputs to a 0-
    > 10V PWM signal. Has anyone any information on how to go about
    this.
    > Any help will be most greatfully appreciated.
    > Many thanks
    >
    > Hugh
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-22 00:37
    It helps!!!

    Couple other questions I forgot to ask, what is the frequency of the PWM
    signal.

    Also, will the 0 to 10 v pwm provide power (source current) to the load, or
    provide ground (sink current) to the load.

    Ken

    In a message dated 1/21/2004 1:19:17 PM Pacific Standard Time,
    hughgoodbody@y... writes:
    Ken,

    The 0-5V PWM Signal I think will be approx 5-10mA

    The 0-10V PWM Signal Max Current is 1.1A and max Power is 0.5W

    Hope this helps!


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-22 10:01
    Ken,

    The signal will provide current to the load. As to the frequency, i
    am not sure. The signal is being generated from the stamp and the
    cycle value am using is 100ms, but this can be altered.


    --- In basicstamps@yahoogroups.com, smartdim@a... wrote:
    > It helps!!!
    >
    > Couple other questions I forgot to ask, what is the frequency of
    the PWM
    > signal.
    >
    > Also, will the 0 to 10 v pwm provide power (source current) to the
    load, or
    > provide ground (sink current) to the load.
    >
    > Ken
    >
    >
    > In a message dated 1/21/2004 1:19:17 PM Pacific Standard Time,
    > hughgoodbody@y... writes:
    > Ken,
    >
    > The 0-5V PWM Signal I think will be approx 5-10mA
    >
    > The 0-10V PWM Signal Max Current is 1.1A and max Power is 0.5W
    >
    > Hope this helps!
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-24 16:31
    Hello,

    I'm not 100% sure what the signal is supposed to look
    like at the load, but here's a couple ideas:

    1) Filter the PWM signal from the Stamp through an R/C
    circuit, then drive the varying signal into a power
    op-amp (something like a TDA2040 or LM1875, etc. with
    appropriate power supply and heatsinking). The power
    op-amp can provide the necessary gain to get get the
    signal amplitude you're looking for and can easily
    drive +/- a couple amps. These are designed for audio,
    so they can easily handle from DC to the fastest
    signal a Stamp can deliver.

    2) Drive the PWM signal directly into a power switch
    (like a TC4425 or UC2710 from Digi-Key also with
    appropriate power supply). These switches will both
    sink and source from 3 to 6 amps with very fast
    slew-rates. Plus, these have both an inverting and
    non-inverting output so you can run them in a bridged
    configuation to double the output swing to the load.
    Best of all is these saturate so well, the don't
    require heatsinking and are in an 8-pin DIP package.
    This will provide a high-current PWM signal to the
    load, but the voltage delivered will depend on the
    power supply rails or bridge configuration. With the
    bridge configuration, you only need a single 5V supply
    to get 0-10 volts.

    Regards,
    DrDiode

    --- hughgoodbody <hughgoodbody@y...> wrote:
    > Ken,
    >
    > The signal will provide current to the load. As to
    > the frequency, i
    > am not sure. The signal is being generated from the
    > stamp and the
    > cycle value am using is 100ms, but this can be
    > altered.
    >
    >
    > --- In basicstamps@yahoogroups.com, smartdim@a...
    > wrote:
    > > It helps!!!
    > >
    > > Couple other questions I forgot to ask, what is
    > the frequency of
    > the PWM
    > > signal.
    > >
    > > Also, will the 0 to 10 v pwm provide power (source
    > current) to the
    > load, or
    > > provide ground (sink current) to the load.
    > >
    > > Ken
    > >
    > >
    > > In a message dated 1/21/2004 1:19:17 PM Pacific
    > Standard Time,
    > > hughgoodbody@y... writes:
    > > Ken,
    > >
    > > The 0-5V PWM Signal I think will be approx 5-10mA
    > >
    > > The 0-10V PWM Signal Max Current is 1.1A and max
    > Power is 0.5W
    > >
    > > Hope this helps!
    > >
    > >
    > > [noparse][[/noparse]Non-text portions of this message have been
    > removed]
    >
    >
    > 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.
    >
    >
    > Yahoo! Groups Links
    >
    > To visit your group on the web, go to:
    > http://groups.yahoo.com/group/basicstamps/
    >
    > To unsubscribe from this group, send an email to:
    > basicstamps-unsubscribe@yahoogroups.com
    >
    > Your use of Yahoo! Groups is subject to:
    > http://docs.yahoo.com/info/terms/
    >
    >


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